The Best API Testing Tools for 2024

Artem Golubev

Test Automation Tools

With so many software projects now relying on APIs for internal and external purposes, your team is likely to check regularly to make sure you’re using the best API testing tools possible. To get your team up to speed quickly and with the latest information, here are some of the best API testing tools currently out in the market in 2024.

testRigor

testRigor is an extremely powerful test automation system that features AI-powered test creation and the ability to grab your existing manual tests and convert them into no-code executable tests. While API testing is not the primary focus of testRigor, it is still an excellent tool for API testing. You can also test web apps, native desktop apps, as well as native and hybrid mobile applications. So in a nutshell, testRigor is a one-stop test automation tool, ideal for end-to-end testing.

testRigor offers three easy-to-understand offerings:

The public open source offering is free and powerful, with the ability to have unlimited users, test cases, and suites. In this scenario, tests are limited to 1 parallelization with all tests, and the results are public.
The private offering is popular at $900 per month and includes one private test suite and 1 parallelization, plus essential support. In this scenario, tests and test results are private, with unlimited users and test cases. There is a free trial option available for this tier.
Finally, testRigor offers a highly customizable enterprise tier, which you can tailor to best suit your needs. This offering includes a dedicated customer success manager to help ensure your success with the product, Slack-based support, single sign-on, and an SLA. As with all other versions of testRigor, unlimited users and unlimited test cases are included. There is also an option to have an on-premise installation.

Postman

Perhaps one of the most commonly used tools in the area of API testing, Postman is a favorite for many teams working with APIs.

Initially, a Google Chrome browser plugin focused on testing API services, Postman is now also possible to run on Mac and Windows operating systems and is extremely useful for testing purposes.

At its core, the Postman features allow you to monitor APIs, run API requests, perform debugging, and create automated tests. The Postman interface enables you to extract web API data and write Boolean tests without being based on the command line.

Postman also supports a range of formats like Swagger and RAML and offers built-in tools, workspaces, and collections.

Postman is a staple, easy-to-use tool for many software teams in the field of software development.

In terms of cost, Postman has a range of offerings:

The Free offering allows teams to get started with designing, developing, and testing APIs.
The basic tier costs $12 per user per month when billed annually or $15 per month when billed monthly. It allows for team collaboration to facilitate the API design, development, and testing process across an entire team, with unlimited collaboration for teams of 4 or more. For example, it includes support for a custom domain, collection recovery for 30 days, 10 integrations, and 10x calls to the Postman API.
The Professional offering costs $29 per user per month when billed annually, or $36 per month billed monthly. In addition to what’s covered in Basic, it includes single sign-on via SAML, collection recovery for 90 days, static IP addresses for API testing, private workspaces, roles and permissions, 5 custom domains, 50 integrations, and 100x calls to the Postman API.
While all other plans can be signed up for online, Enterprise requires contacting sales and is listed at $99 per user per month billed annually. Where the Professional plan offers SSO, the Enterprise plan takes it further with automated member provisioning and de-provisioning via SCIM, and supports identity and access management, including user governance. The Enterprise tier also includes 25 custom domains, 100x calls to the Postman API, and 100 integrations, including GitHub and GitLab. Other perks include domain capture, enterprise support, customer success, and custom payment options.

Apigee

Apigee is another prominent API testing tool built for cross-cloud API testing and accessible via various editors like Swagger.

Powered by JavaScript, Apigee is a multistep tool that facilitates measuring and testing performance related to your APIs.

Apigee can allow your team to track API traffic, response time, and error rates, which can really help out a lot when it comes to identifying performance issues related to your APIs.

Additionally, Apigee is able to handle APIs that contain large amounts of data, and allows for the creation of API proxies using the OpenAPI Specification with its related cloud deployment.

In terms of cost, Apigee invites interested teams to talk to their sales team to discuss pricing. There is also an option for a free trial to check features and compatibility.

Apigee offers the following packages to choose from:

You can evaluate features in a sandbox environment for a period of 60 days, limited to 100,000 API calls per month, with no SLA and 2 environments to test with.
The Standard package allows for setting up and running an API program with up to 180 million API calls per year, 5 environments for the organization, 30 days of analytics reports, and an SLA that includes 99% uptime.
The Enterprise package enables customers to build and scale API programs throughout their organization. This tier includes 1.2 billion API calls per year with 10 environments across 2 organizations, support for hybrid deployment, 3 months of analytics reports and uptime of 99.9% in the SLA.
Enterprise Plus helps cultivate an ecosystem of partners and developers by facilitating the operation of an entire digital business platform. This tier allows up to 12 billion API calls per year for 30 environments over 6 organizations, with 14 months of analytics reports, support for hybrid deployment, and uptime of 99.99% in the SLA.

SoapUI

SoapUI is a popular headless functional testing tool that facilitates the testing of REST and SOAP APIs. SoapUI offers both free and paid versions of the product.

With the free, open-source version of SoapUI, users have full access to source code to achieve their needs. This offering is recommended for teams just getting started with automation or those who need a budget-friendly option. Using free SoapUI, users can leverage reusable scripts to re-use load tests and security scans for functional testing, and the product offers both drag-and-drop and point-and-click features for fast, easy test creation.

SoapUI also offers the paid tool ReadyAPI, allowing customers to take API testing much further. In terms of pricing, ReadyAPI from SoapUI has a few offerings called Modules, which all have a 14-day trial period. It’s important to note that these offerings are not tiers but rather feature sets that focus on specific areas like tests, performance testing, and virtualization:

The API Test Module starts at $829 per license billed annually. This tier supports scriptless and custom scripting testing, data-driven testing, CI/CD automation, and AI-driven test creation.
The API Performance Module starts at $6,769 per license billed annually and provides the features of parallel API load tests, flexible load generation, server monitoring, and pre-built load templates.
The API Virtualization Module starts at $1,270 billed annually. Highlights include a simple virtual service creation, sharing and deploying virtual services, simulating server-side behavior, and managing and generating mock data.
Finally, there is the option to combine these Modules as a bundle by requesting a custom quote.

SoapUI also has another tool called TestEngine, which is a test runner designed for automating SoapUI and ReadyAPI tests at what they call a tremendous scale.

Assertible

Assertible is another popular API testing tool with a focus on reliability and automation of API tests at every point in the process, including testing and monitoring across deployments and environments.

Assertible has several different Plans available for purchase:

The Personal plan is free and provides access to all of the Assertible features for automated testing and uptime monitoring. This plan allows 1 to 2 members with 2 web services, 10 tests per service, result retention up to 1,000, and “standard” monitoring frequency using two monitors that check your services daily, hourly, and thirty-minute schedules.
The Standard plan costs $25 per month for 1 member to use, and goes up to 25 web services with 500 tests per service, up to 5,000 results retained, and an “upgraded” monitoring frequency that includes the same schedule as “standard” monitoring, plus 1, 5, and 15-minute schedule frequencies.
The Startup plan costs $50 per month and basically extends the Standard plan to 10 members instead of 1, to better support collaboration in a team environment.
The Business plan costs $100 per month and essentially doubles the Startup plan, going from 10 members to 20 members supported, with 50 web services, 1.000 tests per service, and result retention up to 10.000.

All of the paid plans offered by Assertible can be tried out with a month’s free trial.

There are even more API testing tools out there, but this list includes some of the most popular and robust offerings on the market today.

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