REST API Development Company in India

REST APIs and GraphQL solve the same problem - data exchange between systems - but with fundamentally different approaches. REST APIs expose multiple fixed endpoints, each returning a predefined data structure. A request to GET /users returns all user fields the server has defined, whether the client needs them all or not. GraphQL exposes a single endpoint where the client specifies exactly which fields to return in a query. If you need a user's name and email but not their address, you ask for just those fields and receive just those fields. REST is simpler, benefits from HTTP caching, and is the right choice for public APIs, simple CRUD operations, and standard integrations. GraphQL eliminates over-fetching (receiving too much data) and under-fetching (needing multiple requests to get complete data) - making it ideal for mobile applications where bandwidth matters, complex data with many relationships, and front-end teams who want precise control over data fetching without backend changes.

A REST API call is pull-based - your application makes a request to an external system to check if something changed, and receives a response. A webhook is push-based - the external system automatically sends an HTTP POST request to your application the moment a relevant event occurs, without you having to ask. The practical difference: to check if a payment succeeded using polling, you would call GET /payments/123 every 5 seconds until the status changed - consuming resources and adding latency. With a webhook, Stripe sends a payment.succeeded event to your server URL the instant the payment completes - zero latency, zero wasted requests. Webhooks are essential for real-time integrations with payment processors (Stripe, Razorpay), source control platforms (GitHub, GitLab), e-commerce platforms (Shopify), and communication tools (Twilio). Reliable webhook consumers require idempotency keys (prevent duplicate processing on retry), signature verification (authenticate the sender), and dead-letter queues (capture events that failed processing).

API authentication is the process of verifying the identity of a client making an API request, ensuring only authorized consumers can access your API. There are three main authentication methods: (1) API Keys - a simple static token passed in a header or query parameter. Easy to implement but difficult to manage at scale, cannot expire automatically, and provide no user-level identity. Best for server-to-server integrations where the consuming service is known and trusted. (2) JWT (JSON Web Tokens) - a signed, encoded token containing user identity claims and an expiry time. The server generates a JWT on login; the client sends it in every request header. The server validates the signature and checks expiry without a database query. Best for user authentication in web and mobile applications. (3) OAuth 2.0 - a delegated authorization framework where users grant your application permission to access their data on another platform (Google, Facebook, GitHub) without sharing their password. Best for social login, third-party API access, and public APIs where third-party developers build integrations.

OpenAPI (formerly Swagger) is the industry-standard specification for describing REST APIs in a machine-readable YAML or JSON file. An OpenAPI specification documents every API endpoint - its URL, HTTP method, path and query parameters, request body schema with field types and validation rules, response schemas for every status code, authentication methods, and example values. This specification serves three critical purposes: (1) Interactive documentation - tools like Swagger UI and Redoc render the specification as a live documentation website where developers can read API documentation and test endpoints in a browser without writing code. (2) SDK generation - tools like OpenAPI Generator can automatically create client libraries in any programming language from the specification. (3) Contract testing - the specification is a contract between backend and frontend teams. Frontend developers can build against the specification before the backend is finished. All APIs at Evolution Infosystem are developed with OpenAPI 3.1 specification-first, meaning the specification is written and approved before implementation begins.

API versioning is the practice of maintaining multiple versions of an API simultaneously so that changes to the API do not break existing integrations. When you release a new version of an API with breaking changes - removing a field, changing a field's data type, or changing a URL structure - clients using the old version continue to work undisturbed while new clients adopt the new version. There are three common versioning strategies: (1) URL path versioning - /v1/users, /v2/users - the most explicit and widely understood approach, easy to document and test separately. (2) Request header versioning - API-Version: 2 in the request header - cleaner URLs but harder to test in a browser. (3) Query parameter versioning - /users?version=2 - the least recommended as query parameters are typically for filtering, not versioning. We recommend URL path versioning as the default for public APIs. We also recommend maintaining a clear deprecation policy - announcing deprecated versions with a minimum 6-month sunset timeline and communicating via email and API response headers (Deprecation and Sunset headers per RFC 8594).

The most important REST API best practices are: (1) Use nouns not verbs in URLs - /orders not /getOrders. (2) Use proper HTTP methods - GET for read, POST for create, PUT/PATCH for update, DELETE for remove. (3) Return appropriate HTTP status codes - 200 OK, 201 Created, 400 Bad Request, 401 Unauthorized, 403 Forbidden, 404 Not Found, 409 Conflict, 422 Unprocessable Entity, 429 Too Many Requests, 500 Internal Server Error. (4) Implement pagination for list endpoints - cursor-based pagination scales better than offset for large datasets. (5) Version your API from day one - /v1/ prefix before you have breaking changes, not after. (6) Document with OpenAPI before you implement. (7) Implement rate limiting on all endpoints. (8) Validate all inputs against schema. (9) Return meaningful error messages with a consistent error format. (10) Never return 200 OK with an error in the response body - this makes client error handling impossible.

API development timeline depends on scope and complexity. A simple CRUD REST API with 5-10 endpoints, basic authentication, and database integration takes 2-4 weeks. A medium-complexity API with 20-40 endpoints, OAuth 2.0 authentication, multiple resource types, and 2-3 third-party integrations takes 4-8 weeks. A complex enterprise API platform with 50+ endpoints, multiple authentication mechanisms, GraphQL layer, webhook system, and 5+ third-party integrations takes 2-4 months. API documentation and security audit add 1-2 weeks to any project. At Evolution Infosystem, we develop APIs in 2-week Agile sprints, delivering working endpoints on a staging environment at the end of every sprint - integrating teams have access to real endpoints throughout the project, not just at the end.

REST API design and development, GraphQL API development, third-party API integration, webhook development, microservices architecture, OpenAPI documentation, API security audit, and legacy API modernisation.

Node.js with Fastify and Express, Python with FastAPI and Django REST Framework, Go with Gin, and .NET Core with ASP.NET Web API - selected based on performance requirements and team expertise.

Yes. Evolution Infosystem addresses all 10 items from OWASP's API Security Top 10 on every production API project, and provides written security audit reports as part of the pre-production quality process.

Stripe, Razorpay, PayPal, Paytm, CCAvenue, PayU, and UPI payment integrations with idempotent charge creation, webhook consumers for all payment events, and reconciliation automation.

Yes. All API projects at Evolution Infosystem use OpenAPI 3.1 specification-first design - the specification is written and approved before implementation, then used to generate Swagger UI or Redoc developer documentation.