API Testing Tool - Test APIs Online Free
Professional API testing tool for developers. Perform REST API testing with full HTTP support, authentication, and instant responses.
Master API Testing - Learn REST API Testing Like a Pro
API testing is a critical skill every developer needs. Whether you're learning what is API testing for the first time, preparing for API testing interview questions, or performing professional REST API testing in production, understanding how to validate APIs properly separates good developers from great ones. Our comprehensive API testing tool helps you practice REST assured API testing techniques and build confidence in your testing abilities.
Master different API testing tools and methodologies in one place. Learn how API testing differs from traditional testing, explore REST API testing patterns, and understand when to use different HTTP methods. From validating JSON responses to testing authentication flows, you'll gain hands-on experience with real-world API testing scenarios. Practice with our free API for testing and develop the skills that employers look for in API testing interview questions.
Understanding API Testing Fundamentals
API testing validates that your application's backend services work correctly before frontend integration. Unlike UI testing, API testing focuses on business logic, data responses, security, and performance at the service layer. This makes it faster, more reliable, and easier to automate than end-to-end testing.
Key API Testing Concepts:
REST API Testing Best Practices
Effective REST API testing follows established patterns and best practices. Learn how to structure your API testing strategy to catch bugs early, ensure reliability, and maintain code quality. These principles are frequently covered in API testing interview questions.
Essential Testing Practices:
Don't just test GET requests. Validate POST for creating resources, PUT/PATCH for updates, DELETE for removal. Each method has unique validation requirements.
Ensure 200/201 for success, 400 for bad requests, 401 for unauthorized, 404 for not found, 500 for server errors. Proper status codes are critical for API contracts.
Verify both successful authentication and rejection scenarios. Test token expiration, invalid credentials, and authorization levels. Security testing is non-negotiable.
Check response structure, data types, required fields, and business logic. Use JSON validation to ensure schema compliance.
Common API Testing Interview Questions
Preparing for interviews? These API testing interview questions come up frequently. Understanding both the concepts and practical application will help you stand out. Practice with our tool to demonstrate hands-on experience.
Q: What's the difference between SOAP and REST API testing?
REST API testing focuses on HTTP methods and stateless operations, uses JSON/XML, and is lighter weight. SOAP testing involves XML-only, strict standards, and built-in security. REST is more common in modern applications.
Q: How do you test API authentication and authorization?
Test with valid tokens to verify access, invalid tokens to ensure rejection, expired tokens for timeout handling, and different permission levels for authorization. Always test both positive and negative scenarios.
Q: What tools are used for REST API testing?
Popular REST API testing tools include Postman for Postman API testing, REST Assured for Java-based REST assured API testing, Insomnia for Insomnia API testing, SoapUI for SOAP/REST, and browser-based tools like ours for instant API testing. Each tool has strengths for different API testing scenarios and can be used for API automation testing.
Q: How do you perform REST assured API testing?
REST Assured is a Java library for API testing. It provides a DSL for HTTP requests, response validation, and JSON path extraction. Common in automated testing pipelines for continuous integration.
Professional API Testing Features
Everything you need for professional REST API testing, from basic testing to advanced REST assured API testing scenarios. Perfect for API testing interview questions preparation and real-world API testing workflows.
Essential for API testing workflows. Copy from Chrome DevToolsand paste for instant API testing setup. Perfect for reproducing API testing scenarios from production.
Manage unlimited headers for comprehensive REST API testing. Toggle headers on/off to test different API testing scenarios. Essential for CORS testing and content negotiation in API testing.
Test secured APIs with Bearer tokens and Basic auth. Critical for real-world REST API testing and REST assured API testing scenarios.
Syntax-highlighted JSON editor for request/response bodies. Essential for API testing with JSON payloads. Use our JSON beautifier for better readability.
Visual query parameter builder for REST API testing. Perfect for testing pagination, filters, and search in your API testing workflow.
Comprehensive response analysis including status codes, headers, timing, and formatted body. Essential for thorough REST API testing and debugging.
More Tools for API Testing
Enhance your API testing workflow with our data processing tools:
API Testing FAQs
What is API testing and why is it important?
API testing is the process of verifying that APIs (Application Programming Interfaces) work correctly, securely, and efficiently. It's crucial for ensuring your application's backend services function properly before they're used by frontend applications or third-party integrations.
REST API testing specifically focuses on testing RESTful web services, checking HTTP methods (GET, POST, PUT, DELETE), status codes, response times, and data validation. It's a common topic in API testing interview questions.
How do I start API testing with this tool?
Starting API testing is simple:
- Enter your API endpoint URL in the URL field
- Select HTTP method (GET, POST, PUT, DELETE) for your API testing
- Configure headers and authentication if needed for REST API testing
- Add request body for POST/PUT methods in your API testing
- Click Send to execute your API testing request
What are common API testing interview questions?
Popular API testing interview questions include:
- What is the difference between REST API testing and SOAP API testing?
- How do you perform authentication testing in REST APIs?
- What HTTP status codes should API testing validate?
- How do you test API rate limiting and performance?
- What is the difference between functional and non-functional API testing?
Can I use this as a free API for testing?
Yes! This is a completely free API testing tool with no limitations. You can use it for learning API testing, practicing REST API testing, preparing for API testing interview questions, or as a free API for testing your applications. No registration, no cost, unlimited API testing requests.
How is this different from Postman API testing?
While Postman is excellent for API testing, our tool offers instant browser-based API testing without downloads. It's perfect for quick REST API testing, sharing API testing examples, and accessing from any device. Think of it as a lightweight Postman alternative for immediate API testing needs.
What REST API testing features are included?
Our REST API testing tool includes all essential features: all HTTP methods, header management, authentication (Bearer/Basic), request body editor, response analysis, cURL import, query parameter builder, and more. Everything needed for professional REST API testing and REST assured API testing scenarios.
How do I use Postman to test API vs using this tool?
While Postman API testing requires desktop application installation, our browser-based tool lets you test API instantly. Both support similar features for API testing: HTTP methods, headers, authentication, and response viewing. Our tool is perfect for quick Postman API testing alternatives when you need immediate access without downloads or when learning how to use Postman to test API concepts.
Can I use this for API automation testing?
While this is primarily a manual API testing tool, you can use it to prototype and validate API automation testing scenarios. Test your endpoints manually first, then export requests as cURL commands for API automation testing scripts. For full API automation testing, consider REST Assured (Java), Pytest (Python), or Newman (Postman CLI) for continuous integration pipelines.