API Request Builder

Construct and send HTTP requests to any API endpoint. View responses, headers, and status codes in real-time.

Query parameters to be added to the URL.

Custom HTTP headers for the request.

Response

How to Use the API Request Builder

  1. Enter URL & Method: Select the HTTP method (GET, POST, etc.) and enter the full request URL.
  2. Configure Request (Optional):
    • Params: Add URL query parameters (key-value pairs).
    • Authorization: Select an auth type (e.g., Bearer Token, Basic Auth) and provide credentials.
    • Headers: Add any custom HTTP headers required by the API.
    • Body: For methods like POST or PUT, select the body type (form-data, x-www-form-urlencoded, raw) and input your data. For 'raw', you can specify content types like JSON, XML, etc.
  3. Send Request: Click the "Send" button.
  4. View Response: The response section will show the status code, time taken, and size. You can view the response Body (formatted if possible), Headers, and the Raw response.

Note on CORS: Requests are made from your browser. If the target API doesn't have Cross-Origin Resource Sharing (CORS) headers allowing requests from this domain, the request might be blocked by your browser. For testing such APIs, consider using a browser extension that can modify CORS headers (for development/testing only) or a server-side proxy.

About API Request Builder

What does this tool do?

Our API Request Builder provides a complete HTTP client interface for testing REST APIs directly in your browser. It supports all major HTTP methods, custom headers, authentication schemes, various body formats, and provides detailed response analysis with syntax highlighting.

Why is this useful?

Testing APIs before integration saves development time and prevents errors. Our tool eliminates the need for command-line tools or separate applications, providing immediate API testing with a user-friendly interface that works entirely in your browser.

Who uses this tool?

  • API developers - Test endpoints during development and debug API responses
  • Frontend developers - Verify API contracts before implementing client-side integration
  • QA engineers - Validate API functionality and test edge cases
  • System integrators - Test third-party APIs and validate data formats
  • DevOps teams - Monitor API health and troubleshoot connectivity issues

How to test APIs

  1. Select the appropriate HTTP method (GET, POST, PUT, DELETE, etc.)
  2. Enter the complete API endpoint URL including protocol (https://)
  3. Add query parameters in the Params tab for GET requests or URL modifications
  4. Configure authentication using Bearer tokens, Basic auth, or custom headers
  5. Set request headers including Content-Type, Accept, or custom API headers
  6. For POST/PUT requests, configure the request body using form-data, URL-encoded, or raw JSON/XML
  7. Click Send to execute the request and analyze the response

Example

Testing a REST API: POST to https://api.example.com/users with JSON body {"name": "John", "email": "john@example.com"} using Bearer token authentication returns 201 status with the created user object including assigned ID.

Understanding API responses

Status Code
HTTP status indicating success (200-299), client error (400-499), or server error (500-599). Essential for determining request outcome.
Response Time
Round-trip time in milliseconds from request to response. Important for performance analysis and API optimization.
Response Size
Total bytes received including headers and body. Useful for monitoring data usage and response efficiency.
Response Body
Actual data returned by the API, automatically formatted as JSON, XML, or plain text based on content type.
Response Headers
Server-provided metadata including content type, caching directives, security headers, and custom API information.

Successful API testing indicators

  • 2xx status codes: Request processed successfully by the server
  • Expected response format: JSON/XML structure matches API documentation
  • Reasonable response time: Usually under 1-2 seconds for good user experience
  • Proper headers: Content-Type matches actual response format

Common API testing issues

  • CORS errors: Browser blocks requests to different domains without proper headers
  • Authentication failures: 401/403 status codes indicate invalid or missing credentials
  • Validation errors: 400 status with error details about malformed requests
  • Rate limiting: 429 status when too many requests are sent too quickly

HTTP method guidelines

  • GET: Retrieve data, should not modify server state, supports query parameters
  • POST: Create new resources, send data in request body
  • PUT: Update/replace entire resources, idempotent operation
  • PATCH: Partial updates to resources, send only changed fields
  • DELETE: Remove resources, usually returns confirmation or empty response

Common use cases

API Development Testing

Test endpoints during development, verify request/response formats, and debug API logic before deploying to production environments.

Third-Party Integration

Explore external API capabilities, understand authentication requirements, and test data formats before implementing integrations.

Debugging Production Issues

Reproduce API errors, test different request parameters, and analyze response data to identify and resolve integration problems.

API Documentation Validation

Verify that API behavior matches documentation, test example requests, and ensure consistent response formats across endpoints.

Authentication best practices

Always use HTTPS for production API testing, store API keys securely, and use environment-specific credentials. Bearer tokens should be treated as passwords and never shared publicly.

CORS and browser limitations

Modern browsers enforce CORS policies that may block API requests to different domains. For development testing, consider using CORS browser extensions or server-side proxies to bypass these restrictions.

Related tools