REST API Methods Explained with Best Practices for Building Clean and Secure APIs

APIs power the modern web. From mobile apps to single-page applications, almost every software today depends on APIs to communicate and exchange data. Among them, REST APIs are the most widely used because of their simplicity and compatibility with HTTP.

In this article, we will take a clear and simple look at REST API methods and discuss best practices that help you build clean, secure, and scalable APIs.

Let’s get started.

What is a REST API?

REST (Representational State Transfer) is a set of rules and principles for designing networked applications. REST APIs work over HTTP and use standard HTTP methods to perform actions on resources. In simple terms, a REST API allows different systems to communicate over the web using URLs, HTTP methods, and JSON for exchanging data.

If you have built or consumed a web application, you are likely already using REST APIs without realizing it.

HTTP Methods — The Heart of REST APIs

HTTP methods define what action you want to perform on a resource. Let’s go through each of them.

GET — Retrieve Data

GET is used to fetch data from the server. It does not change anything on the server. It is read-only and safe.

Example:

GET /api/v1/users

This will return the list of users.

When to use:

• Fetch lists
• Fetch individual records
• Any read-only operation

POST — Create New Resource

POST is used to create a new resource. The data you send in the request body is used to create something new on the server.

Example:

POST /api/v1/users

Request body:

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

This will create a new user.

When to use:

• Creating new records
• Submitting forms or data that create something new

PUT — Replace Resource

PUT is used to replace the entire resource with new data. However, in many real-world APIs, PUT may also be used to partially update data, similar to PATCH. Still, the original intention of PUT is to replace the full resource.

Example:

PUT /api/v1/users/123

Request body:

{
  "name": "Updated Name",
  "email": "updated@example.com"
}

This will replace the user with ID 123 with the new data.

When to use:

• Replace full resource
• Update all fields of a resource
• Sometimes used for partial updates (depends on API design)

PATCH — Partial Update

PATCH is used to update only specific fields in a resource. It does not replace the entire resource.

Example:

PATCH /api/v1/users/123

Request body:

{
  "email": "newemail@example.com"
}

This will only update the email of user 123.

When to use:

• Update one or more fields
• When full replacement is not required

PATCH requests are usually not idempotent by default. Whether they are or not depends on how you design the API.

DELETE — Remove Resource

DELETE is used to remove a resource from the server.

Example:

DELETE /api/v1/users/123

This will delete the user with ID 123.

When to use:

• Removing records
• Canceling or deleting resources

Idempotency — Why It Matters

Idempotency means performing the same operation multiple times will produce the same result.

• GET, PUT, and DELETE should be idempotent.
• POST is not idempotent. Calling POST twice may create duplicate records.
• PATCH may or may not be idempotent depending on implementation.

Idempotency makes your API predictable and reliable, especially when dealing with network retries.

Best Practices for Building REST APIs

Using correct HTTP methods is just the start. To make your API clean and easy to use, you should also follow these best practices.

Use Clean and Consistent URLs

Keep your API URLs meaningful and resource-oriented.

Good example:

/api/v1/users
/api/v1/users/123

Avoid:

/api/v1/doAction
/api/v1/getUserData

Do not use verbs in URLs. HTTP methods already indicate the action.

Version Your API

Always version your API, especially if it is public or shared with other developers.

Example:

/api/v1/users

Versioning allows you to make changes later without breaking old clients.

Use Correct HTTP Status Codes

Return proper status codes to indicate the result of the request.

• 200 OK: Success
• 201 Created: Resource created
• 204 No Content: Successful but no content
• 400 Bad Request: Invalid input
• 401 Unauthorized: Authentication required
• 403 Forbidden: No permission
• 404 Not Found: Resource missing
• 422 Unprocessable Entity: Validation failed
• 500 Internal Server Error: Server issue

These codes help API consumers handle responses correctly.

Return Consistent JSON Responses

Your API responses should follow a predictable structure.

Example for success:

{
  "status": "success",
  "data": { }
}

Example for errors:

{
  "status": "error",
  "message": "Email is required."
}

This makes parsing and debugging easy for developers.

Validate and Sanitize Inputs

Never trust incoming data. Always validate and sanitize inputs to:

• Prevent SQL Injection
• Avoid Cross-Site Scripting (XSS)
• Ensure data integrity

Reject requests with invalid or missing data.

Authentication and Authorization

Protect sensitive endpoints.

• Use JWT, OAuth, or API keys for authentication.
• Check user permissions before processing requests.

Unprotected APIs are a security risk.

Pagination, Filtering, and Sorting

Do not return huge lists in a single response. Use pagination.

Example:

/api/v1/users?page=2&per_page=20

Also allow filtering and sorting for flexible data fetching.

Rate Limiting and Throttling

Prevent abuse and DDoS attacks by limiting the number of requests.

Rate limiting can be implemented at the API gateway, load balancer, or server level.

If limit is exceeded, return:

429 Too Many Requests

Rate limiting keeps your API healthy and available.

Proper Error Handling

Always send clear and helpful error messages.

Avoid this:

{ "error": "Something went wrong" }

Instead, send this:

{
  "status": "error",
  "message": "Invalid user ID"
}

Good error messages save developers hours of debugging.

Caching Strategies

Implement caching to improve performance.

• Use ETag or Last-Modified for conditional requests.
• Use Cache-Control headers to allow clients to cache data.

Caching reduces server load and improves speed.

Secure Sensitive Data

• Use HTTPS.
• Never expose passwords, tokens, or internal fields.
• Log sensitive data only if necessary.

Security should never be compromised.

Cross-Origin Resource Sharing (CORS)

APIs consumed by browsers must handle CORS properly.

• Set Access-Control-Allow-Origin header.
• Avoid using * (wildcard) unless absolutely necessary. Allow only trusted domains for authenticated endpoints.

Proper CORS configuration ensures secure cross-domain communication.

Logging and Monitoring

Always log:

• Requests and responses (without sensitive data)
• Errors and exceptions

Logs help in debugging and improve reliability.

Documentation and Developer Experience

Good APIs are easy to use. Document your API properly.

• Describe all endpoints
• Show request and response examples
• List error codes
• Use tools like Swagger etc

Documentation reduces support requests and makes onboarding easier.

Deprecation and Versioning Strategy

Do not break old APIs suddenly.

• Mark endpoints as deprecated.
• Allow clients time to migrate.
• Introduce changes in new versions.

Smooth transitions make your API reliable for long-term use.

Conclusion

REST APIs are simple but powerful. When designed properly, they make your application easy to integrate and extend. Understanding the correct usage of HTTP methods and following best practices ensures that your API is secure, reliable, and developer-friendly.

Whether you are building a public API or an internal service, applying these principles from the start will save you time and trouble in the future. A well-designed API is not only easy to use but also easy to maintain and scale.

If you are building your next API, make sure to use these guidelines as your checklist. It will make a huge difference in the quality of your project.