Best Free API Testing Tools

KrakenD is a high-performance API Gateway optimized for resource efficiency, capable of managing 70,000 requests per second on a single instance. The stateless architecture allows for straightforward, linear scalability, eliminating the need for complex coordination or database maintenance. It supports various protocols and API specifications, with features like fine-grained access controls, data transformation, and caching. Unique to KrakenD is its ability to aggregate multiple API responses into one, streamlining client-side operations. Security-wise, KrakenD aligns with OWASP standards and doesn't store data, making compliance simpler. It offers a declarative configuration and integrates with third-party logging and metrics tools. With transparent pricing and an open-source option, KrakenD is a comprehensive API Gateway solution for organizations prioritizing performance and scalability.

Build. Test. Automate. Empower your whole team to build and maintain automated tests, not just developers. Meet your testing demands fast. Get full test coverage in days, not months. Our natural-language tests are extremely stable to code changes. When tests break our AI will repair it in minutes. Go Agile/DevOps by setting up Continuous Testing. Push features in production the same day. Boozang supports the following test approaches: - Codeless Record/Replay interface - BDD / Cucumber - API testing - Model-based testing - HTML Canvas testing The following features makes your testing a breeze - In-browser console debugging - Screenshots to show where test fails - Integrate to any CI server - Test with unlimited parallel workers to speed up tests - Root-cause analysis reports - Trend reports to track failures and performance over time - Test management integration (Xray / Jira)

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!

Xano is the unified backend for building and deploying production-grade apps and AI agents. Instead of stitching together databases, runtimes, APIs, auth, integrations, and monitoring—plus a separate orchestrator for agents—Xano provides everything in one secure, scalable platform. Teams can model data, compose logic, expose secure APIs, and integrate with any system, while AI agents can use data and APIs, call external tools, and run server-side with observability and guardrails. Build visually, with AI, or in code from your IDE, then deploy with one click and scale automatically. Xano works with any frontend, including Lovable, Bolt, WeWeb, Retool, and custom code, so you don’t need to rebuild as you grow. Compliance, reliability, and scaling are built-in, enabling teams to focus on the business logic that makes their software unique.

Alithya GoTest is a collaborative test hub that is easy and quick to master and integrate, ensuring the quality of any professional digital solutions for companies requiring reliability without compromises. Ensure the quality of your application without sacrificing speed or agility with an easy-to-use, GUI test automation tool. Whether using scripts or not, our flexibility is unmatched, letting you create manual, automated or hybrid test suites for every desktop, web, and mobile application with ease including .Net, Java, WPF and Windows 10, modern JavaScript frameworks like React and Angular and iOS or Andoid with 2050+ browser and platform configurations. No need to jailbreak your devices. Alithya GoTest comes with a keyword library of over 1500 keywords, so you can ensure your GUI and API tests are scalable, robust, and easy to maintain. Alithya also offers consulting, coaching and training to ensure the success of your teams.

HttpMaster is a debugging and testing tool for various HTTP applications with special focus on web APIs and RESTful web services. Key features: - HttpMaster project to store complete definition of HTTP calls in one single place. - Broad set of HTTP properties (HTTP headers, URL encoding, etc.). - Dynamic parameters to simulate variations of input data or create global API values. - Response data validation with logical expressions. - Request chaining to use data from previous request with the next request. - Extensive data upload support, including 'multipart/form-data'. - Request data builder for creating request body with an optional dynamic parameters. - Request item execution with detailed progress monitoring. - Execution groups to create batches of requests. - Comprehensive execution data review and management. - Basic request tool for ad-hoc execution. - Command line interface. - PDF reports. - Support for cURL commands.

SyncTree strives to be a "Super Connecting Platform" that can easily connect any services you want. With SyncTree, which consists of SyncTree STUDIO, a solution for building backend business logic with block coding, and Block Store, a platform for buying and selling pre-made backend function blocks like App Store, you can organically utilize data and connect services to achieve unlimited service expansion. Based on aPaaS, Block Store provides APIs from various services such as ChatGPT, DALLE, YouTube, etc. in the form of 'backend function blocks', which you can subscribe to and then combine as you want quickly in SyncTree STUDIO to build your business logic. SyncTree is for everyone, whether you're an individual or a business, and you can subscribe and use it according to your needs, from the free version to the PRO version.

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.