Best Free API Testing Tools of 2025

Engineered for peak performance and efficient resource use, KrakenD can manage a staggering 70k requests per second on just one instance. Its stateless build ensures hassle-free scalability, sidelining complications like database upkeep or node synchronization. In terms of features, KrakenD is a jack-of-all-trades. It accommodates multiple protocols and API standards, offering granular access control, data shaping, and caching capabilities. A standout feature is its Backend For Frontend pattern, which consolidates various API calls into a single response, simplifying client interactions. On the security front, KrakenD is OWASP-compliant and data-agnostic, streamlining regulatory adherence. Operational ease comes via its declarative setup and robust third-party tool integration. With its open-source community edition and transparent pricing model, KrakenD is the go-to API Gateway for organizations that refuse to compromise on performance or scalability.

Postman serves as a collaborative platform for developing APIs, designed to simplify the entire process of API creation and enhance teamwork, enabling the rapid development of superior APIs. The platform's features facilitate each phase of API construction, making it easier to collaborate and accelerate the creation of high-quality APIs. Users can quickly and effortlessly send requests for REST, SOAP, and GraphQL directly within Postman, optimizing their workflow. Additionally, it allows for the automation of manual tests, seamlessly integrating them into your CI/CD pipeline to safeguard against potential issues when code changes are deployed to production. API behavior can be communicated effectively by simulating endpoints and their respective responses without the need for a backend server setup. You can also generate and publish visually appealing, machine-readable documentation, which helps in making your API more accessible for users. Regular performance and response time checks ensure you stay informed about your API's health, allowing for proactive management. Lastly, Postman fosters a shared environment for API creation and consumption, enabling real-time collaboration among team members. Postman’s AI Agent Builder revolutionizes the development of AI agents with its no-code platform, enabling users to build, test, and deploy powerful agents without coding expertise. It provides access to a vast library of over 100,000 APIs and a variety of LLMs, offering tools to compare their performance, cost, and response quality. The visual workflow builder simplifies creating multi-step agent interactions, and its testing tools ensure reliability before deployment.

Tyk is an Open Source API Gateway and Management Platform that is leading in Open Source API Gateways and Management. It features an API gateway, analytics portal, dashboard, and a developer portal. Supporting REST, GraphQL, TCP and gRPC protocols We facilitate billions of transactions for thousands of innovative organisations. Tyk can be installed on-premises (Self-managed), Hybrid or fully SaaS.

Xano offers a fully-managed, scaleable infrastructure that powers your backend. You can also quickly create the business logic that powers your backend with Xano without writing a single line or use one our pre-made templates to launch quickly and without compromising security or scale. You can quickly create custom API endpoints with just one line of code. Our out-of-the box CRUD operations, Marketplace extensions and templates will accelerate your time to market. Your API is "ready-to use" so you can connect to any frontend immediately and concentrate on your business logic. Swagger automatically documents everything so that you can connect to any frontend easily. Xano uses PostgreSQL, which offers the flexibility of a relational and the Big data needs that a NoSQL solution. You can add features to your backend with just a few clicks. Or, you can use pre-made templates and extensions to jumpstart the project.

Ambassador Edge Stack, a Kubernetes-native API Gateway, provides simplicity, security, and scalability for some of the largest Kubernetes infrastructures in the world. Ambassador Edge Stack makes it easy to secure microservices with a complete set of security functionality including automatic TLS, authentication and rate limiting. WAF integration is also available. Fine-grained access control is also possible. The API Gateway is a Kubernetes-based ingress controller that supports a wide range of protocols, including gRPC, gRPC Web, TLS termination, and traffic management controls to ensure resource availability.

Apidog offers a comprehensive suite of tools designed to streamline the entire API lifecycle, enabling research and development teams to adopt optimal practices for API development focused on design. With a robust visual editor, users can both design and debug their APIs effectively. The platform enhances usability with JSON Schema support, simplifying the process of describing and debugging. Apidog also automates various aspects of the API lifecycle, including test generation based on API specifications, visual assertions, built-in response validation, and integration with continuous integration/continuous deployment (CI/CD) pipelines. Additionally, it facilitates the creation of visually engaging API documentation that can be published to a custom domain or shared securely among collaborative teams. Its local and cloud mock engine produces realistic mock data that aligns with field names and specifications, eliminating the need for script writing. High-quality tools empower your entire team to work cohesively while minimizing redundant tasks. Seamlessly describe your API during testing, and with just a click, generate JSON or XML schemas. You can also easily create test cases from APIs, visually add assertions, and develop intricate test scenarios that incorporate branches and iterations. By leveraging Apidog, teams can not only enhance their efficiency but also foster better collaboration throughout the development process.

