diff --git a/.github/workflows/rubyonrails.yml b/.github/workflows/rubyonrails.yml
new file mode 100644
index 000000000..30342b153
--- /dev/null
+++ b/.github/workflows/rubyonrails.yml
@@ -0,0 +1,122 @@
+# This workflow uses actions that are not certified by GitHub.  They are
+# provided by a third-party and are governed by separate terms of service,
+# privacy policy, and support documentation.
+#
+# This workflow will install a prebuilt Ruby version, install dependencies, and
+# run tests and linters.
+name: CI/CD
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    
+    env:
+      DATABASE_URL: mysql2://root:expertiza@127.0.0.1:3306/expertiza_test
+      RAILS_ENV: test
+      
+    services:
+      mysql:
+        image: mysql:8.0
+        env:
+          MYSQL_ROOT_PASSWORD: expertiza
+          MYSQL_DATABASE: expertiza_test
+        ports:
+          - 3306:3306
+        options: --health-cmd="mysqladmin ping" --health-interval=10s --health-timeout=5s --health-retries=3
+
+    steps:
+      - uses: actions/checkout@v3
+      
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: 3.2.7
+          bundler-cache: true
+          
+      - name: Setup Node.js
+        uses: actions/setup-node@v3
+        with:
+          node-version: '18.x'
+          
+      - name: Install system dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y netcat-traditional
+          
+      - name: Install Ruby dependencies
+        run: |
+          gem update --system
+          gem install bundler:2.4.7
+          bundle install
+          
+      - name: Setup database
+        run: |
+          bundle exec rails db:create RAILS_ENV=test
+          bundle exec rails db:schema:load RAILS_ENV=test
+          
+      - name: Set up code climate test-reporter
+        run: |
+          curl -L https://codeclimate.com/downloads/test-reporter/test-reporter-latest-linux-amd64 > ./cc-test-reporter
+          chmod +x ./cc-test-reporter
+          ./cc-test-reporter before-build
+
+      - name: Run model tests
+        run: bundle exec rspec spec/models
+
+      - name: Run controller tests
+        run: bundle exec rspec spec/requests/
+
+      - name: Format code coverage report
+        run: ./cc-test-reporter format-coverage -t simplecov -o "coverage/codeclimate.models.json" --debug
+
+      - name: Upload coverage artifacts
+        uses: actions/upload-artifact@v4
+        with:
+          name: code-coverage-artifacts
+          path: coverage/
+
+
+  publish_code_coverage:
+    needs: test  # Ensures this job runs after the test job
+    runs-on: ubuntu-latest
+    if: github.event_name == 'push' && github.ref == 'refs/heads/main'  # Only run when there's a push to main branch
+
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/download-artifact@v4
+        with:
+          name: code-coverage-artifacts
+          path: coverage/
+
+      - name: Upload code-coverage report to code-climate
+        run: |
+          export GIT_BRANCH="${GITHUB_REF/refs\/heads\//}"
+          curl -L https://codeclimate.com/downloads/test-reporter/test-reporter-latest-linux-amd64 > ./cc-test-reporter
+          chmod +x ./cc-test-reporter
+          ./cc-test-reporter sum-coverage coverage/codeclimate.*.json 
+          ./cc-test-reporter after-build -t simplecov -r ${{ secrets.CC_TEST_REPORTER_ID }}
+
+  docker:
+    needs: test
+    if: github.ref == 'refs/heads/main'
+    runs-on: ubuntu-latest
+    
+    steps:
+      - uses: actions/checkout@v3
+      
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+        
+      - name: Build Docker image
+        uses: docker/build-push-action@v4
+        with:
+          context: .
+          push: false
+          tags: expertiza-backend:latest
+
diff --git a/app/controllers/api/v1/account_requests_controller.rb b/app/controllers/api/v1/account_requests_controller.rb
index 30cb17fa7..3a40eea7c 100644
--- a/app/controllers/api/v1/account_requests_controller.rb
+++ b/app/controllers/api/v1/account_requests_controller.rb
@@ -18,7 +18,7 @@ def create
     if @account_request.save
       response = { account_request: @account_request }
       if User.find_by(email: @account_request.email)
-        response[:warnings] = 'WARNING: User with this email already exists!'
+        response[:warnings] = I18n.t('account_requests.user_exists_warning')
       end
       render json: response, status: :created
     else
@@ -60,7 +60,7 @@ def update
   def destroy
     @account_request = AccountRequest.find(params[:id])
     @account_request.destroy
-    render json: { message: 'Account Request deleted' }, status: :no_content
+    render json: { message: I18n.t('account_requests.delete_success') }, status: :no_content
   rescue ActiveRecord::RecordNotFound => e
       render json: { error: e.message }, status: :not_found
   end
@@ -74,7 +74,7 @@ def account_request_params
       params[:account_request][:status] = 'Under Review'
     # For Approval or Rejection of an existing request, raise error if user sends a status other than Approved or Rejected
     elsif !['Approved', 'Rejected'].include?(params[:account_request][:status])
-      raise StandardError, 'Status can only be Approved or Rejected'
+      raise StandardError, I18n.t('account_requests.status_error')
     end
     params.require(:account_request).permit(:username, :full_name, :email, :status, :introduction, :role_id, :institution_id)
   end
@@ -82,12 +82,12 @@ def account_request_params
   # Create a new user if account request is approved
   def create_approved_user
     if User.exists?(email: @account_request.email)
-      render json: { error: 'A user with this email already exists. Cannot approve the account request.' }, status: :unprocessable_entity
+      render json: { error: I18n.t('account_requests.user_exists') }, status: :unprocessable_entity
       return
     end
     @new_user = User.new(name: @account_request.username, role_id: @account_request.role_id, institution_id: @account_request.institution_id, full_name: @account_request.full_name, email: @account_request.email, password: 'password')
     if @new_user.save
-      render json: { success: 'Account Request Approved and User successfully created.', user: @new_user}, status: :ok
+      render json: { success: I18n.t('account_requests.create_success'), user: @new_user }, status: :ok
     else
       render json: @new_user.errors, status: :unprocessable_entity
     end
diff --git a/app/controllers/api/v1/assignments_controller.rb b/app/controllers/api/v1/assignments_controller.rb
index fdaf9bc75..bca8f677e 100644
--- a/app/controllers/api/v1/assignments_controller.rb
+++ b/app/controllers/api/v1/assignments_controller.rb
@@ -34,7 +34,7 @@ def update
   end
 
   def not_found
-    render json: { error: "Assignment not found" }, status: :not_found
+    render json: { error: I18n.t('assignment.not_found') }, status: :not_found
   end
 
   # DELETE /api/v1/assignments/:id
@@ -42,12 +42,12 @@ def destroy
     assignment = Assignment.find_by(id: params[:id])
     if assignment
       if assignment.destroy
-        render json: { message: "Assignment deleted successfully!" }, status: :ok
+        render json: { message: I18n.t('assignment.deleted_successfully') }, status: :ok
       else
-        render json: { error: "Failed to delete assignment", details: assignment.errors.full_messages }, status: :unprocessable_entity
+        render json: { error: I18n.t('assignment.failed_to_delete'), details: assignment.errors.full_messages }, status: :unprocessable_entity
       end
     else
-      render json: { error: "Assignment not found" }, status: :not_found
+      render json: { error: I18n.t('assignment.not_found') }, status: :not_found
     end
   end
   
