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.

It works: Codeless testing Give your entire team the ability to create and maintain automated tests. Not just developers. Meet your testing demands fast. You can get full coverage of your tests in days and not months. Our natural-language tests are very resistant to code changes. Our AI will quickly repair any test failures. Continuous Testing is a key component of Agile/DevOps. Push features to production in 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 way to create resilient end-to-end test cases, whether they are codeless or coded. Testim allows you to create codeless, stable tests that leverage our AI. You also have the option to export your tests as code. Testim's JavaScript API is available to you and your IDE. This allows you to debug, modify, or refactor your tests. To keep them in sync, store them in your version control system. Run tests on every commit. Testim is used by millions of customers every month, including NetApp, Wix and JFrog. Find out more on our website.

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.

Cerberus Testing automates continuous testing at scale with low-code software. The solution will eliminate the need to implement an internal testing framework for years. The product allows you to iterate quickly through your testing lifecycle: from test repository, execution, and reporting. The solution allows teams to collaborate from the use-cases creation to the execution of test cases on a variety of browsers and devices. To execute your test at scale, you can use your own or external robots infrastructure. This allows you to concentrate on your business value. It supports many integrations to speed up implementation, such as Bitbucket and Slack. It is open-source and maintained by many digital and retail players, including La Redoute and Decathlon, Adeo and Norauto.

Tuskr is a powerful and easy-to-use test management tool. You can manage test cases, conduct test runs, and even optimize your testing workload. You can also integrate with your current bug and time tracking software. Tuskr offers a free 30-day trial with sample data during the evaluation. It also offers a generous free plan.

API Tester is a mobile app for IOS and Android for testing and using APIs. It's a completely free API testing tool with a minimalistic interface and, at the same time, rich functionality that allows users to do very complex tasks on a small screen. - Test all types of APIs: REST, GraphQL, WebSocket, SOAP, JSON RPC, XML, HTTP, and HTTPS. - Perform all HTTP request methods: GET, POST, PUT, PATCH, DELETE, HEAD, etc. - Make the API calls with any kind of request data encoding and transfer type like query params, FormData, raw data, etc. Advanced settings allow you to skip TLS, disable redirects, and adjust timeouts. - Import requests or collections by cURL, link, or file from your device: Swagger, OpenAPI, Postman, and YAML collections are supported. - Share requests in a second using a deep link and cURL command. - Powerful GraphQL editor with full-scale experience: body editor with Queries, Mutations, Subscriptions, and syntax support; variables editor, documentation. - WebSocket testing tool is available too: handles connection and message exchange via WS or WSS. So you can easily connect with APIs you are working with from everywhere in the world and leave your laptop at home!

Utilize Telerik Fiddler HTTP(S) proxy to capture all internet traffic between your computer and external sites, allowing you to analyze that traffic, set breakpoints, and manipulate both requests and responses. Fiddler Everywhere serves as a versatile web debugging proxy compatible with macOS, Windows, and Linux platforms. You can capture, inspect, and monitor all HTTP(S) communication, facilitating the mocking of requests and troubleshooting of network problems. This tool is applicable to any browser or application, enabling you to debug traffic across macOS, Windows, Linux, and mobile devices running iOS or Android. It guarantees that the necessary cookies, headers, and cache settings are properly exchanged between client and server. Supporting diverse frameworks such as .NET, Java, and Ruby, Fiddler Everywhere empowers you to mock or alter requests and responses on any website efficiently. This straightforward approach allows for testing website functionality without the need for code alterations. By employing Fiddler Everywhere, you can effectively log and analyze all HTTP/S traffic between your system and the wider internet, streamlining your debugging process.

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.