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.

You can use your favorite debugging software to locally troubleshoot your Kubernetes services. Telepresence, an open-source tool, allows you to run one service locally and connect it to a remote Kubernetes cluster. Telepresence was initially developed by Ambassador Labs, which creates open-source development tools for Kubernetes such as Ambassador and Forge. We welcome all contributions from the community. You can help us by submitting an issue, pull request or reporting a bug. Join our active Slack group to ask questions or inquire about paid support plans. Telepresence is currently under active development. Register to receive updates and announcements. You can quickly debug locally without waiting for a container to be built/push/deployed. Ability to use their favorite local tools such as debugger, IDE, etc. Ability to run large-scale programs that aren't possible locally.

Introducing Treblle: An agile Software Development Kit (SDK) crafted explicitly for expediting REST-based API development. This cutting-edge toolkit offers unparalleled insights into the intricate metadata of every API request, complemented by real-time monitoring of API traffic. Harness the potency of robust analytics and embrace comprehensive API governance functionalities. Unveil the realm of automated API documentation, empowering your venture with unparalleled efficiency. Treblle transcends the ordinary, introducing automated API security audits for every individual request. The art of streamlining workflows is now within your grasp, while bolstering your defenses through 18+ languages and frameworks, ensuring seamless integration for your enterprise. Elevate your teams' prowess in constructing, shipping, and upholding APIs, all accomplished with unprecedented swiftness.

Craft, troubleshoot, and evaluate APIs with a human touch rather than a mechanical approach. At last, a workflow that you'll genuinely appreciate. Introducing the Collaborative API Design Tool, which provides a platform for creating, validating, and overseeing OpenAPI specifications. This Desktop API client facilitates interactions with both REST and GraphQL. You can make requests and analyze responses seamlessly. Effortlessly create and organize your requests, set up environment variables, manage authentication, produce code snippets, and much more. Dive deep into response details—explore the entire request timeline, including status codes, body, headers, cookies, and additional information. Organize your project with workspaces, folders, and environments, utilizing a drag-and-drop interface for requests, along with straightforward data import and export options. Within a single collaborative API design editor, you can create, modify, lint, troubleshoot, preview, and manage your OpenAPI specifications. Additionally, generate configurations for popular API gateways such as the Kong API Gateway and Kong for Kubernetes. Synchronize your API designs with version control systems like GitHub or GitLab, and deploy directly to API gateways such as Kong with just a click, streamlining your development process significantly. This tool not only enhances productivity but also fosters collaboration among teams in designing robust APIs.

RapidAPI Testing offers a comprehensive solution for functional API testing and monitoring, featuring a user-friendly interface and compatibility with all types of APIs, as well as seamless integration with the RapidAPI Marketplace and Enterprise Hub. This tool empowers users and organizations to ensure the reliability of their APIs through sophisticated functional tests designed for thorough validation. It also allows for centralized monitoring of API tests across diverse geographical locations, enhancing overall efficiency by integrating with CI/CD pipelines and fostering collaboration among teams. Furthermore, RapidAPI Testing supports users in crafting tailored functional test flows that ensure robust validation of REST, SOAP, and GraphQL APIs. With an accessible interface, it presents three distinct options for test creation, making it easy for both developers and non-developers to generate visual, automated, or code-based tests that meet their specific needs. Overall, RapidAPI Testing streamlines the API testing process, ensuring that all users can efficiently verify the functionality of their APIs.

Stoplight is an API Design, Development, & Documentation platform. Stoplight Platform enables consistency, reuseability, quality, and ease in your API lifecycle. Here's what Stoplight Platform can do for you: Stoplight Studio's visual designer makes it easy to design APIs Stoplight Prism mocking allows you to automatically create mock API designs - Invite external and internal users to give feedback and collaborate on your designs - Create faster and more powerful APIs - Use Stoplight Spectral to test and enforce style guidelines To create a pleasant experience, document both internal and externe APIs automatically To quickly scale up API programs that are well-governed, standardized, and collaborative, you can use and integrate design-first workflows.