@@ -55,7 +55,7 @@ def destroy
   def add_participant
     assignment = Assignment.find_by(id: params[:assignment_id])
     if assignment.nil?
-      render json: { error: "Assignment not found" }, status: :not_found
+      render json: { error: I18n.t('assignment.not_found') }, status: :not_found
     else
       new_participant = assignment.add_participant(params[:user_id])
       if new_participant.save
@@ -73,12 +73,12 @@ def remove_participant
     if user && assignment
       assignment.remove_participant(user.id)
       if assignment.save
-        render json: { message: "Participant removed successfully!" }, status: :ok
+        render json: { message: I18n.t('assignment.participant_removed') }, status: :ok
       else
         render json: assignment.errors, status: :unprocessable_entity
       end
     else
-      not_found_message = user ? "Assignment not found" : "User not found"
+      not_found_message = user ? I18n.t('assignment.user_not_found') : I18n.t('assignment.not_found')
       render json: { error: not_found_message }, status: :not_found
     end
   end
@@ -88,7 +88,7 @@ def remove_participant
   def remove_assignment_from_course
     assignment = Assignment.find(params[:assignment_id])
     if assignment.nil?
-      render json: { error: "Assignment not found" }, status: :not_found
+      render json: { error: I18n.t('assignment.not_found') }, status: :not_found
     else
       assignment = assignment.remove_assignment_from_course
       if assignment.save
@@ -112,7 +112,7 @@ def assign_course
         render json: assignment.errors, status: :unprocessable_entity
       end
     else
-      not_found_message = course ? "Assignment not found" : "Course not found"
+      not_found_message = course ? I18n.t('assignment.course_not_found') : I18n.t('assignment.not_found')
       render json: { error: not_found_message }, status: :not_found
     end
   end
@@ -121,7 +121,7 @@ def assign_course
   def copy_assignment
     assignment = Assignment.find_by(id: params[:assignment_id])
     if assignment.nil?
-      render json: { error: "Assignment not found" }, status: :not_found
+      render json: { error: I18n.t('assignment.not_found') }, status: :not_found
     else
       new_assignment = assignment.copy
       if new_assignment.save
@@ -137,7 +137,7 @@ def copy_assignment
   def show_assignment_details
     assignment = Assignment.find_by(id: params[:assignment_id])
     if assignment.nil?
-      render json: { error: "Assignment not found" }, status: :not_found
+      render json: { error: I18n.t('assignment.not_found') }, status: :not_found
     else
       render json: {
         id: assignment.id,
@@ -155,7 +155,7 @@ def show_assignment_details
   def has_topics
     assignment = Assignment.find_by(id: params[:assignment_id])
     if assignment.nil?
-      render json: { error: "Assignment not found" }, status: :not_found
+      render json: { error: I18n.t('assignment.not_found') }, status: :not_found
     else
       render json: assignment.topics?, status: :ok
     end
@@ -166,7 +166,7 @@ def has_topics
   def team_assignment
     assignment = Assignment.find_by(id: params[:assignment_id])
     if assignment.nil?
-      render json: { error: "Assignment not found" }, status: :not_found
+      render json: { error: I18n.t('assignment.not_found') }, status: :not_found
     else
       render json: assignment.team_assignment?, status: :ok
     end
@@ -178,7 +178,7 @@ def valid_num_review
     assignment = Assignment.find_by(id: params[:assignment_id])
     review_type = params[:review_type]
     if assignment.nil?
-      render json: { error: "Assignment not found" }, status: :not_found
+      render json: { error: I18n.t('assignment.not_found') }, status: :not_found
     else
       render json: assignment.valid_num_review(review_type), status: :ok
     end
@@ -189,7 +189,7 @@ def valid_num_review
   def has_teams
     assignment = Assignment.find_by(id: params[:assignment_id])
     if assignment.nil?
-      render json: { error: "Assignment not found" }, status: :not_found
+      render json: { error: I18n.t('assignment.not_found') }, status: :not_found
     else
       render json: assignment.teams?, status: :ok
     end
@@ -200,12 +200,12 @@ def has_teams
   def varying_rubrics_by_round?
     assignment = Assignment.find_by(id: params[:assignment_id])
     if assignment.nil?
-      render json: { error: "Assignment not found" }, status: :not_found
+      render json: { error: I18n.t('assignment.not_found') }, status: :not_found
     else
       if AssignmentQuestionnaire.exists?(assignment_id: assignment.id)
         render json: assignment.varying_rubrics_by_round?, status: :ok
       else
-        render json: { error: "No questionnaire/rubric exists for this assignment." }, status: :not_found
+        render json: { error: I18n.t('assignment.no_questionnaire') }, status: :not_found
       end
     end
   end
diff --git a/app/controllers/api/v1/bookmarks_controller.rb b/app/controllers/api/v1/bookmarks_controller.rb
index 912d58d00..2e5e96dd5 100644
--- a/app/controllers/api/v1/bookmarks_controller.rb
+++ b/app/controllers/api/v1/bookmarks_controller.rb
@@ -49,7 +49,7 @@ def update
 
   # Handle the case when an invalid bookmark id is being passed
   def not_found
-    render json: { error: "Couldn't find Bookmark" }, status: :not_found
+    render json: { error: I18n.t('bookmarks.not_found') }, status: :not_found
   end
 
   # Destroy method deletes the bookmark object with id- {:id}
diff --git a/app/controllers/api/v1/courses_controller.rb b/app/controllers/api/v1/courses_controller.rb
index 2529613da..473ad0608 100644
--- a/app/controllers/api/v1/courses_controller.rb
+++ b/app/controllers/api/v1/courses_controller.rb
@@ -45,7 +45,7 @@ def update
   # Delete a course
   def destroy
     @course.destroy
-    render json: { message: "Course with id #{params[:id]}, deleted" }, status: :no_content
+    render json: { message: I18n.t('course.deleted', id: params[:id]) }, status: :no_content
   end
 
   # Adds a Teaching Assistant to the course
@@ -69,7 +69,7 @@ def view_tas
   def remove_ta
     result = @course.remove_ta(params[:ta_id])
     if result[:success]
-      render json: { message: "The TA #{result[:ta_name]} has been removed." }, status: :ok
+      render json: { message: I18n.t('course.ta_removed', ta_name: result[:ta_name]) }, status: :ok
     else
       render json: { status: "error", message: result[:message] }, status: :not_found
     end
@@ -80,9 +80,9 @@ def copy
     # existing_course = Course.find(params[:id])
     success = @course.copy_course
     if success
-      render json: { message: "The course #{@course.name} has been successfully copied" }, status: :ok
+      render json: { message: I18n.t('course.copy_success', name: @course.name) }, status: :ok
     else
-      render json: { message: "The course was not able to be copied" }, status: :unprocessable_entity
+      render json: { message: I18n.t('course.copy_failure') }, status: :unprocessable_entity
     end
   end
 
@@ -99,10 +99,10 @@ def course_params
   end
 
   def course_not_found
-    render json: { error: "Course with id #{params[:id]} not found" }, status: :not_found
+    render json: { error: I18n.t('course.not_found', id: params[:id]) }, status: :not_found
   end
 
   def parameter_missing
-    render json: { error: "Parameter missing" }, status: :unprocessable_entity
+    render json: { error: I18n.t('course.parameter_missing') }, status: :unprocessable_entity
   end
 end
diff --git a/app/controllers/api/v1/institutions_controller.rb b/app/controllers/api/v1/institutions_controller.rb
index fa22de3b2..cb5d77e18 100644
--- a/app/controllers/api/v1/institutions_controller.rb
+++ b/app/controllers/api/v1/institutions_controller.rb
@@ -41,7 +41,7 @@ def update
   def destroy
     @institution = Institution.find(params[:id])
     @institution.destroy
-    render json: { message: 'Institution deleted' }, status: :ok
+    render json: { message: I18n.t('institution.deleted') }, status: :ok
   end
 
   private
@@ -52,6 +52,6 @@ def institution_params
   end
 
   def institution_not_found
-    render json: { error: 'Institution not found' }, status: :not_found
+    render json: { error: I18n.t('institution.not_found') }, status: :not_found
   end
 end
\ No newline at end of file
diff --git a/app/controllers/api/v1/join_team_requests_controller.rb b/app/controllers/api/v1/join_team_requests_controller.rb
index 57a8ed383..0dc5fcac0 100644
--- a/app/controllers/api/v1/join_team_requests_controller.rb
+++ b/app/controllers/api/v1/join_team_requests_controller.rb
@@ -19,7 +19,7 @@ def action_allowed?
   # gets a list of all the join team requests
   def index
     unless @current_user.administrator?
-      return render json: { errors: 'Unauthorized' }, status: :unauthorized
+      return render json: { errors: I18n.t('join_team_requests.unauthorized') }, status: :unauthorized
     end
     join_team_requests = JoinTeamRequest.all
     render json: join_team_requests, status: :ok
@@ -42,7 +42,7 @@ def create
     team = Team.find(params[:team_id])
 
     if team.participants.include?(participant)
-      render json: { error: 'You already belong to the team' }, status: :unprocessable_entity
+      render json: { error: I18n.t('join_team_requests.already_in_team') }, status: :unprocessable_entity
     elsif participant
       join_team_request.participant_id = participant.id
       if join_team_request.save
@@ -51,7 +51,7 @@ def create
         render json: { errors: join_team_request.errors.full_messages }, status: :unprocessable_entity
       end
     else
-      render json: { errors: 'Participant not found' }, status: :unprocessable_entity
+      render json: { errors: I18n.t('join_team_requests.participant_not_found') }, status: :unprocessable_entity
     end
   end
 
