8 API Testing Tools You Should Know

1. Qodex

Qodex stands out as one of the top eight API testing tools, showcasing a new era of AI-driven test automation that reshapes the way API testing is done. Instead of spending hours crafting test cases manually, developers can simply describe their testing needs in plain English, and Qodex takes care of generating the test suites automatically.

The platform also maps out all API endpoints automatically, a game-changer for teams working with complex microservices architectures. Let’s take a closer look at how Qodex leverages AI, automation, and CI/CD integration to streamline API testing.

AI-driven automation

Qodex’s AI capabilities cover unit, functional, regression, and OWASP Top 10 security tests, all based on natural language inputs. For instance, instead of writing detailed scripts, you can type something like "test user authentication with invalid credentials", and the platform generates the corresponding test scenarios for you.

One standout feature is its auto-healing functionality, which updates test cases automatically when APIs change. Whether it’s a new parameter or a modified endpoint, Qodex ensures your tests stay current without requiring manual updates, saving developers valuable time and effort.

Seamless CI/CD integration

Qodex fits effortlessly into existing development workflows, supporting both cloud-based and local GitHub executions. With every code commit, teams can run full test suites, quickly identifying issues related to API functionality, security, or performance. This ensures problems are caught early, when they’re easier - and less costly - to address.

Security and compliance testing

The platform excels at identifying vulnerabilities, such as injection attacks, broken authentication, and exposure of sensitive data, through automated OWASP Top 10 assessments. Additionally, its compliance testing tools help teams adhere to industry standards and regulations. Detailed reports document security checks and testing coverage, simplifying audits and ensuring accountability.

Transparent pricing in USD

Qodex offers three pricing tiers to cater to different team sizes and needs:

• The Basic plan is free and includes 500,000 AI tokens, support for up to 500 test scenarios, and a single project space. It’s ideal for solo developers or small startups.

• The Standard plan costs $49 per month and offers 5 million AI tokens, support for up to 20 projects, and priority email support - perfect for growing teams with expanding testing needs.

• Enterprise plans are customized to include unlimited projects, dedicated support, and tailored credits, making them suitable for large-scale operations.

2. Postman

Postman incorporates its AI assistant, Postbot, to simplify API testing workflows. This tool helps automate tasks like creating and managing tests, making the process faster and more efficient.

3. SoapUI

SoapUI is a powerful API testing platform designed for both SOAP and REST APIs. As an open-source tool, it’s widely recognized for its robust features and flexibility. It comes in two versions: a free version and the ReadyAPI Pro version, which offers additional features tailored for enterprise-level needs.

SoapUI also integrates seamlessly with modern CI/CD workflows, making it a valuable tool for automated testing environments.

Integration with CI/CD Workflows

SoapUI supports integration with CI/CD pipelines through various methods, including command-line parameters, a Maven plugin, and compatibility with tools like Jenkins, GitHub Actions, and Docker. Using command-line parameters, tests can be executed without relying on the graphical interface. For those using the Pro version, there are advanced command-line options, such as generating detailed reports, running tests based on specific tags, and maintaining consistent test suites across different environments.

4. Katalon

Katalon is a versatile automation platform designed for testing APIs, web, mobile, and desktop applications. It offers both free and paid plans, with the Free Plan allowing unlimited use of Katalon Studio and up to 2,000 monthly tests.

Integration with CI/CD Workflows

Katalon integrates smoothly with widely used CI/CD tools, making it a great fit for modern development workflows. It supports command-line execution and connects effortlessly with Jenkins, GitHub Actions, and Azure DevOps. Whether you prefer cloud-based solutions or on-premises setups, Katalon's Runtime Engine and TestCloud services provide the flexibility to align with your organization's security and infrastructure needs. These integrations help streamline test automation within your CI/CD pipelines.

Pricing Transparency in USD

Katalon offers straightforward pricing tiers to meet different needs:

• The Free Plan is available indefinitely and includes essential features with community support.