ZAPTEST is a leading Free and Enterprise software test automation and RPA tool. Computer Vision technology allows cross-platform digital interface automation for UI and API. This combined with our 1SCRIPT methodology, seamless automation, parallel execution, and unlimited licenses, will result in a testing suite that generates up to 10X ROI. ZAPTEST will automate any procedure you can do via any digital interface (live app or mockup). Discover the unparalleled advantages of partnering with ZAPTEST Our partners are essential in providing businesses with innovative, industry-leading automation solutions that transform software testing and RPA processes. ZAPTEST empowers organizations with a unified automation platform that streamlines both software testing and business operations. Our unlimited licensing model ensures you can scale effortlessly, transforming your business into an agile, efficient powerhouse.

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 provides a comprehensive suite of tools that streamlines the entire API lifecycle, empowering research and development teams to adopt optimal practices for API Design-first development. Users can design and troubleshoot APIs using a robust visual editor, paired with JSON Schema support for straightforward descriptions and debugging. The platform automates the API lifecycle through features such as test generation from API specifications, visual assertions, built-in response validation, and integration with CI/CD pipelines. Additionally, it allows for the creation of visually appealing API documentation, which can be published to a custom domain or securely shared with collaborative teams. With a local and cloud mock engine, Apidog generates realistic mock data based on field names and specifications, eliminating the need for script writing. High-quality tools are essential for fostering team collaboration while preventing redundant tasks. Users can easily describe their API during testing, generating JSON/XML schemas with just a click, and can generate test cases from APIs, visually add assertions, and create complex test scenarios with branches and iterations with remarkable ease. This seamless integration of features ensures that teams can focus on innovation rather than repetitive tasks.

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. Through the GUI, our solution allows you to collaborate, execute and fix your tests and communicate at all levels to ensure test plans and test results are provided with the right level of details. Alithya GoTest is platform-agnostic and will allow you to seamlessly test desktop, web and mobile applications. You will not have to spend months building, maintaining and integrating your test platform into your development workflow, which allows your development team to focus on delivering value and quality. Compared to more traditional solutions, Alithya GoTest is the only tool on the market that allows you to completely test your software from end-to-end using continuous testing in a DevOps process. Contact our top-notch bilingual support team or use our consulting, coaching or online training resources to get up to speed in no time. Benefit from our growing list of pre-made test suites for professional ERP platforms like Oracle Fusion Cloud to ensure updates are not breaking your software solution.

HttpMaster is a HTTP debugging and testing tool specialized in testing web API applications and REST web services. Core features: - HttpMaster project to store complete definition of request items. - 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 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. - Support for 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.

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.

Treblle is a federated API Intelligence platform that unifies API visibility, governance, and security in a single enterprise-grade solution. Designed for complex environments, Treblle connects seamlessly through one integration and supports deployment on-prem or in private cloud—meeting even the strictest regulatory and data residency requirements. Once integrated, Treblle instantly maps your entire API landscape with automatic discovery, generating real-time inventories and eliminating shadow APIs. Its observability tools track every request and response, surfacing performance issues, anomalies, and SLA breaches across all services. Advanced analytics give teams insights into traffic, latency, endpoint usage, and client behavior, making debugging, optimization, and scaling easier and 15 times faster. Security is built-in, not bolted on. Treblle provides runtime protection, threat detection, schema validation, and governance policies to safeguard APIs across environments. It empowers DevOps and platform teams to implement shift-left strategies and enforce consistent practices across the lifecycle. With its AI-powered Integration Assistant, Treblle simplifies onboarding and improves developer workflows. Whether you’re running internal microservices or customer-facing APIs, Treblle gives you the clarity and control to move faster, reduce risk, and scale with confidence.