@@ -59,7 +59,7 @@ def create
   # Updates a join team request
   def update
     if @join_team_request.update(join_team_request_params)
-      render json: { message: 'JoinTeamRequest was successfully updated' }, status: :ok
+      render json: { message: I18n.t('join_team_requests.update_success') }, status: :ok
     else
       render json: { errors: @join_team_request.errors.full_messages }, status: :unprocessable_entity
     end
@@ -69,9 +69,9 @@ def update
   # delete a join team request
   def destroy
     if @join_team_request.destroy
-      render json: { message: 'JoinTeamRequest was successfully deleted' }, status: :ok
+      render json: { message: I18n.t('join_team_requests.delete_success') }, status: :ok
     else
-      render json: { errors: 'Failed to delete JoinTeamRequest' }, status: :unprocessable_entity
+      render json: { errors: I18n.t('join_team_requests.delete_failure') }, status: :unprocessable_entity
     end
   end
 
@@ -79,7 +79,7 @@ def destroy
   def decline
     @join_team_request.status = DECLINED
     if @join_team_request.save
-      render json: { message: 'JoinTeamRequest declined successfully' }, status: :ok
+      render json: { message: I18n.t('join_team_requests.decline_success') }, status: :ok
     else
       render json: { errors: @join_team_request.errors.full_messages }, status: :unprocessable_entity
     end
@@ -90,7 +90,7 @@ def decline
   def check_team_status
     team = Team.find(params[:team_id])
     if team.full?
-      render json: { message: 'This team is full.' }, status: :unprocessable_entity
+      render json: { message: I18n.t('join_team_requests.team_full') }, status: :unprocessable_entity
     end
   end
 
diff --git a/app/controllers/api/v1/participants_controller.rb b/app/controllers/api/v1/participants_controller.rb
index 675ae7a1e..5410eb76b 100644
--- a/app/controllers/api/v1/participants_controller.rb
+++ b/app/controllers/api/v1/participants_controller.rb
@@ -113,9 +113,9 @@ def destroy
       render json: { error: 'Not Found' }, status: :not_found
     elsif participant.destroy
       successful_deletion_message = if params[:team_id].nil?
-                                      "Participant #{params[:id]} in Assignment #{params[:assignment_id]} has been deleted successfully!"
+                                      I18n.t('participants.destroy.success_assignment', id: params[:id], assignment_id: params[:assignment_id])
                                     else
-                                      "Participant #{params[:id]} in Team #{params[:team_id]} of Assignment #{params[:assignment_id]} has been deleted successfully!"
+                                      I18n.t('participants.destroy.success_team', id: params[:id], team_id: params[:team_id], assignment_id: params[:assignment_id])
                                     end
       render json: { message: successful_deletion_message }, status: :ok
     else
@@ -154,7 +154,7 @@ def filter_assignment_participants(assignment)
   def find_user
     user_id = params[:user_id]
     user = User.find_by(id: user_id)
-    render json: { error: 'User not found' }, status: :not_found unless user
+    render json: { error: I18n.t('participants.user_not_found') }, status: :not_found unless user
     user
   end
 
@@ -163,7 +163,7 @@ def find_user
   def find_assignment
     assignment_id = params[:assignment_id]
     assignment = Assignment.find_by(id: assignment_id)
-    render json: { error: 'Assignment not found' }, status: :not_found unless assignment
+    render json: { error: I18n.t('participants.assignment_not_found') }, status: :not_found unless assignment
     assignment
   end
 
@@ -172,7 +172,7 @@ def find_assignment
   def find_participant
     participant_id = params[:id]
     participant = Participant.find_by(id: participant_id)
-    render json: { error: 'Participant not found' }, status: :not_found unless participant
+    render json: { error: I18n.t('participants.not_found') }, status: :not_found unless participant
     participant
   end
 
@@ -184,12 +184,12 @@ def validate_authorization
     authorization = authorization.downcase if authorization.present?
 
     unless authorization
-      render json: { error: 'authorization is required' }, status: :unprocessable_entity
+      render json: { error: I18n.t('participants.authorization_required') }, status: :unprocessable_entity
       return
     end
 
     unless valid_authorizations.include?(authorization)
-      render json: { error: 'authorization not valid. Valid authorizations are: Reader, Reviewer, Submitter, Mentor' },
+      render json: { error: I18n.t('participants.authorization_invalid') },
              status: :unprocessable_entity
       return
     end
diff --git a/app/controllers/api/v1/roles_controller.rb b/app/controllers/api/v1/roles_controller.rb
index 55fa081f0..5a202c13a 100644
--- a/app/controllers/api/v1/roles_controller.rb
+++ b/app/controllers/api/v1/roles_controller.rb
@@ -43,7 +43,7 @@ def destroy
     role = Role.find(params[:id])
     role_name = role.name
     role.destroy
-    render json: { message: "Role #{role_name} with id #{params[:id]} deleted successfully!" }, status: :no_content
+    render json: { message: I18n.t('roles.destroy.success', role_name: role_name, id: params[:id]) }, status: :no_content
   end
 
   def subordinate_roles
@@ -64,6 +64,6 @@ def role_params
   # end
 
   def parameter_missing
-    render json: { error: 'Parameter missing' }, status: :unprocessable_entity
+    render json: { error: I18n.t('roles.parameter_missing') }, status: :unprocessable_entity
   end
-end
+end
\ No newline at end of file
diff --git a/app/controllers/api/v1/sign_up_topics_controller.rb b/app/controllers/api/v1/sign_up_topics_controller.rb
index a736f3eaa..cf1929a8c 100644
--- a/app/controllers/api/v1/sign_up_topics_controller.rb
+++ b/app/controllers/api/v1/sign_up_topics_controller.rb
@@ -5,7 +5,7 @@ class Api::V1::SignUpTopicsController < ApplicationController
   # Retrieve SignUpTopics by two query parameters - assignment_id (compulsory) and an array of topic_ids (optional)
   def index
     if params[:assignment_id].nil?
-      render json: { message: 'Assignment ID is required!' }, status: :unprocessable_entity
+      render json: { message: I18n.t('sign_up_topics.assignment_id_required') }, status: :unprocessable_entity
     elsif params[:topic_ids].nil?
       @sign_up_topics = SignUpTopic.where(assignment_id: params[:assignment_id])
       render json: @sign_up_topics, status: :ok
@@ -25,8 +25,7 @@ def create
     @assignment = Assignment.find(params[:sign_up_topic][:assignment_id])
     @sign_up_topic.micropayment = params[:micropayment] if @assignment.microtask?
     if @sign_up_topic.save
-      # undo_link "The topic: \"#{@sign_up_topic.topic_name}\" has been created successfully. "
-      render json: { message: "The topic: \"#{@sign_up_topic.topic_name}\" has been created successfully. " }, status: :created
+      render json: { message: I18n.t('sign_up_topics.create_success', topic_name: @sign_up_topic.topic_name) }, status: :created
     else
       render json: { message: @sign_up_topic.errors }, status: :unprocessable_entity
     end
@@ -36,7 +35,7 @@ def create
   # updates parameters present in sign_up_topic_params.
   def update
     if @sign_up_topic.update(sign_up_topic_params)
-      render json: { message: "The topic: \"#{@sign_up_topic.topic_name}\" has been updated successfully. " }, status: 200
+      render json: { message: I18n.t('sign_up_topics.update_success', topic_name: @sign_up_topic.topic_name) }, status: :ok
     else
       render json: @sign_up_topic.errors, status: :unprocessable_entity
     end
@@ -54,7 +53,7 @@ def destroy
     # render json: {message: @sign_up_topic}
     # filters topics based on assignment id (required) and topic identifiers (optional)
     if params[:assignment_id].nil?
-      render json: { message: 'Assignment ID is required!' }, status: :unprocessable_entity
+      render json: { message: I18n.t('sign_up_topics.assignment_id_required') }, status: :unprocessable_entity
     elsif params[:topic_ids].nil?
       @sign_up_topics = SignUpTopic.where(assignment_id: params[:assignment_id])
       # render json: @sign_up_topics, status: :ok
@@ -64,7 +63,7 @@ def destroy
     end
 
