Best Free API Testing Tools

Testim is the fastest path to resilient end-to-end tests—codeless, coded or both. Testim lets you create amazingly stable codeless tests that leverage our AI, but also the flexibility to export tests as code. You can leverage Testim’s modern JavaScript API and your IDE to debug, customize or refactor tests. Store them in your version control system to keep them in sync with branches and run tests on every commit. Run parallel, cross-browser tests on our test cloud or Selenium-compatible grids while integrating with your CI and dev tools to run smoke tests on pull requests, end-to-end tests on release candidates, or full regression suites on a schedule. Customers like Microsoft, Salesforce, NetApp, Wix, and JFrog run millions of tests on Testim each month. Learn more on our website and sign up for your free account!

The collaboration platform for API development. Simplify each step of building an API and streamline collaboration so you can create better APIs—faster. Postman is a collaboration platform for API development. Postman's features simplify each step of building an API and streamline collaboration so you can create better APIs—faster. Quickly and easily send REST, SOAP, and GraphQL requests directly within Postman. Automate manual tests and integrate them into your CI/CD pipeline to ensure that any code changes won't break the API in production. Communicate the expected behavior of an API by simulating endpoints and their responses without having to set up a backend server. Generate and publish beautiful, machine-readable documentation to make your API easier to consume. Stay up-to-date on the health of your API by checking performance and response times at scheduled intervals. Provide a shared context for building and consuming APIs, and collaborate in real-time.

Tyk is a leading Open Source API Gateway and Management Platform, featuring an API gateway, analytics, developer portal and dashboard. We power billions of transactions for thousands of innovative organisations. By making our capabilities easily accessible to developers, we make it fast, simple and low-risk for big enterprises to manage their APIs, adopt microservices and adopt GraphQL. Whether self-managed, cloud or a hybrid, our unique architecture and capabilities enable large, complex, global organisations to quickly deliver highly secure, highly regulated API-first applications and products that span multiple clouds and geographies.

vStellar is a low-code, AI-powered software testing framework that simplifies automation for QA teams, developers, and enterprises. It enables effortless UI, API, and mobile testing within a unified environment, helping teams deliver accurate, consistent, and scalable results. Built for modern development pipelines, vStellar integrates seamlessly with IntelliJ IDEA, CI/CD tools, and version control systems to support end-to-end automation workflows. Its intuitive plugin and parallel testing capabilities reduce setup time while increasing efficiency across test execution. QA engineers can validate visual interfaces, endpoints, and performance metrics all within one framework. Trusted by global teams, vStellar empowers organizations to test smarter, deliver faster, and maintain the highest quality standards in every release.

Treblle is a federated API Intelligence platform built for enterprises that need full visibility, control, and security over their APIs. With a single integration, Treblle provides real-time API Discovery, Observability, Analytics, Governance, Runtime Security, and Developer Portals. It supports on-prem and private cloud deployments to meet strict compliance and data privacy requirements. Treblle helps teams shift left by surfacing API issues early in development and ensuring consistency across environments. Its AI-powered Integration Assistant simplifies onboarding and reduces manual effort. Trusted by global enterprises and recognized over 15 times by Gartner, Treblle accelerates innovation while giving you complete control over your API landscape.

Describe example API requests and responses. Define API endpoint logic in natural language. Test your API endpoints and fine-tune your prompt, response structure, and request structure. Deploy API endpoints with a single click and integrate into your applications. Build and deploy sophisticated application logic without writing any code in less than a minute. No individual LLM accounts required. Just sign up to Backengine and start building. Your endpoints run on our super fast backend architecture, available immediately. All endpoints are secure and protected so only you and your applications can use them. Easily manage your team members so everyone can work on your Backengine endpoints. Augment your Backengine endpoints with persistent data. A complete backend replacement. Use external APIs into your endpoints without doing any integration work yourself.

An all-in-one test automation solution Get started in no time, scale up with no limit, for any team, at any level. Katalon Studio Robust test generation on all platforms Productive IDE to generate automated tests easily for all platforms and OSs, regardless of application complexity. Powerful recording utility for effortlessly storing all UI elements to maximize reusability. Codeless experience for beginners. Infinite testing extension for experts. Set Up Projects Built-in project templates Start immediately with ready-made templates, test case libraries, keywords, and object repositories. All kinds of end-to-end testing in one place Uniquely perform web, mobile, API, and desktop testing – all in a single project.

At Eggplant we empower organizations to create amazing digital experiences. We help businesses to test, monitor and analyze their end-to-end customer experience and continuously improve their business outcomes. Companies worldwide use Eggplant to surpass competitors, boost productivity, and delight customers. How? By dramatically enhancing the quality, responsiveness, and performance of their software applications across different interfaces, platforms, browsers, and devices - including mobile, IoT, and desktop — in agile, DevOps, and innovative application and data environments. As software release cycles accelerate, manual testing can't keep up. AI automatically discovers user journeys, hunts for bugs and performs image-based UI tests from the user POV. Build better software with fast, broad, accurate AI-powered testing. To keep up with DevOps, continuous testing is key, streamlining development and automating the testing process.

PFLB is an AI-powered load testing platform where you can simulate massive traffic to your websites, and applications. It’s easy to use and super helpful for teams that want to ensure their product is ready to scale. Features: Realistic testing with scenario-based traffic simulation. Importing your production load profile with Google Analytics integration. Easy scripting with an intuitive no-code editor. Executing advanced JMeter scenarios at scale. Resolving bottlenecks with AI-powered performance insights. Discovering load testing results with Grafana dashboards. Protocols: HTTP, HTTPS, gRPC, JDBC, JMS, AMQP, MQTT, Kafka.

ContextQA is a groundbreaking product that empowers organizations to enhance their automation test coverage, elevate software quality, expedite product delivery, and significantly curtail expenses related to maintaining software quality through the utilization of AI-driven SaaS solutions. AI agents will transform your manual test cases and user stories into automated test cases. ContextQA collects evidence and performs root-cause analysis while reporting a bug. ContextQA identifies critical user paths and pinpoints gaps in the software testing process. Complete end-to-end testing, including contract testing, eliminates the need for separate front-end and back-end testing tools. Test and identify glitches, enhance performance, and guarantee seamless user experiences on a plethora of browsers, mobile devices, and OS. ContextQA simplifies the process of incorporating test cases with minimal effort, enabling rapid expansion of automation coverage for your products and services.