Enjoy a unified testing experience across various test types. You can utilize the same test scripts regardless of whether you're assessing a web application on numerous browser, operating system, and device combinations, checking the functionality of your APIs, or conducting extensive load tests. Our enterprise-ready SaaS platform, hosted in the cloud by Testable, enables you to execute tests either in the cloud or on-premises with your preferred open-source tools, while we manage the test execution, real-time reporting, detailed analysis, and secure storage in the cloud. Additionally, you have the option to securely deploy our testing platform on your own infrastructure, safeguarded behind your firewall. With modern, scalable, and flexible packaging options, including a convenient one-click Kubernetes Helm package, you can run functional tests across multiple browsers, OS, and devices in a single test run. Furthermore, you will have access to a real-time report that showcases live interactive sessions, videos for each virtual user, screenshots, assertions, performance metrics, trend analysis, and a wealth of additional insights to enhance your testing process. This comprehensive approach ensures that you have everything you need to optimize your testing efforts effectively.

Develop and evaluate HTTP and RESTful web service requests. Execute data-driven test scenarios and analyze the outcomes using any spreadsheet software. Additionally, employ a graphical user interface-based randomization editor, allowing for the inclusion of attachments, whether MTOM is utilized or not. Carry out your testing processes and examine aggregate test results, with the ability to revisit these findings at a later date. Import WSDL specifications to construct your SOAP tests, incorporating assertions and facilitating data transfer across various test steps, cases, folders, and repositories. Modify variables encompassing different formats such as strings, integers, and current date and time values, including the use of relative dates with various formatting options. Furthermore, ensure that your testing framework is adaptable for future expansions or changes in testing requirements.

Testing and monitoring your web services has never been simpler. With Assertible's automated quality assurance tools, you can ensure the reliability of your essential infrastructure by testing and monitoring web services throughout various deployments and environments. Assertible acts as a dependable first line of defense against web service failures, offering straightforward and effective assertions for your APIs and websites. By minimizing false positives in your automated quality assurance tests, you can trust that your APIs remain in good health. While keeping your tests current may seem daunting, Assertible streamlines this process by allowing you to automatically synchronize your API tests with the most recent updates to your specifications. As you modify responses, parameters, headers, and additional elements, updating your Assertible API tests becomes a hassle-free task that requires just a simple click to sync. Furthermore, Assertible seamlessly integrates with your existing tools, enabling functionalities like executing your web application tests upon code pushes to GitHub or sending alerts to Slack in case of any failures, thus facilitating a smoother workflow. By leveraging these features, teams can enhance their development efficiency while maintaining high-quality standards.

BlazeMeter offers an enterprise-ready platform that is open-source based, integrating all essential features to facilitate both left and right shift testing. With a user-friendly interface, you can easily create tests or adapt your existing scripts to execute them at scale as a part of your ongoing testing strategy. Generate comprehensive reports and analyze historical trends to enhance your testing process. This allows you to dedicate more time to innovation instead of toolchain upkeep. Continuous testing plays a crucial role in achieving quality, volume, and speed in your deliverables. However, the challenges of integrating, managing, learning, and switching between various tools can consume precious time and resources. BlazeMeter simplifies this process with a highly intuitive platform that encompasses everything you need. It guarantees a complete shift left testing experience, enabling you to impress the market with your advancements. BlazeMeter equips you with all necessary elements for continuous shift left testing, providing options to work with CLIs, APIs, UI, open-source tools, and beyond. As a result, you can significantly reduce the time spent on setup, maintenance, training, and everyday usage, ultimately streamlining your workflow. This efficiency not only enhances productivity but also empowers teams to focus on what truly matters: delivering exceptional products.

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.

Evaluating and verifying REST services in Java can be more challenging compared to using dynamic languages like Ruby and Groovy. However, REST Assured introduces a level of ease and accessibility akin to those languages within the Java ecosystem, making the process more straightforward for developers. By leveraging REST Assured, Java programmers can streamline their testing efforts and enhance productivity significantly.

Loader.io offers a complimentary load testing service designed to evaluate the performance of your web applications and APIs by simulating thousands of simultaneous connections. You can easily register your application for testing through either the web interface or API. During the testing period, we will generate connections to your application, allowing you to observe the process in real-time. After the test is complete, you can conveniently share the results with your team for further analysis and discussion. This tool is invaluable for ensuring your application can handle high traffic effectively.