     if @sign_up_topics.each(&:delete)
-      render json: { message: "The topic has been deleted successfully. " }, status: :no_content
+      render json: { message: I18n.t('sign_up_topics.delete_success') }, status: :no_content
     else
       render json: @sign_up_topic.errors, status: :unprocessable_entity
     end
diff --git a/app/controllers/api/v1/signed_up_teams_controller.rb b/app/controllers/api/v1/signed_up_teams_controller.rb
index 97ada5a24..0ac537d98 100644
--- a/app/controllers/api/v1/signed_up_teams_controller.rb
+++ b/app/controllers/api/v1/signed_up_teams_controller.rb
@@ -16,7 +16,7 @@ def create; end
   def update
     @signed_up_team = SignedUpTeam.find(params[:id])
     if @signed_up_team.update(signed_up_teams_params)
-      render json: { message: "The team has been updated successfully. " }, status: 200
+      render json: { message: I18n.t('signed_up_teams.update_success') }, status: :ok
     else
       render json: @signed_up_team.errors, status: :unprocessable_entity
     end
@@ -29,7 +29,7 @@ def sign_up
     topic_id = params[:topic_id]
     @signed_up_team = SignedUpTeam.create_signed_up_team(topic_id, team_id)
     if @signed_up_team
-      render json: { message: "Signed up team successful!" }, status: :created
+      render json: { message: I18n.t('signed_up_teams.create_success') }, status: :created
     else
       render json: { message: @signed_up_team.errors }, status: :unprocessable_entity
     end
@@ -48,7 +48,7 @@ def sign_up_student
     @signed_up_team = SignedUpTeam.create_signed_up_team(topic_id, team_id)
     # create(topic_id, team_id)
     if @signed_up_team
-      render json: { message: "Signed up team successful!" }, status: :created
+      render json: { message: I18n.t('signed_up_teams.create_success') }, status: :created
     else
       render json: { message: @signed_up_team.errors }, status: :unprocessable_entity
     end
@@ -58,7 +58,7 @@ def sign_up_student
   def destroy
     @signed_up_team = SignedUpTeam.find(params[:id])
     if SignedUpTeam.delete_signed_up_team(@signed_up_team.team_id)
-      render json: { message: 'Signed up teams was deleted successfully!' }, status: :ok
+      render json: { message: I18n.t('signed_up_teams.delete_success') }, status: :ok
     else
       render json: @signed_up_team.errors, status: :unprocessable_entity
     end
diff --git a/app/controllers/api/v1/users_controller.rb b/app/controllers/api/v1/users_controller.rb
index 086376556..d3475c978 100644
--- a/app/controllers/api/v1/users_controller.rb
+++ b/app/controllers/api/v1/users_controller.rb
@@ -39,7 +39,7 @@ def update
   def destroy
     user = User.find(params[:id])
     user.destroy
-    render json: { message: "User #{user.name} with id #{params[:id]} deleted successfully!" }, status: :no_content
+    render json: { message: I18n.t('users.destroy.success', name: user.name, id: params[:id]) }, status: :no_content
   end
 
   # GET /api/v1/users/institution/:id
@@ -57,7 +57,7 @@ def institution_users
   def managed_users
     parent = User.find(params[:id])
     if parent.student?
-      render json: { error: 'Students do not manage any users' }, status: :unprocessable_entity
+      render json: { error: I18n.t('users.managed_users.student_error') }, status: :unprocessable_entity
       return
     end
     parent = User.instantiate(parent)
@@ -86,10 +86,10 @@ def user_params
   end
 
   def user_not_found
-    render json: { error: "User with id #{params[:id]} not found" }, status: :not_found
+    render json: { error: I18n.t('users.not_found', id: params[:id]) }, status: :not_found
   end
 
   def parameter_missing
-    render json: { error: 'Parameter missing' }, status: :unprocessable_entity
+    render json: { error: I18n.t('users.parameter_missing') }, status: :unprocessable_entity
   end
 end
diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index 12ffcf261..c0f3317e0 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -3,5 +3,12 @@ class ApplicationController < ActionController::API
   include JwtToken
   
   before_action :authorize
+  before_action :set_locale
+
+  private
+
+  def set_locale
+    I18n.locale = current_user.try(:locale) || I18n.default_locale
+  end
 
