Best Free Load Testing Tools of 2025

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.

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.

Open Architecture for Building and Running Load Testing. You need to quickly load test your home page, one URL within your site, or a mobile API endpoint. You can quickly create simple tests and scale them to thousands of users in a matter of minutes. Apache JMeter and WebDriver go beyond being open-source tools for cloud load testing. They are vibrant communities with deep knowledge that are built on real user needs. Open load tests allow you to write load tests in the languages and utilities that you use every day. You can create custom tests in Python or PHP. Load testing is easy, cheap, and open to everyone. This is possible thanks to an open architecture that allows tuning and control over the setting up of cloud load agents.

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.

We utilize open-source load testing tools both in the cloud and on-premise, allowing for seamless test creation and reporting within a single, easily shareable platform for your team. By integrating load testing early in the development process, organizations foster a lasting culture centered around performance and reliability. As companies expand and their systems become more intricate, the importance of maintaining high performance increases. Discover how performance testing can be leveraged as a critical competitive edge to facilitate rapid delivery. Many enterprises face performance testing challenges that may conflict with their compliance and security requirements. Explore how Flood can address these issues effectively within your organization. Additionally, adopting these testing practices not only enhances system efficiency but also promotes collaboration among team members, leading to better overall outcomes.

All-in-one cloud testing platform for performance testing, load testing, website speed testing and website UI testing. Mobile applications and API endpoints are all covered. JMeter testing is easy from multiple cloud locations, with thousands of users. Apache JMeter allows you to see real-time performance metrics of your website and APIs from the cloud. You can monitor changes over time and receive advice on how to speed up page loading times. We run your tests on cloud instances at set times and notify you if anything goes wrong. To find rendering issues, invalid HTML, missing or incorrect CSS, load your web pages and websites in mobile emulators. In seconds, schedule runs and inspect the rendered images on all devices. Simulate your site on different screen sizes and resolutions. Take screenshots of two websites in seconds. To check for differences, you can compare the generated screenshots using a threshold.

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.

The most powerful open-source load testing tool for stress and load testing. When you are working with security regulations, get your dedicated IPs from around the world to simulate user loads for your load testing. Your automated Selenium test scripts can be used for performance testing. Instead of using local data centers, create load from other regions to test for load. Amazing reporting features that display tabular and graphical data allow you to monitor app performance during tests. You can now shift left and integrate performance tests into your DevOps process using your favorite CI tool. APM tools can monitor the app infrastructure. Performance Testing is a type software testing that ensures that the application performs well under the user load. Performance testing is not intended to find bugs, but to identify performance bottlenecks. It assesses the system's quality attributes.

LoadForge harnesses the power of the cloud to efficiently scale vast amounts of simulated users for cost-effective load testing of your website, store, API, or application, starting at just $29 a month. With expertise in authentication, forms, high scale, JSON POSTs, GraphQL, REST, and more, LoadForge stands out as a leader in web load testing. Whether you're preparing for a major launch or looking to bolster your defenses against DoS attacks, LoadForge can effectively load test any website, web app, API, or microservice, including automated load testing for new features and SQL load evaluations. The platform not only helps you grasp your app’s performance metrics and identify failure points but also utilizes AI to pinpoint performance problems automatically. Enjoy unlimited testing capabilities without restrictions on the number of tests you can perform; run as many tests as needed, and manage multiple applications simultaneously. LoadForge is designed to be powerful yet user-friendly, making web load testing both straightforward and customizable, accommodating everything from initial tests with hundreds of users to intricate scenarios involving millions. With LoadForge, you can confidently assess your application's resilience under various conditions!

BlazeMeter offers an enterprise-ready, open-source platform that consolidates all essential features for shifting testing both left and right. With our user-friendly interface, you can effortlessly create tests or utilize your existing scripts, executing them at scale as part of your continuous testing approach. Additionally, you can conduct tests, generate comprehensive reports, and observe historical trends. This allows you to allocate more time to innovation rather than managing your toolchain. Continuous testing is vital for achieving quality, volume, and speed in delivery, but juggling multiple tools can drain precious time and resources. BlazeMeter simplifies this process through an extremely intuitive platform that encompasses everything you need. It empowers you to implement complete shift-left testing, enabling you to impress the market with groundbreaking innovations. BlazeMeter equips you with all necessary elements for continuous shift-left testing, allowing you to work seamlessly with CLIs, APIs, UIs, and various open-source tools. Plus, you can save significant time on setup, maintenance, and everyday usage, ensuring a more efficient workflow. In this way, BlazeMeter not only enhances productivity but also drives your testing strategy to new heights.

