Best Practices for REST APIs

Key Guidelines for Building Reliable and Efficient RESTful Services

Understanding and applying best practices in the design and development of RESTful APIs can make a world of difference in their usability and maintenance. This post covers the essential best practices to API development with practical examples and code snippets to guide you through key concepts.

Introduction to REST APIs

• REST (Representational State Transfer) APIs are the most common and popular architectural style for designing APIs

• They use HTTP methods such as GET, POST, PUT, DELETE to perform CRUD (Create, Read, Update, Delete) operations on resources

1. Use Nouns for Resource URIs

• RESTful URIs should represent resources, not actions

• Use nouns instead of verbs to define your endpoints

• This makes your API more intuitive and aligned with REST principles

Bad:

GET /getAllUsers 
POST /createNewUser

Good:

GET /users 
POST /users

2. Use HTTP Methods Correctly

HTTP methods should correspond to CRUD operations

• GET: Retrieve a resource or collection

• POST: Create a new resource

• PUT: Update an existing resource (whole resource)

• PATCH: Update a resource (partial update)

• DELETE: Delete a resource

Example

POST /users         // Create a new user
GET /users/:id      // Retrieve user with ID
PUT /users/:id      // Update user with ID
DELETE /users/:id   // Delete user with ID

3. Use Proper Status Codes

HTTP status codes communicate the outcome of an API request

Use them to indicate success, error, or specific conditions:

• 2xx: Success (e.g., 200 OK, 201 Created)

• 3xx: Redirection (e.g., 301 Moved Permanently)

• 4xx: Client Error (e.g., 400 Bad Request, 404 Not Found)

• 5xx: Server Error (e.g., 500 Internal Server Error)

Example:

GET /users/123

200 OK
Content-Type: application/json

{
    "id": 123,
    "name": "John Doe",
    "email": "john.doe@example.com"
}

4. Version Your APIs

• Versioning helps manage changes and backward compatibility

• Include the version number in the URI path or headers

Example:

GET /v1/users

5. Handle Errors Gracefully

• Provide meaningful error messages and use appropriate HTTP status codes for errors - include error details in the response payload, so either a developer can troubleshoot it or a client can uniquely identify an error type and come up with a strategy for presenting this information to an end-user

Example:

GET /users/999

404 Not Found
Content-Type: application/json

{
    "error": "User not found"
}

6. Implement Pagination for Large Collections

• When returning large datasets, use pagination to limit results returned by a single GET endpoint

• This dramatically improve performance, but, more importantly, it is a better design implementation, both at the back-end and front-end

• The client would likely feature lazy loading or pagination buttons to navigate forwards and backwards through more data retrieval, which would trigger the API to go and retrieve the subsequent/previous page

• At the API level, we also send back the page number, number of pages and often a URI to the previous and next endpoints to allow client apps to swiftly navigate through the backend data in a simple manner

Example:

GET /users?page=2&limit=10

7. Secure Your API

• Use HTTPS to encrypt data transmitted between clients and servers

• Implement authentication (e.g., OAuth, JWT) and authorization mechanisms to protect resources - and prevent your API from being exposed publicly

Authentication:

Authorization:

8. Document Your API

• Clear documentation helps developers understand and use your API effectively

• Use tools like Swagger, OpenAPI or Postman to generate API documentation

• Postman also comes with the ability to embed your API endpoint testing and documentation in a centralized place

9. Use Consistent Naming Conventions

• Follow naming conventions for endpoints, parameters, and response formats

• Use camelCase, snake_case, or kebab-case consistently

• The use of one of the naming conventions above often depends on the language / framework that you are using, since often languages come with style conventions for how to structure the code

  • For example, snake_case is more common in Python whereas camelCase is more common in Javascript/Node

10. Test Your API Thoroughly

• Write unit tests, integration tests, and end-to-end tests to validate your API's functionality, performance, and security

• As your application grows, implement a CI/CD pipeline and a test-driven development approach, allowing developers to implement new features faster by running every new implementation through an automated testing and deployment pipeline of scripts and programs