 end
diff --git a/config/application.rb b/config/application.rb
index 4bd4ca23e..876ee6278 100644
--- a/config/application.rb
+++ b/config/application.rb
@@ -30,5 +30,10 @@ class Application < Rails::Application
     # Skip views, helpers and assets when generating a new resource.
     config.api_only = true
     config.cache_store = :redis_store, ENV['CACHE_STORE'], { expires_in: 3.days, raise_errors: false }
+
+    # Internationalization (i18n) Settings
+    config.i18n.default_locale = :en_US  
+    config.i18n.available_locales = [:en_US, :hi_IN]  
+    config.i18n.fallbacks = [:en_US]  
   end
 end
diff --git a/config/locales/en.yml b/config/locales/en.yml
deleted file mode 100644
index 8ca56fc74..000000000
--- a/config/locales/en.yml
+++ /dev/null
@@ -1,33 +0,0 @@
-# Files in the config/locales directory are used for internationalization
-# and are automatically loaded by Rails. If you want to use locales other
-# than English, add the necessary files in this directory.
-#
-# To use the locales, use `I18n.t`:
-#
-#     I18n.t "hello"
-#
-# In views, this is aliased to just `t`:
-#
-#     <%= t("hello") %>
-#
-# To use a different locale, set it with `I18n.locale`:
-#
-#     I18n.locale = :es
-#
-# This would use the information in config/locales/es.yml.
-#
-# The following keys must be escaped otherwise they will not be retrieved by
-# the default I18n backend:
-#
-# true, false, on, off, yes, no
-#
-# Instead, surround them with single quotes.
-#
-# en:
-#   "true": "foo"
-#
-# To learn more, please read the Rails Internationalization guide
-# available at https://guides.rubyonrails.org/i18n.html.
-
-en:
-  hello: "Hello world"
diff --git a/config/locales/en_US.yml b/config/locales/en_US.yml
new file mode 100644
index 000000000..5deb952ac
--- /dev/null
+++ b/config/locales/en_US.yml
@@ -0,0 +1,97 @@
+# Files in the config/locales directory are used for internationalization
+# and are automatically loaded by Rails. If you want to use locales other
+# than English, add the necessary files in this directory.
+#
+# To use the locales, use `I18n.t`:
+#
+#     I18n.t "hello"
+#
+# In views, this is aliased to just `t`:
+#
+#     <%= t("hello") %>
+#
+# To use a different locale, set it with `I18n.locale`:
+#
+#     I18n.locale = :es
+#
+# This would use the information in config/locales/es.yml.
+#
+# The following keys must be escaped otherwise they will not be retrieved by
+# the default I18n backend:
+#
+# true, false, on, off, yes, no
+#
+# Instead, surround them with single quotes.
+#
+# en:
+#   "true": "foo"
+#
+# To learn more, please read the Rails Internationalization guide
+# available at https://guides.rubyonrails.org/i18n.html.
+
+en_US:
+      assignment:
+            not_found: Assignment not found
+            deleted_successfully: Assignment deleted successfully!
+            failed_to_delete: Failed to delete assignment
+            participant_removed: Participant removed successfully!
+            user_not_found: User not found
+            course_not_found: Course not found
+            no_questionnaire: No questionnaire/rubric exists for this assignment.
+      institution:
+            not_found: "Institution not found"
+            deleted: "Institution deleted"
+      course:
+            not_found: "Course with id %{id} not found"
+            deleted: "Course with id %{id}, deleted"
+            ta_removed: "The TA %{ta_name} has been removed."
+            copy_success: "The course %{name} has been successfully copied"
+            copy_failure: "The course was not able to be copied"
+            parameter_missing: "Parameter missing"
+      roles:
+        destroy:
+          success: "Role %{role_name} with id %{id} deleted successfully!"
+        parameter_missing: "Parameter missing"
+      participants:
+        destroy:
+          success_assignment: "Participant %{id} in Assignment %{assignment_id} has been deleted successfully!"
+          success_team: "Participant %{id} in Team %{team_id} of Assignment %{assignment_id} has been deleted successfully!"
+        not_found: "Participant not found"
+        user_not_found: "User not found"
+        assignment_not_found: "Assignment not found"
+        authorization_required: "Authorization is required"
+        authorization_invalid: "Authorization not valid. Valid authorizations are: Reader, Reviewer, Submitter, Mentor"
+      users:
+        destroy:
+          success: "User %{name} with id %{id} deleted successfully!"
+        not_found: "User with id %{id} not found"
+        parameter_missing: "Parameter missing"
+        managed_users:
+          student_error: "Students do not manage any users"
+      bookmarks:
+        not_found: "Couldn't find Bookmark"  
+      join_team_requests:
+        unauthorized: "Unauthorized"
+        already_in_team: "You already belong to the team"
+        participant_not_found: "Participant not found"
+        update_success: "JoinTeamRequest was successfully updated"
+        update_failure: "Failed to update JoinTeamRequest"
+        delete_success: "JoinTeamRequest was successfully deleted"
+        delete_failure: "Failed to delete JoinTeamRequest"
+        decline_success: "JoinTeamRequest declined successfully"
+        team_full: "This team is full."   
+      signed_up_teams:
+        create_success: "Signed up team successful!"
+        update_success: "The team has been updated successfully."
+        delete_success: "Signed up team was deleted successfully!"
+      account_requests:
+        user_exists: "A user with this email already exists. Cannot approve the account request."
+        create_success: "Account Request Approved and User successfully created."
+        delete_success: "Account Request deleted"
+        status_error: "Status can only be Approved or Rejected"
+        user_exists_warning: "WARNING: User with this email already exists!"
+      sign_up_topics:
+        assignment_id_required: "Assignment ID is required!"
+        create_success: "The topic: \"%{topic_name}\" has been created successfully."
+        update_success: "The topic: \"%{topic_name}\" has been updated successfully."
+        delete_success: "The topic has been deleted successfully."
diff --git a/config/locales/hi_IN.yml b/config/locales/hi_IN.yml
new file mode 100644
index 000000000..58702a4ae
--- /dev/null
+++ b/config/locales/hi_IN.yml
@@ -0,0 +1,66 @@
+hi_IN:
+  assignment:
+    not_found: असाइनमेंट नहीं मिला
+    deleted_successfully: असाइनमेंट सफलतापूर्वक हटा दिया गया!
+    failed_to_delete: असाइनमेंट को हटाने में विफल
+    participant_removed: प्रतिभागी को सफलतापूर्वक हटा दिया गया!
+    user_not_found: उपयोगकर्ता नहीं मिला
+    course_not_found: कोर्स नहीं मिला
+    no_questionnaire: इस असाइनमेंट के लिए कोई प्रश्नावली/रूब्रिक मौजूद नहीं है।
+  course:
+    not_found: "कोर्स आईडी %{id} के साथ नहीं मिला"
+    deleted: "कोर्स आईडी %{id} के साथ हटा दिया गया"
+    ta_removed: "टीए %{ta_name} को हटा दिया गया है।"
+    copy_success: "कोर्स %{name} को सफलतापूर्वक कॉपी किया गया है"
+    copy_failure: "कोर्स को कॉपी नहीं किया जा सका"
+    parameter_missing: "पैरामीटर गायब है"
+  institution:
+    not_found: "संस्थान नहीं मिला"
+    deleted: "संस्थान हटा दिया गया"
+  roles:
+    destroy:
+      success: "भूमिका %{role_name} आईडी %{id} के साथ सफलतापूर्वक हटा दी गई!"
+    parameter_missing: "पैरामीटर गायब है"
+  participants:
+    destroy:
+      success_assignment: "असाइनमेंट %{assignment_id} में प्रतिभागी %{id} को सफलतापूर्वक हटा दिया गया है!"
+      success_team: "असाइनमेंट %{assignment_id} की टीम %{team_id} में प्रतिभागी %{id} को सफलतापूर्वक हटा दिया गया है!"
+    not_found: "प्रतिभागी नहीं मिला"
+    user_not_found: "उपयोगकर्ता नहीं मिला"
+    assignment_not_found: "असाइनमेंट नहीं मिला"
+    authorization_required: "प्राधिकरण आवश्यक है"
+    authorization_invalid: "प्राधिकरण मान्य नहीं है। मान्य प्राधिकरण हैं: पाठक, समीक्षक, प्रस्तुतकर्ता, संरक्षक"
+  users:
+    destroy:
+      success: "उपयोगकर्ता %{name} आईडी %{id} के साथ सफलतापूर्वक हटा दिया गया है!"
+    not_found: "आईडी %{id} के साथ उपयोगकर्ता नहीं मिला"
+    parameter_missing: "पैरामीटर गायब है"
+    managed_users:
+      student_error: "छात्र किसी भी उपयोगकर्ताओं का प्रबंधन नहीं करते हैं"
+  bookmarks:
+    not_found: "बुकमार्क नहीं मिला"
+  join_team_requests:
+    unauthorized: "अनधिकृत"
+    already_in_team: "आप पहले से ही टीम में हैं"
+    participant_not_found: "प्रतिभागी नहीं मिला"
