10 free tools for API design, development, and testing

These full-fledged free-tier services and indispensable utilities will have your API up and running in no time

10 handy no-cost tools for API development

10 handy no-cost tools for API development

The rise of RESTful APIs has been met by a rise in tools for creating, testing, and managing them. Whether you’re an API newbie or an expert on an intractable deadline, you have a gamut of services to help you get your API up and running quick, and many of them won’t cost you a dime.

Following is a sampling of free services for working with APIs: load testers, API designers, metrics collectors, and much more. Some are quick and dirty applications to ease the job of assembling an API. Others are entry-level tiers for full-blown professional API services, allowing you to get started on a trial basis and later graduate to a more professional level of (paid) service if and when you need it.

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aws free tier

Amazon AWS Free Tier and Amazon API Gateway

The Free Tier for AWS provides developers with no-cost access to most of what AWS offers—including Amazon API Gateway. Your free API Gateway maxes out at 1 million API calls per month, but it’s enough to give you a taste for how things work.

The full, for-pay version of Amazon API Gateway allows you to build front-end APIs for applications built on EC2, AWS Lambda, or “any web application,” with meta-tools like traffic management, API version control, and monitoring all part of the package.

ibm cloud

IBM Cloud API Management

Like AWS, IBM Cloud offers a free tier that is robust enough to provide developers with a taste of what’s available, but not full-featured enough to build full-blown production applications. And like AWS, IBM Cloud offers an API management tool on that free tier, API Connect.

API Connect was originally just a tool to create APIs and hitch them up to live code. It has since added tools for enforcing policies around APIs, encouraging discovery, creating composite API designs, and “[integrating] cloud services with enterprise systems of record.” The service has a free tier of 50,000 API calls a month—more than enough to get one’s feet wet.



Runscope offers a web-based toolkit for testing your APIs to make sure they function properly, return valid data, and can be debugged. You can even import test plans using the Swagger 2.0 API definition standard, along with a slew of other common formats, including the format Runscope uses for its own testing products. There is no free tier, but 14-day free trials are available for all pricing plans.


Restlet Studio

Billed as a “web IDE for API design,” Restlet Studio describes APIs with a set of visual tools. This includes setting methods or query parameters, autogenerating skeleton code for the APIs, and even autocreating client SDKs. Both Swagger and RAML are supported; in fact, you can toggle between them while working on an API.

The free plan supports only one API, but you get an unlimited number of calls to that API in testing and 1,000 calls in production. That’s right, you can use the free tier to deploy to production, albeit without support for the likes of CI/CD or custom domain names.



APImetrics is an API monitoring and alerting service that includes a visual API designer, support for both REST and SOAP APIs (easing the move from the latter to the former), a workflow system that allows multiple API calls to be triggered in sequence, and dashboarding for everything that needs to go right but could go wrong. There is no free tier but rather a 14-day trial version of the “Grande” level of service—10,000 calls per day, 300,000 per month, for $200 per month.



JsonStub is a web interface that allows you to create quick mockups of API endpoints, returning static text (such as a JSON response) to test a front end that queries for data. It isn’t very involved, but it isn’t meant to be, and it can be valuable when you want to, as the JsonStub home page says, “Fake the back end while you develop the front end.”



Mockable is another quick-and-dirty tool for mocking up REST and SOAP endpoints. The service’s base tier is free in perpetuity, although any routes not used within three months are deleted, logs are only retained for 24 hours or unless they exceed 5MB, and you’re only allowed to create up to 10 mockups per three-member team. Best part: You don’t even have to register to try it out. Temporary accounts are automatically created for you the minute you enter the admin console.



Httpbin.org provides you with an array of HTTP API endpoint responses that are useful for testing or debugging front ends that send requests. Instead of configuring the responses through a web interface, you configure them with URL parameters.

For example, the /links/:n endpoint allows you to request a webpage with n HTML links—as a way to test a web scraper, for instance. The whole project is also available as a Python package under an MIT-like license.



Little is more embarrassing than to have a public-facing API fall over dead the minute it goes live because you didn’t test how well it held up under heavy load. Set up a target host’s endpoint via Loader’s web interface or API, and test results will be delivered to you via a browser page in real time. The free version of the service allows you to test one target host for one minute at a time, with up to 10,000 simulated clients.



Like Loader, BlazeMeter is an API load-testing service that provides real-time reporting features, plus other goodies like geo-distributed load testing (you can have traffic generated from servers on multiple continents) and support for tests created by Apache JMeter.

Sign up, and you’re given a 14-day trial of the Pro version (normally $649 per month). After that, you’re on the feature-restricted free tier, where you’re limited to 50 concurrent users in tests, up to 10 tests, a maximum test duration of 20 minutes, and data retained from tests for only one week. You do, however, get to use BlazeMeter’s Selenium Webdriver test suite, albeit for only five concurrent (simulated) users.