• For advanced capabilities, the Create Plan starts at $229 per user per month. New customers can take advantage of promotional pricing at $1,000 per user annually for up to three licenses.

• The Expand Plan costs $426 per month for one Studio user and one execution session. Opting for annual billing lowers the price to $4,098 per year, saving 20%.

• The Scale Plan is designed for larger teams and is available through custom pricing via a sales consultation.

While Katalon's modular pricing provides flexibility - allowing teams to pay only for the features they need - it can be a hurdle for smaller teams or those in regions with weaker currencies. Separate licenses may be required for additional components, which could add complexity. A comparison table in the next section will further outline these differences.

5. Testsigma

Testsigma is a cloud-based API testing platform powered by AI, designed to support a variety of testing needs. What sets it apart is its natural language approach to creating tests. Instead of writing complex code, teams can craft tests in plain English, making the process more approachable for both technical and non-technical users. Additionally, Testsigma integrates smoothly into CI/CD workflows, streamlining automation and boosting efficiency.

AI-driven Automation

The platform’s AI engine transforms plain English instructions into executable test cases, automatically updating them as API endpoints evolve. This reduces the manual effort typically required to maintain test suites. Testsigma also excels in accurate element detection and self-healing tests. When API responses change - such as modifications in structure or the addition of new fields - the platform adapts existing tests to accommodate these changes. This is a game-changer for teams managing APIs that undergo frequent updates, preventing disruptions in test automation.

Seamless CI/CD Integration

Testsigma is built to work effortlessly with CI/CD pipelines, integrating with tools like Jenkins, GitHub Actions, GitLab CI, and Azure DevOps. It provides REST APIs and webhooks that allow teams to trigger test executions directly from their deployment workflows. Whether you need scheduled or on-demand test runs, Testsigma offers the flexibility to fit various development processes.

Test results sync automatically with your CI/CD pipeline, delivering instant feedback on API performance after deployment. To help teams quickly identify and resolve issues, the platform generates detailed reports featuring screenshots, logs, and execution videos.

Security and Compliance Testing

Testsigma includes automated security checks to validate critical aspects like authentication, authorization, and data encryption. It can also detect common vulnerabilities such as SQL injection, cross-site scripting, and improper access controls within API endpoints.

For teams with compliance requirements, Testsigma offers detailed audit trails that log test executions, timestamps, user actions, and results. It also supports data privacy regulations by enabling teams to mask sensitive data in test reports and logs, ensuring compliance with privacy standards.

Pricing Options in USD

Testsigma provides clear pricing, making it easy to match its offerings to your team’s budget. A free tier is available, allowing up to 1,000 test executions per month. This plan includes essential API testing features and basic integrations, though it limits the number of parallel test runs.

Here’s a breakdown of the paid plans:

• Startup Plan: $99/month, includes 5,000 test executions and up to 5 parallel runs.

• Business Plan: $299/month, offers 15,000 test executions and 15 parallel runs.

• Enterprise Plan: Custom pricing, with unlimited executions, unlimited parallel runs, dedicated support, and on-premises deployment options.

Unlike some platforms that charge separately for different testing types, Testsigma’s pricing covers API, web, and mobile testing under one subscription. This makes it a cost-effective choice for teams working across multiple platforms.

6. JMeter

JMeter is a free, Java-based tool designed for API performance testing. While it was originally built for testing web applications, its capabilities have expanded to include support for SOAP/REST web services, databases via JDBC, FTP, LDAP, and message-oriented middleware like JMS. Thanks to its Java foundation, JMeter works seamlessly across Linux, Windows, and macOS.

One of its standout features is native multi-threading, which allows multiple thread groups to run at the same time. This makes it ideal for simulating realistic user behavior and testing how APIs perform under varying load conditions.

Integration with CI/CD Workflows

JMeter isn't just about performance testing - it fits neatly into modern CI/CD workflows. Using its command-line interface (CLI mode), JMeter can run in headless mode, saving resources and making it perfect for large-scale test executions in automated pipelines. For distributed testing, JMeter supports a master-slave setup, where multiple machines work together to generate concurrent loads. This setup ensures no single machine gets overwhelmed, allowing teams to pinpoint performance issues early in the development cycle.