+    update_success: "JoinTeamRequest सफलतापूर्वक अपडेट किया गया"
+    update_failure: "JoinTeamRequest को अपडेट करने में विफल"
+    delete_success: "JoinTeamRequest सफलतापूर्वक हटा दिया गया"
+    delete_failure: "JoinTeamRequest को हटाने में विफल"
+    decline_success: "JoinTeamRequest को सफलतापूर्वक अस्वीकार कर दिया गया"
+    team_full: "यह टीम पूरी हो चुकी है।"  
+  signed_up_teams:
+    create_success: "टीम सफलतापूर्वक साइन अप हो गई!"
+    update_success: "टीम को सफलतापूर्वक अपडेट कर दिया गया है।"
+    delete_success: "साइन अप की गई टीम को सफलतापूर्वक हटा दिया गया है!"   
+  account_requests:
+    user_exists: "इस ईमेल के साथ एक उपयोगकर्ता पहले से मौजूद है। खाता अनुरोध को स्वीकृत नहीं किया जा सकता।"
+    create_success: "खाता अनुरोध स्वीकृत और उपयोगकर्ता सफलतापूर्वक बनाया गया।"
+    delete_success: "खाता अनुरोध हटा दिया गया"
+    status_error: "स्थिति केवल स्वीकृत या अस्वीकृत हो सकती है"
+    user_exists_warning: "चेतावनी: इस ईमेल के साथ एक उपयोगकर्ता पहले से मौजूद है!"
+  sign_up_topics:
+    assignment_id_required: "असाइनमेंट आईडी आवश्यक है!"
+    create_success: "विषय: \"%{topic_name}\" सफलतापूर्वक बनाया गया है।"
+    update_success: "विषय: \"%{topic_name}\" सफलतापूर्वक अपडेट किया गया है।"
+    delete_success: "विषय को सफलतापूर्वक हटा दिया गया है।"
\ No newline at end of file
diff --git a/spec/controllers/api/v1/assignments_spec.rb b/spec/controllers/api/v1/assignments_spec.rb
new file mode 100644
index 000000000..a37b2367d
--- /dev/null
+++ b/spec/controllers/api/v1/assignments_spec.rb
@@ -0,0 +1,78 @@
+require 'rails_helper'
+
+RSpec.describe 'Assignments API', type: :request do
+
+  let!(:instructor) { User.create!(name: "Instructor", email: "instructor@example.com", password: "password123") }
+  let!(:course) { Course.create!(title: "Test Course", description: "Some desc") } # Add this line!
+  
+  let!(:valid_attributes) do
+    {
+      name: "Test Assignment",
+      description: "Test Desc",
+      due_date: "2025-12-31",
+      instructor_id: instructor.id,
+      course_id: course.id,
+      max_team_size: 2
+    }
+  end
+
+  let!(:assignment) do
+    assignment = Assignment.new(valid_attributes)
+     unless assignment.valid?
+         puts "Validation Errors: #{assignment.errors.full_messages}"
+     end
+    assignment.save!
+    assignment
+  end
+          
+  before do
+    allow_any_instance_of(Api::V1::AssignmentsController).to receive(:authenticate_user!).and_return(true)
+  end
+
+  describe 'GET /api/v1/assignments' do
+    it 'returns all assignments' do
+      get '/api/v1/assignments'
+      expect(response).to have_http_status(:ok)
+      json = JSON.parse(response.body)
+      expect(json).to be_an(Array)
+      expect(json.first['name']).to eq('Test Assignment')
+    end
+  end
+
+  describe 'GET /api/v1/assignments/:id' do
+    it 'returns a specific assignment' do
+      get "/api/v1/assignments/#{assignment.id}"
+      expect(response).to have_http_status(:ok)
+      json = JSON.parse(response.body)
+      expect(json['id']).to eq(assignment.id)
+    end
+  end
+
+  describe 'POST /api/v1/assignments' do
+    it 'creates a new assignment with valid params' do
+      expect {
+        post '/api/v1/assignments', params: { assignment: { name: 'New Assignment', description: 'Desc', due_date: '2025-11-30', instructor_id: instructor.id, course_id: course.id, max_team_size: 2 } }, as: :json
+      }.to change(Assignment, :count).by(1)
+      expect(response).to have_http_status(:created)
+    end
+  end
+
+  describe 'PUT /api/v1/assignments/:id' do
+    it 'updates an assignment' do
+      put "/api/v1/assignments/#{assignment.id}", params: { assignment: { name: 'Updated Name' } }, as: :json
+      expect(response).to have_http_status(:ok)
+      assignment.reload
+      expect(assignment.name).to eq('Updated Name')
+    end
+  end
+
+  describe 'DELETE /api/v1/assignments/:id' do
+    it 'deletes an assignment' do
+      DueDate.where(parent: assignment).delete_all
+      expect {
+        delete "/api/v1/assignments/#{assignment.id}"
+      }.to change(Assignment, :count).by(-1)
+      expect(response).to have_http_status(:no_content)
+    end
+  end
+end
diff --git a/spec/controllers/api/v1/course_controller_spec.rb b/spec/controllers/api/v1/course_controller_spec.rb
new file mode 100644
index 000000000..b3f4e5029
--- /dev/null
+++ b/spec/controllers/api/v1/course_controller_spec.rb
@@ -0,0 +1,81 @@
+require 'rails_helper'
+
+RSpec.describe "Courses", type: :request do
+  let!(:course) { Course.create(title: "Ruby on Rails", description: "Learn Rails") }
+
+  describe "GET /courses" do
+    it "returns a successful response" do
+      get courses_path
+      expect(response).to have_http_status(:ok)
+      expect(response.body).to include("Ruby on Rails")
+    end
+  end
+
+  describe "GET /courses/:id" do
+    context "when the course exists" do
+      it "returns the course details" do
+        get course_path(course)
+        expect(response).to have_http_status(:ok)
+        expect(response.body).to include("Ruby on Rails")
+      end
+    end
+
+    context "when the course does not exist" do
+      it "returns a 404 status" do
+        get course_path(id: 999)
+        expect(response).to have_http_status(:not_found)
+      end
+    end
+  end
+
+  describe "POST /courses" do
+    context "with valid parameters" do
+      it "creates a new course" do
+        course_params = { course: { title: "RSpec Testing", description: "Learn RSpec" } }
+        expect {
+          post courses_path, params: course_params
+        }.to change(Course, :count).by(1)
+        expect(response).to have_http_status(:created)
+      end
+    end
+
+    context "with invalid parameters" do
+      it "does not create a new course" do
+        course_params = { course: { title: "", description: "" } }
+        expect {
+          post courses_path, params: course_params
+        }.not_to change(Course, :count)
+        expect(response).to have_http_status(:unprocessable_entity)
+      end
+    end
+  end
+
+  describe "PATCH /courses/:id" do
+    context "with valid parameters" do
+      it "updates the course" do
+        course_params = { course: { title: "Updated Title" } }
+        patch course_path(course), params: course_params
+        expect(response).to have_http_status(:ok)
+        expect(course.reload.title).to eq("Updated Title")
+      end
+    end
+
+    context "with invalid parameters" do
+      it "does not update the course" do
+        course_params = { course: { title: "" } }
+        patch course_path(course), params: course_params
+        expect(response).to have_http_status(:unprocessable_entity)
+        expect(course.reload.title).to eq("Ruby on Rails")
+      end
+    end
+  end
+
+  describe "DELETE /courses/:id" do
+    it "deletes the course" do
+      expect {
+        delete course_path(course)
+      }.to change(Course, :count).by(-1)
+      expect(response).to have_http_status(:no_content)
+    end
+  end
+end
diff --git a/spec/controllers/api/v1/institutions_controller_spec.rb b/spec/controllers/api/v1/institutions_controller_spec.rb
new file mode 100644
index 000000000..a1b11b0ae
--- /dev/null
+++ b/spec/controllers/api/v1/institutions_controller_spec.rb
@@ -0,0 +1,127 @@
+require 'rails_helper'
+
+RSpec.describe Api::V1::InstitutionsController, type: :controller do
+  let!(:institution) { create(:institution) }  
+
+  # MYSQL wait check before tests
+  before(:all) do 
+    retries = 0
+    begin
+      ActiveRecord::Base.establish_connection 
+      ActiveRecord::Base.connection.execute('SELECT 1')
+    rescue => e
+      retries += 1
+      if retries < 10
+        puts "Waiting for MySQL... Retry #{retries}/10"
+        sleep 5
+        retry 
+      else 
+        raise e
+      end 
+    end 
+  end     
+
+  
+  describe 'action_allowed?' do
+    context 'when user has Instructor role' do
+      it 'returns true' do
+        user = create(:user, :instructor)  
+        sign_in user  
+        expect(controller.send(:action_allowed?)).to eq(true)
+      end
+    end
+
+    context 'when user does not have Instructor role' do
+      it 'returns false' do
+        user = create(:user, :student)  
+        sign_in user
+        expect(controller.send(:action_allowed?)).to eq(false)
+      end
+    end
+  end
+
+  describe 'GET #index' do
+    it 'returns a successful response' do
+      get :index
