API Tester

How to Use the API Tester

1. Select Method: Choose the HTTP method (GET, POST, PUT, DELETE, etc.)
2. Enter URL: Input the API endpoint URL you want to test
3. Add Headers: Include any required headers like Authorization or Content-Type
4. Add Request Body: For POST/PUT requests, include the request payload
5. Send Request: Click Send to execute the API call
6. View Response: Analyze the response body, headers, and status code

HTTP Methods Explained

GET

Used to retrieve data from a server. GET requests should not modify server state and are considered safe and idempotent. No request body is typically included.

POST

Used to create new resources on the server. POST requests often include data in the request body and can modify server state. Not idempotent by default.

PUT

Used to update or create resources. PUT requests should be idempotent, meaning multiple identical requests should have the same effect as a single request.

DELETE

Used to remove resources from the server. DELETE requests should be idempotent and typically don't include a request body.

PATCH

Used to partially update resources. PATCH requests contain data describing changes to be made to the resource.

Common HTTP Headers

Authorization

• Bearer Token: Authorization: Bearer your-jwt-token
• Basic Auth: Authorization: Basic base64-encoded-credentials
• API Key: Authorization: ApiKey your-api-key

Content-Type

• JSON: Content-Type: application/json
• Form Data: Content-Type: application/x-www-form-urlencoded
• XML: Content-Type: application/xml
• Plain Text: Content-Type: text/plain

Accept

• JSON: Accept: application/json
• XML: Accept: application/xml
• Any: Accept: */*

HTTP Status Codes

2xx Success

• 200 OK: Request successful
• 201 Created: Resource created successfully
• 204 No Content: Request successful, no response body

3xx Redirection

• 301 Moved Permanently: Resource permanently moved
• 302 Found: Resource temporarily moved
• 304 Not Modified: Resource not modified since last request

4xx Client Errors

• 400 Bad Request: Invalid request format
• 401 Unauthorized: Authentication required
• 403 Forbidden: Access denied
• 404 Not Found: Resource not found
• 429 Too Many Requests: Rate limit exceeded

5xx Server Errors

• 500 Internal Server Error: Generic server error
• 502 Bad Gateway: Invalid response from upstream server
• 503 Service Unavailable: Server temporarily unavailable

API Testing Best Practices

Request Structure

• Use appropriate HTTP methods for each operation
• Include proper Content-Type headers when sending data
• Format JSON request bodies correctly
• Use meaningful parameter names and values

Authentication

• Never expose API keys in URLs or logs
• Use HTTPS for all authenticated requests
• Implement proper token refresh mechanisms
• Test authentication failure scenarios

Error Handling

• Test various error conditions (4xx, 5xx responses)
• Verify error messages are helpful and consistent
• Check that sensitive information isn't leaked in errors
• Test rate limiting and timeout scenarios

Common API Testing Scenarios

CRUD Operations

• Create: POST /api/users with user data
• Read: GET /api/users/123 to fetch user
• Update: PUT /api/users/123 with updated data
• Delete: DELETE /api/users/123 to remove user

Authentication Flow

• POST /api/auth/login with credentials
• Receive authentication token
• Use token in Authorization header for subsequent requests
• Test token expiration and refresh

Data Validation

• Test with valid data formats
• Test with invalid data to trigger validation errors
• Test boundary conditions (max lengths, limits)
• Test special characters and encoding issues

Frequently Asked Questions

Is the API Tester secure for testing production APIs?

The API Tester runs entirely in your browser and doesn't store or log your requests. However, for sensitive production APIs, consider using this tool only for read-only operations or in development/staging environments.

Can I test APIs that require authentication?

Yes, you can add authentication headers like Authorization tokens, API keys, or basic authentication credentials. The tool supports all common authentication methods.

What if my API requires CORS headers?

CORS (Cross-Origin Resource Sharing) restrictions may prevent browser-based tools from accessing certain APIs. If you encounter CORS errors, the API server needs to be configured to allow browser requests from this domain.

Can I save and reuse API requests?

Currently, the tool doesn't save requests between sessions. For persistent request collections, consider using dedicated API testing tools like Postman or Insomnia for your development workflow.

How do I test APIs with file uploads?

This tool currently supports text-based request bodies. For file uploads requiring multipart/form-data, you'll need to use specialized tools or encode files as base64 strings in your request body.

What's the maximum request/response size supported?

The tool can handle reasonably large requests and responses, but very large payloads (several MB) may cause performance issues in the browser. For testing large data transfers, consider using command-line tools or dedicated API clients.