JMeter’s Java compatibility also makes it easy to deploy on nearly any cloud platform. After testing, detailed HTML reports provide instant feedback, helping teams address issues quickly after deployments.

Pricing Transparency in USD

JMeter operates under the Apache 2.0 license, meaning it’s completely free for both commercial and non-commercial use. The only costs involved are for the infrastructure and team resources needed to manage distributed testing environments. This pricing model is especially appealing for teams aiming to maintain strong API testing capabilities without overspending.

7. Playwright

Playwright, developed by Microsoft, is a versatile cross-browser automation framework that includes a powerful HTTP client for API testing. It’s especially handy when testing APIs that rely on browser-specific features like cookies, local storage, or session management. By allowing validation of responses in a real browser context, Playwright bridges the gap between API testing and browser-based scenarios.

The framework supports multiple programming languages such as JavaScript, TypeScript, Python, C#, and Java. This flexibility allows development teams to use the tools and languages they’re most comfortable with. One standout feature is its auto-wait capability, which reduces flaky tests by waiting for elements and network requests to fully load before proceeding. These features make Playwright a solid choice for teams working in modern CI/CD environments.

Integration with CI/CD Workflows

Playwright is designed to fit seamlessly into headless CI/CD pipelines. It supports parallel test execution across different browsers and generates detailed reports that include screenshots, videos, and network logs - making it easier to identify and resolve issues quickly.

The framework also offers Docker support, ensuring consistent test environments across all stages of development. With official GitHub Actions integration, teams can streamline their automated workflows effortlessly. Additionally, Playwright provides advanced debugging tools, such as automatic retries for failed tests and a trace viewer that lets developers step through test executions frame by frame.

Pricing Transparency in USD

Playwright is available under the Apache 2.0 license, meaning it’s completely free for both commercial and personal use. There are no hidden costs, licensing fees, or subscription charges. The only expenses you might incur are related to infrastructure, such as running tests in cloud environments or maintaining dedicated test servers.

8. Swagger UI

Swagger UI is a free, open-source tool that transforms API documentation into an interactive testing platform. Instead of static endpoint descriptions, it offers a live interface where developers can explore and test APIs directly from their browser. This hands-on approach makes it easier for teams to understand API functionality without diving into complex code.

The tool generates interactive documentation from OpenAPI specifications, providing a clear view of endpoints, parameters, and expected responses. Developers can execute API calls directly from the interface to experiment with different parameters and instantly see the results.

With a 4.5/5 rating on G2, users frequently highlight its clean design and ability to save time by auto-generating documentation and simplifying endpoint testing.

Support for Security and Compliance Testing

Swagger UI comes equipped with features to support security and compliance efforts. It enforces security policies, tracks API usage, and helps identify vulnerabilities early in development. The interactive documentation also serves as a useful resource for auditors and compliance teams, offering transparent insights into endpoint behaviors and helping to uncover unusual usage patterns.

Integration with CI/CD Workflows

Swagger UI fits seamlessly into modern development pipelines. Whether used as a standalone web application or embedded into existing systems, it ensures API documentation and testing are always accessible within the development environment. Its lightweight design minimizes any impact on CI/CD processes. Teams can even automate the creation and updating of API documentation as part of their build pipelines, ensuring the testing interface stays in sync with the latest API updates. This integration makes it an efficient and practical tool for development teams.

Pricing Transparency in USD

Swagger UI operates under the Apache License 2.0, making it completely free for personal and commercial use. There are no licensing fees, subscription costs, or usage restrictions. The only potential expenses might come from infrastructure needs, such as hosting the documentation interface or integrating it into existing systems. However, these costs are typically low due to the tool's minimal resource requirements. This open and cost-free model further solidifies Swagger UI as a valuable addition to any API testing toolkit.