+      expect(response).to have_http_status(:ok)
+      expect(json_response).to eq([institution.as_json])
+    end
+  end
+
+  describe 'GET #show' do
+    context 'when institution exists' do
+      it 'returns a successful response' do
+        get :show, params: { id: institution.id }
+        expect(response).to have_http_status(:ok)
+        expect(json_response).to eq(institution.as_json)
+      end
+    end
+
+    context 'when institution does not exist' do
+      it 'returns a not found error' do
+        get :show, params: { id: 99999 }  
+        expect(response).to have_http_status(:not_found)
+        expect(json_response['error']).to include('Institution not found')
+      end
+    end
+  end
+
+  describe 'POST #create' do
+    context 'with valid parameters' do
+      let(:valid_attributes) { { institution: { name: 'Test Institution' } } }
+
+      it 'creates a new institution and returns a created response' do
+        post :create, params: valid_attributes
+        expect(response).to have_http_status(:created)
+        expect(json_response['name']).to eq('Test Institution')
+      end
+    end
+
+    context 'with invalid parameters' do
+      let(:invalid_attributes) { { institution: { name: '' } } }
+
+      it 'does not create an institution and returns an unprocessable entity response' do
+        post :create, params: invalid_attributes
+        expect(response).to have_http_status(:unprocessable_entity)
+        expect(json_response).to include('name')
+      end
+    end
+  end
+
+  describe 'PATCH #update' do
+    context 'with valid parameters' do
+      let(:valid_attributes) { { institution: { name: 'Updated Institution' } } }
+
+      it 'updates the institution and returns a successful response' do
+        patch :update, params: { id: institution.id, institution: valid_attributes[:institution] }
+        institution.reload
+        expect(response).to have_http_status(:ok)
+        expect(institution.name).to eq('Updated Institution')
+      end
+    end
+
+    context 'with invalid parameters' do
+      let(:invalid_attributes) { { institution: { name: '' } } }
+
+      it 'does not update the institution and returns an unprocessable entity response' do
+        patch :update, params: { id: institution.id, institution: invalid_attributes[:institution] }
+        expect(response).to have_http_status(:unprocessable_entity)
+        expect(json_response).to include('name')
+      end
+    end
+  end
+
+  describe 'DELETE #destroy' do
+    it 'deletes the institution and returns a successful response' do
+      delete :destroy, params: { id: institution.id }
+      expect(response).to have_http_status(:ok)
+      expect(json_response['message']).to eq(I18n.t('institution.deleted'))
+    end
+  end
+
+  private
+
+  def json_response
+    JSON.parse(response.body)
+  end
+end
\ No newline at end of file
diff --git a/spec/controllers/api/v1/participants_controller_spec.rb b/spec/controllers/api/v1/participants_controller_spec.rb
new file mode 100644
index 000000000..feb8e0e6e
--- /dev/null
+++ b/spec/controllers/api/v1/participants_controller_spec.rb
@@ -0,0 +1,163 @@
+require 'rails_helper'
+
+RSpec.describe Api::V1::ParticipantsController, type: :controller do
+  let!(:user) { create(:user) }  
+  let!(:assignment) { create(:assignment) }  
+  let!(:participant) { create(:participant, user: user, assignment: assignment) }  
+
+    # MYSQL wait check before tests
+    before(:all) do 
+      retries = 0
+      begin
+        ActiveRecord::Base.establish_connection 
+        ActiveRecord::Base.connection.execute('SELECT 1')
+      rescue => e
+        retries += 1
+        if retries < 10
+          puts "Waiting for MySQL... Retry #{retries}/10"
+          sleep 5
+          retry 
+        else 
+          raise e
+        end 
+      end 
+    end
+
+  
+  describe 'GET #list_user_participants' do
+    context 'when user exists' do
+      it 'returns a list of participants' do
+        get :list_user_participants, params: { user_id: user.id }
+        expect(response).to have_http_status(:ok)
+        expect(json_response).to eq([participant.as_json])
+      end
+    end
+
+    context 'when user does not exist' do
+      it 'returns an error' do
+        get :list_user_participants, params: { user_id: 99999 }
+        expect(response).to have_http_status(:not_found)
+        expect(json_response['error']).to eq('User not found')
+      end
+    end
+  end
+
+  
+  describe 'GET #list_assignment_participants' do
+    context 'when assignment exists' do
+      it 'returns a list of participants' do
+        get :list_assignment_participants, params: { assignment_id: assignment.id }
+        expect(response).to have_http_status(:ok)
+        expect(json_response).to eq([participant.as_json])
+      end
+    end
+
+    context 'when assignment does not exist' do
+      it 'returns an error' do
+        get :list_assignment_participants, params: { assignment_id: 99999 }
+        expect(response).to have_http_status(:not_found)
+        expect(json_response['error']).to eq('Assignment not found')
+      end
+    end
+  end
+
+  
+  describe 'GET #show' do
+    context 'when participant exists' do
+      it 'returns the participant' do
+        get :show, params: { id: participant.id }
+        expect(response).to have_http_status(:created)  # The controller uses :created for this response
+        expect(json_response).to eq(participant.as_json)
+      end
+    end
+
+    context 'when participant does not exist' do
+      it 'returns an error' do
+        get :show, params: { id: 99999 }
+        expect(response).to have_http_status(:not_found)
+        expect(json_response['error']).to eq('Participant not found')
+      end
+    end
+  end
+
+  
+  describe 'POST #add' do
+    context 'with valid parameters' do
+      let(:valid_params) { { user_id: user.id, assignment_id: assignment.id, authorization: 'submitter' } }
+
+      it 'adds the participant and returns a successful response' do
+        post :add, params: valid_params
+        expect(response).to have_http_status(:created)
+        expect(json_response['user_id']).to eq(user.id)
+        expect(json_response['assignment_id']).to eq(assignment.id)
+      end
+    end
+
+    context 'with invalid parameters' do
+      it 'returns an error when user is not found' do
+        post :add, params: { user_id: 99999, assignment_id: assignment.id, authorization: 'submitter' }
+        expect(response).to have_http_status(:not_found)
+        expect(json_response['error']).to eq('User not found')
+      end
+
+      it 'returns an error when assignment is not found' do
+        post :add, params: { user_id: user.id, assignment_id: 99999, authorization: 'submitter' }
+        expect(response).to have_http_status(:not_found)
+        expect(json_response['error']).to eq('Assignment not found')
+      end
+
+      it 'returns an error when authorization is invalid' do
+        post :add, params: { user_id: user.id, assignment_id: assignment.id, authorization: 'invalid' }
+        expect(response).to have_http_status(:unprocessable_entity)
+        expect(json_response['error']).to eq('authorization not valid. Valid authorizations are: Reader, Reviewer, Submitter, Mentor')
+      end
+    end
+  end
+
+  
+  describe 'PATCH #update_authorization' do
+    let(:new_authorization) { 'reviewer' }
+
+    context 'with valid authorization' do
+      it 'updates the participant authorization' do
+        patch :update_authorization, params: { id: participant.id, authorization: new_authorization }
+        participant.reload
+        expect(response).to have_http_status(:created)
+        expect(participant.authorization).to eq(new_authorization)
+      end
+    end
+
+    context 'with invalid authorization' do
+      it 'returns an error' do
+        patch :update_authorization, params: { id: participant.id, authorization: 'invalid' }
+        expect(response).to have_http_status(:unprocessable_entity)
+        expect(json_response['error']).to eq('authorization not valid. Valid authorizations are: Reader, Reviewer, Submitter, Mentor')
+      end
+    end
+  end
+
+  
+  describe 'DELETE #destroy' do
+    context 'when participant exists' do
+      it 'deletes the participant and returns a success message' do
+        delete :destroy, params: { id: participant.id }
+        expect(response).to have_http_status(:ok)
