API Documentation Using Swagger/OpenAPI

I need a developer to create comprehensive API documentation for an existing backend application using Swagger/OpenAPI. Scope of Work * Analyze existing REST API endpoints * Document all routes, parameters, request bodies, and responses * Define authentication methods (JWT, API Key, OAuth, etc.) * Add endpoint descriptions and usage examples * Document error responses and status codes * Generate interactive Swagger UI documentation * Ensure documentation is easy for frontend developers and third-party integrators to use Deliverables * Complete OpenAPI 3.0 specification * Interactive Swagger UI documentation * API examples for all endpoints * Documentation for authentication and authorization * README with setup instructions Preferred Tech Stack * Node.js * Express.js or NestJS * TypeScript * Swagger/OpenAPI 3.0 * Swagger UI Express * Postman (optional for testing) Example Endpoints to Document * Authentication (Register/Login) * User Management * CRUD Operations * File Uploads * Payment Endpoints * Notification Services Expected Outcome A fully documented API that allows developers to understand, test, and integrate with the backend quickly using Swagger UI.