Backend Developer Needed to Complete Social, Credit Transfer and Event API Endpoints

Backend Developer Needed to Complete Social, Credit Transfer and Event API Endpoints We are looking for an experienced backend developer to complete and connect several existing API endpoints for our mobile applications and administration dashboard. The endpoint structures have already been created. The developer’s responsibility will be to connect them properly to our backend, database and existing user authentication system, ensuring that the complete functionality works correctly. Scope of work 1. Friends and associates list Complete an endpoint that returns a user’s friends and associates. The mobile applications will call this endpoint when the user opens their Friends and Associates section. The response should provide the information required to display both lists. The administration dashboard must also be able to retrieve and display the friends and associates connected to a particular user. 2. Send a friend request Complete an endpoint that allows one authenticated user to send a friend request to another user. The endpoint should: * Identify the authenticated sender. * Accept the receiving user’s ID. * Prevent users from sending requests to themselves. * Prevent duplicate requests. * Prevent new requests where the two users are already friends. * Store the request with the appropriate pending status. 3. Accept a friend request Complete an endpoint that allows the receiving user to accept a pending friend request. Once accepted: * The users should become friends. * The relationship should appear in both users’ friend lists. * The original request should be marked as accepted. * Only the intended recipient should be allowed to accept the request. 4. Remove a friend Complete an endpoint that allows a user to remove an existing friend. Once the relationship is removed, neither person should appear as a friend of the other. The developer should ensure that this does not accidentally delete either user’s account or unrelated records. 5. Send credit to another user Complete an endpoint that allows an authenticated user to transfer account credit to another user. The request will include: * The receiving user’s ID * The amount to be transferred The backend should: * Confirm that both users exist. * Validate the transfer amount. * Confirm that the sender has sufficient available credit. * Deduct the amount from the sender. * Add the same amount to the recipient. * Record the transaction for both users. * Prevent duplicate transfers if the same request is submitted more than once. * Complete the debit, credit and transaction records as one atomic database operation. * Return a clear success or failure response. This endpoint involves user balances, so security, transaction accuracy and protection against duplicate processing are essential. 6. Send app events to the backend Complete an endpoint that allows the mobile applications to send events to our system. The endpoint should receive the event information from an authenticated user, validate the supplied data and store or process the event through our existing backend system. The final event request fields and supported event types will be confirmed before implementation. General requirements The developer must: * Work with our existing backend architecture and database. * Connect the existing endpoint structures rather than unnecessarily rebuilding them. * Follow the project’s current coding conventions. * Use the authenticated user’s identity where appropriate instead of trusting a sender ID supplied by the mobile application. * Add proper validation and authorisation. * Return consistent success and error responses. * Prevent duplicate friend requests and duplicate credit transfers. * Handle missing users, invalid requests and database errors safely. * Add appropriate logging without exposing sensitive user or financial information. * Test every endpoint thoroughly. * Provide API documentation and request-and-response examples. * Provide the information needed by our iOS, Android and administration-dashboard developers to integrate the endpoints. Required experience We are looking for someone with experience in: * Backend API development * REST APIs * Node.js and our existing backend framework * Database relationships and queries * Authentication and authorisation * Financial or wallet transaction handling * Atomic database transactions * API validation and error handling * Testing and documenting endpoints * Supporting mobile-app API integrations Deliverables * All required endpoints connected to the backend and database * Friends and associates list functionality * Friend-request, acceptance and removal functionality * User-to-user credit transfers * App event submission functionality * Administration-dashboard access to users’ friends and associates * Validation, authorisation and error handling * Automated tests covering successful and unsuccessful scenarios * API documentation with example requests and responses * Code submitted through our existing development and review process When applying, please provide: * Examples of similar backend API work * Your experience with social relationships or friend-request systems * Your experience with wallet, credit or balance-transfer systems * Your estimated completion time * Your fixed price or hourly rate