Keep track of the performance and status of your API endpoints and essential website transactions using a single, user-friendly dashboard. Checkly serves as a proactive reliability platform that merges the advantages of end-to-end testing with continuous monitoring, specifically tailored for contemporary, cross-functional DevOps teams. Emphasizing JavaScript-based open-source technology stacks, Checkly offers a straightforward setup process and integrates smoothly into your existing development processes. As the go-to platform for API and end-to-end monitoring in modern environments, Checkly is programmable, adaptable, and enthusiastically supports JavaScript. Ensure your important website transactions are continuously monitored and validated, while also capturing screenshots to provide immediate insights into operational performance. Automating browser click-flows has become significantly easier; utilize modern open-source tools such as Playwright and Puppeteer for seamless flow automation. Execute your monitoring checks from 20 different locations globally to guarantee that your APIs respond swiftly and deliver the correct data payload consistently. By leveraging Checkly, you can enhance the reliability and performance of your web applications while simplifying your testing processes.

TeejLab is pioneering the integration of data science and machine learning to assist organizations in navigating the complexities of the API economy. As the sole industry solution tailored for API governance on a global scale, we invite you to consider your security and compliance stance regarding mainframe and legacy applications that interface with both internal and external information systems through APIs. Our innovative software composition analysis system stands as the world's first tool designed to uncover shadow, hidden, private, and public APIs using a meticulously curated knowledge base. Just as Google transformed the landscape for websites, TeejLab is revolutionizing the world of Web APIs. Our versatile product suite addresses the diverse API governance requirements of enterprises and communities in a cost-effective manner, while also allowing for the seamless addition of new features as those demands change. Whether your organization is primarily focused on discovering and benchmarking APIs or is a seasoned producer or consumer of APIs looking to enhance your offerings, we have a comprehensive solution to meet your needs and drive your success further. With our expertise, we empower businesses to navigate the ever-changing digital landscape with confidence.

Experience seamless navigation through a tidy and organized interface, enabling you to concentrate on the essential aspects of effectively testing and collaborating on APIs. Firecamp provides a user-centric design alongside a variety of robust features, facilitating an efficient API development process and improving teamwork among members. You can dynamically set variable values for use throughout the platform, ensuring consistency and ease of access. Additionally, create visually appealing API documentation to share with both your team and the wider community. Execute API Collection Tests directly in the terminal or integrate them into your CI/CD pipeline, while also testing and troubleshooting your authentication endpoints with support for multiple authentication methods. This comprehensive approach not only boosts productivity but also fosters a collaborative environment for API development.

Elevate your API journey, streamline consumption, foster collaboration, and enhance developer experience with our versatile, enterprise-grade One APIMarketplace. This platform mitigates API sprawl and simplifies complexities by operationalizing APIs, ensuring they are easily discoverable, consumable, and accessible for collaboration. By enabling faster time to market, One APIMarketplace effectively boosts API adoption through improved accessibility, insightful performance metrics, and increased consumption rates. Equip developers with user-friendly documentation, community support, valuable resources, SDKs, and sandbox environments to further expedite API adoption. One APIMarketplace not only simplifies the discovery and utilization of APIs but also guarantees a seamless experience for both developers and enterprises. With extensive documentation available and the ability to test APIs in a sandbox prior to integration, users can confidently proceed with their projects. Additionally, our robust analytics dashboard provides vital insights into API usage, performance metrics, and user engagement, allowing for informed decision-making.

Testfully offers an extensive array of features, ranging from robust API client capabilities to sophisticated testing and monitoring functionalities. Users can take advantage of versatile cloud and offline storage options, facilitate effortless collaboration among teams, and enjoy straightforward migration, all within a single, comprehensive multi-platform tool. The platform simplifies the transition of data from Postman or Insomnia, allowing for seamless integration into Testfully. With a focus on flexibility and security, users can establish global, environment, and folder variables tailored to either the workspace or individual users. The tool also allows for the customization of authentication methods, parameters, headers, and body content, making it easy to create any HTTP request. Collaboration is made simple as you can invite team members, assign specific roles, and manage folder permissions effectively. Testfully supports major authorization schemes such as OAuth2, ensuring secure and efficient access management. Whether you are dealing with straightforward tasks or more intricate scenarios, Testfully streamlines the testing process without requiring any coding skills, thus making advanced API testing more approachable and user-friendly. Users can execute requests within a folder either simultaneously, sequentially, or in a random order with a single click, enhancing efficiency. Additionally, it allows for response validation and contract testing through a declarative format, further eliminating the need for coding and simplifying the overall testing experience. Overall, Testfully is designed to cater to both novice and experienced users, ensuring that everyone can leverage its capabilities effectively.