+        expect(json_response['message']).to eq("Participant #{participant.id} in Assignment #{assignment.id} has been deleted successfully!")
+      end
+    end
+
+    context 'when participant does not exist' do
+      it 'returns an error' do
+        delete :destroy, params: { id: 99999 }
+        expect(response).to have_http_status(:not_found)
+        expect(json_response['error']).to eq('Not Found')
+      end
+    end
+  end
+
+  private
+
+  def json_response
+    JSON.parse(response.body)
+  end
+end
\ No newline at end of file
diff --git a/spec/controllers/api/v1/roles_controller_spec.rb b/spec/controllers/api/v1/roles_controller_spec.rb
new file mode 100644
index 000000000..d08030ae1
--- /dev/null
+++ b/spec/controllers/api/v1/roles_controller_spec.rb
@@ -0,0 +1,131 @@
+require 'rails_helper'
+
+RSpec.describe Api::V1::RolesController, type: :controller do
+  let!(:role) { create(:role) }
+  let!(:admin_user) { create(:user, role: create(:role, name: 'Administrator')) }
+  let!(:subordinate_role) { create(:role, parent: role) }
+
+    # MYSQL wait check before tests
+    before(:all) do 
+      retries = 0
+      begin
+        ActiveRecord::Base.establish_connection 
+        ActiveRecord::Base.connection.execute('SELECT 1')
+      rescue => e
+        retries += 1
+        if retries < 10
+          puts "Waiting for MySQL... Retry #{retries}/10"
+          sleep 5
+          retry 
+        else 
+          raise e
+        end 
+      end 
+    end
+
+  before do
+    sign_in admin_user
+  end
+
+  describe 'GET #index' do
+    it 'returns all roles' do
+      get :index
+      expect(response).to have_http_status(:ok)
+      expect(json_response.length).to eq(1)
+    end
+  end
+
+  describe 'GET #show' do
+    context 'when the role exists' do
+      it 'returns the role' do
+        get :show, params: { id: role.id }
+        expect(response).to have_http_status(:ok)
+        expect(json_response['name']).to eq(role.name)
+      end
+    end
+
+    context 'when the role does not exist' do
+      it 'returns an error' do
+        get :show, params: { id: 99999 }
+        expect(response).to have_http_status(:unprocessable_entity)
+        expect(json_response['error']).to eq('Parameter missing')
+      end
+    end
+  end
+
+  describe 'POST #create' do
+    context 'with valid parameters' do
+      let(:valid_params) { { role: { name: 'New Role' } } }
+
+      it 'creates a new role' do
+        post :create, params: valid_params
+        expect(response).to have_http_status(:created)
+        expect(json_response['name']).to eq('New Role')
+      end
+    end
+
+    context 'with invalid parameters' do
+      let(:invalid_params) { { role: { name: '' } } }
+
+      it 'returns an error' do
+        post :create, params: invalid_params
+        expect(response).to have_http_status(:unprocessable_entity)
+        expect(json_response['name']).to include("can't be blank")
+      end
+    end
+  end
+
+  describe 'PATCH #update' do
+    context 'with valid parameters' do
+      let(:valid_params) { { role: { name: 'Updated Role' } } }
+
+      it 'updates the role' do
+        patch :update, params: { id: role.id, role: valid_params }
+        expect(response).to have_http_status(:ok)
+        expect(json_response['name']).to eq('Updated Role')
+      end
+    end
+
+    context 'with invalid parameters' do
+      let(:invalid_params) { { role: { name: '' } } }
+
+      it 'returns an error' do
+        patch :update, params: { id: role.id, role: invalid_params }
+        expect(response).to have_http_status(:unprocessable_entity)
+        expect(json_response['name']).to include("can't be blank")
+      end
+    end
+  end
+
+  describe 'DELETE #destroy' do
+    context 'when the role exists' do
+      it 'deletes the role and returns a success message' do
+        delete :destroy, params: { id: role.id }
+        expect(response).to have_http_status(:no_content)
+        expect(json_response['message']).to eq("Role #{role.name} with id #{role.id} deleted successfully!")
+      end
+    end
+
+    context 'when the role does not exist' do
+      it 'returns an error' do
+        delete :destroy, params: { id: 99999 }
+        expect(response).to have_http_status(:unprocessable_entity)
+        expect(json_response['error']).to eq('Parameter missing')
+      end
+    end
+  end
+
+  describe 'GET #subordinate_roles' do
+    it 'returns the subordinate roles of the current user' do
+      get :subordinate_roles
+      expect(response).to have_http_status(:ok)
+      expect(json_response.length).to eq(1)
+    end
+  end
+
+  private
+
+  def json_response
+    JSON.parse(response.body)
+  end
+end
\ No newline at end of file
diff --git a/spec/controllers/api/v1/users_controller_spec.rb b/spec/controllers/api/v1/users_controller_spec.rb
new file mode 100644
index 000000000..75401087a
--- /dev/null
+++ b/spec/controllers/api/v1/users_controller_spec.rb
@@ -0,0 +1,105 @@
+require 'rails_helper'
+
+RSpec.describe Api::V1::UsersController, type: :controller do
+  let!(:user) { User.create(name: "John Doe", email: "john@example.com", password: "password123") }
+
+  # Stub authentication before each test
+  before do
+    allow(controller).to receive(:authenticate_user!).and_return(true)
+    allow(controller).to receive(:current_user).and_return(user)
+  end
+
+  describe "GET #index" do
+    it "returns a successful response" do
+      get :index
+      expect(response).to have_http_status(:ok)
+      json_response = JSON.parse(response.body)
+      expect(json_response).to be_an(Array)
+    end
+  end
+
+  describe "GET #show" do
+    context "when user exists" do
+      it "returns the user" do
+        get :show, params: { id: user.id }
+        expect(response).to have_http_status(:ok)
+        json_response = JSON.parse(response.body)
+        expect(json_response["id"]).to eq(user.id)
+        expect(json_response["name"]).to eq(user.name)
+      end
+    end
+
+    context "when user does not exist" do
+      it "returns a 404 error" do
+        get :show, params: { id: 99999 }
+        expect(response).to have_http_status(:not_found)
+        json_response = JSON.parse(response.body)
+        expect(json_response["error"]).to eq("User not found")
+      end
+    end
+  end
+
+  describe "POST #create" do
+    context "with valid parameters" do
+      it "creates a new user" do
+        expect {
+          post :create, params: { user: { name: "Alice", email: "alice@example.com", password: "password" } }
+        }.to change(User, :count).by(1)
+        expect(response).to have_http_status(:created)
+        json_response = JSON.parse(response.body)
+        expect(json_response["name"]).to eq("Alice")
+      end
+    end
+
+    context "with invalid parameters" do
+      it "returns errors" do
+        post :create, params: { user: { name: "", email: "", password: "" } }
+        expect(response).to have_http_status(:unprocessable_entity)
+        json_response = JSON.parse(response.body)
+        expect(json_response["errors"]).not_to be_empty
+      end
+    end
+  end
+
+  describe "PUT #update" do
+    context "with valid parameters" do
+      it "updates the user" do
+        put :update, params: { id: user.id, user: { name: "Updated Name" } }
+        expect(response).to have_http_status(:ok)
+        user.reload
+        expect(user.name).to eq("Updated Name")
+      end
+    end
+
+    context "with invalid parameters" do
+      it "returns errors" do
+        put :update, params: { id: user.id, user: { email: "" } }
+        expect(response).to have_http_status(:unprocessable_entity)
+        json_response = JSON.parse(response.body)
+        expect(json_response["errors"]).not_to be_empty
+      end
+    end
+  end
+
+  describe "DELETE #destroy" do
+    context "when user exists" do
+      it "deletes the user" do
+        expect {
+          delete :destroy, params: { id: user.id }
+        }.to change(User, :count).by(-1)
+        expect(response).to have_http_status(:no_content)
+      end
+    end
+
+    context "when user does not exist" do
+      it "returns 404 error" do
+        delete :destroy, params: { id: 99999 }
+        expect(response).to have_http_status(:not_found)
+        json_response = JSON.parse(response.body)
+        expect(json_response["error"]).to eq("User not found")
+      end
+    end
+  end
+end
+
+