Utilize OctoPerf to save between 50% to 70% of your time when creating Thread Groups, also known as Virtual Users, compared to Apache JMeter™. Our Cloud load testing infrastructure allows you to effortlessly scale up to one million users. While many features of traditional tools may not cater to the needs of modern load testers, we prioritize the essential functionalities, continuously enhancing OctoPerf to provide an exceptional user experience. Moreover, OctoPerf stands out for its user-friendliness, offering contextual documentation, engaging video tutorials, and responsive live chat support. With everything you need, you'll be able to conduct load tests like a seasoned professional in no time. There’s no vendor lock-in, as you can easily export your work from OctoPerf to JMeter JMX files. Leverage auto-correlation rules and frameworks, along with test validation, to swiftly build virtual users. Spin up load test agents worldwide within minutes, create tailored visualizations, track results over time, and generate customized report templates to meet your needs. With OctoPerf, the process of conducting efficient load tests becomes not just simpler but also far more powerful.

Loadster is a load test platform for websites, web apps, and APIs. Loadster can identify a site's breaking point before you users. To find bottlenecks, improve performance, or prevent crashes, create realistic test scripts.

Eggplant empowers organizations to create incredible digital experiences. We help businesses monitor, analyze and improve their customer experience. Eggplant is used by companies around the world to outperform their competitors, increase productivity, and delight customers. How does Eggplant work? How? By dramatically improving the quality, responsiveness and performance of their software apps across different interfaces and platforms, browsers and devices -- including mobile, IoT and desktop -- in agile, DevOps and innovative application and data environments.

HeavyLoad is a free stress testing application designed to push your computer to its maximum capabilities. It is compatible with all versions of Windows, including both client and server editions, whether they are 32-bit or 64-bit, as long as they are still supported by Microsoft. This tool allows you to assess the reliability of your workstation or server under extreme conditions, ensuring they can handle heavy workloads. For added convenience, you can opt for a portable version of HeavyLoad, enabling you to run it from a USB stick and use it as a mobile benchmarking solution. It's essential to evaluate your critical systems beforehand to determine their resilience against high-stress scenarios with our performance testing software. The user-friendly graphical interface and clear visual feedback mean that anyone can utilize this benchmarking tool without needing specialized expertise, making it accessible for all users interested in system performance.

Looxy.io strives to become the ultimate destination for all your software testing needs. The platform is set to expand its offerings by incorporating a variety of new tests, such as web page performance assessments, load testing, penetration testing, and web application security evaluations, among others. Every test will be user-friendly and complimentary, ensuring accessibility for all users. However, for those interested in utilizing advanced testing configurations, scheduling options, or increased testing frequency, an affordable subscription may be required. This approach aims to cater to both casual users and professionals seeking comprehensive testing solutions.

PFLB specializes exclusively in performance testing. We help companies identify and resolve performance bottlenecks, such as slow database queries or API calls that are not performing well. We are the company of choice for clients who need performance testing across a wide range of technologies, such as web and mobile applications and core banking systems. We offer a wide range of solutions for JMeter, LoadRunner and other environments. PFLB is a load testing platform that allows companies to perform efficient and scalable performance test. PFLB is a global leader in performance testing with over 15 years' experience.

Cavisson NetStorm offers an affordable and user-friendly solution designed to enhance the performance of enterprise applications. This robust load generator delivers precise assessments of Client Perceived Response Time (CPRT), allowing IT firms to uphold their Service Level Agreements (SLA) with confidence. Its cutting-edge technology adeptly manages various load variables, as well as user, application, and network realism. NetStorm has established itself as a reliable choice, identifying root causes of issues that previous legacy systems could not, leading numerous Fortune 100 companies to adopt it. With its capability for extensive load generation, it ensures accurate evaluations of client perceived response times. As the web landscape evolves, providers are increasingly focused on bolstering profits while users are becoming more critical of performance. By implementing NetStorm, businesses can allocate their IT expenditures more wisely, ultimately improving their operational efficiency. Furthermore, this strategic investment not only enhances user satisfaction but also strengthens the company’s market position in a competitive environment.

Apache JMeter™ is an open source tool developed in pure Java, intended for conducting load tests to assess functional behavior and performance metrics. Initially created for web application testing, its capabilities have grown to encompass various testing functions. This versatile software can evaluate the performance of both static and dynamic resources, including web applications that are dynamic in nature. By simulating substantial loads on a single server or a network of servers, it allows users to examine the system's resilience and analyze its performance across different types of loads. As a result, Apache JMeter has become an essential tool for developers and testers seeking to ensure optimal performance and reliability in their applications.