Sparrow provides a comprehensive toolkit designed to enhance the entire API lifecycle, guiding research and development teams towards achieving excellence in design-first API development. With cURL, users can easily send API requests while supporting essential methods such as GET and POST. This platform simplifies API interactions by efficiently managing headers, data, and authentication. As a collaborative open-source solution for API development, Sparrow streamlines the creation of outstanding APIs. Through collaborative efforts, developers are able to advance their practices earlier in the development timeline, resulting in more robust APIs and expedited delivery. Users can enjoy seamless parallel testing across various environments, allowing them to gather valuable insights in real-time. Furthermore, Sparrow equips users with powerful tools to secure and manage their API data, along with the option for self-hosting, granting full control over their testing environments. Additionally, users can remain informed about the latest updates, insights, and resources provided by Sparrow to further enhance their development experience. This commitment to continuous improvement ensures that developers are always equipped with the best practices and innovations in API development.

Hoppscotch simplifies the process of creating and testing APIs, enabling quicker product launches. Build APIs with speed, conduct instant tests, and automatically document and share your work. From initial prototypes to final production, you can develop efficiently without the hassle of switching between different tabs. Everything necessary for seamless API development is provided by Hoppscotch. Set up dedicated workspaces for your teams, controlling access as needed. Collaborate with your colleagues in real-time, ensuring smooth teamwork. You can even deploy Hoppscotch on your own servers for added flexibility. Organize your requests into collections or folders to facilitate sharing with your team. Manage your environment variables for consistent usage across your projects. Additionally, keep track of your request history for easy reference. Modify headers, authenticate your requests, generate random data, and explore many more features at your disposal. Test your APIs thoroughly and write assertions to verify responses. Hoppscotch supports over 30 languages, allowing you to use it in your preferred tongue. Keep an eye on all activities within your workspace, tracking who performed actions and when. Utilize your existing SSO provider for easy login to Hoppscotch, and efficiently manage your users, workspaces, and other resources. Furthermore, the intuitive interface ensures that both novices and experienced developers can navigate the platform effortlessly.

A Comprehensive Solution for Developing, Testing, and Securing APIs. Revolutionize the way you create, evaluate, and oversee your APIs. Work collaboratively, execute tests locally, and safeguard sensitive information throughout the entire process. Instant Access, No Signup Required Begin using our platform immediately—eliminate the hassle of cumbersome registration or sign-in procedures. Integrations with VS Code & Desktop Applications Utilize our VS Code extension and desktop applications to ensure a smooth integration with your preferred working environment. Secure Local Storage & Execution Maintain the safety of your data through local storage and execution, which guarantees that confidential information remains on your device. Unlimited Collection Testing Effortlessly test and manage an infinite number of API collections, allowing for seamless scalability across all your initiatives. Create Mock Servers Enhance your development process by setting up mock servers that facilitate rapid testing and simulation of API responses. User-Friendly Testing & Playground Make testing easier with our intuitive interface—explore APIs without the need for any coding. Our advanced enterprise capabilities elevate your API management experience. Reach out to us for more information and to see how we can assist you further!

Create an API in just half an hour and share it with your colleagues or clients, allowing them to explore the API mock without any coding required. By enabling them to interact with the mock, you can gather valuable feedback and refine your design before committing to actual coding, ensuring that the end product truly meets the needs of your developers. Think of it as the DNA of your API—robust, open-source, and designed with developers in mind. It seamlessly combines the simplicity of Markdown with the capabilities of automated mock servers, testing, validation, proxies, and code samples in various programming languages. Often, it can be challenging to predict how an API will be utilized until you engage with it in a coding context. Just as wireframes are essential for UI design, a server mock serves a similar purpose for API development, allowing for rapid prototyping before any code is written. With just two clicks, you can connect Apiary to any repository you choose, giving you the flexibility to decide whether to keep your API Blueprint private or to open it to public collaboration. Every time you commit changes, we ensure that your API documentation stays updated, and we automatically synchronize commits to your repository whenever you make edits at Apiary. This creates a beneficial feedback loop that enhances the quality and functionality of your API over time, streamlining the development process.