Best Tools For Generating Free API Documentation — OpenAPI, Zudoku, Scalar, Redoc
When building documentation for your modern APIs, we rarely start from scratch. Instead, most of us will generate API descriptions from API contracts defined in the OpenAPI format.
To get started we have to find all available tools and compare them against our unique needs. This post is a starting point for this journey. Here's our pick of the best free API documentation tools around today.
1. Zudoku
Zudoku is created by Zuplo and claims that API documentation should be free. Zudoku offers modern API Documentation based on OpenAPI and MDX. The big benefit of Zudoku is that it is the only modern documentation platform that not only renders API documentation from your OpenAPI file but it also provides support for any MDX files so that you can also render free-form documentation—a feature that other providers offer only in their paid plans.
Zudoku is best for: Companies looking for modern full-featured documentation without AI capabilities.
Pros:
- Free: The tool is completely free and open-source
- API Documentation & free-form documentation
- Mobile support
2. Scalar
The company behind the Scalar API docs is gaining attention lately. It describes itself as
The modern open-source developer experience platform for your APIs.
In addition to various API tools their offering contains a React library that renders OpenAPI files into Documentation. Unfortunately, this offering does not include free-form documentation and meta pages.
Scalar is best for: Companies looking for modern API-only documentation without AI capabilities.
Pros:
- Free: The tool is completely free and open-source
- API Documentation
- Mobile support
3. Swagger UI
Link to the Swagger UI Website
Swagger UI is an open-source offering from the company behind the OpenAPI standard, SmartBear.
It offers an interface that many developers are familiar with and offers stellar support for all OpenAPI features.
Swagger UI is best for: Companies looking for traditional API documentation without AI capabilities and meta pages.
Pros:
- Free: The tool is completely free and open-source
- API Documentation
- Mobile support
4. ReDoc
Link to the Redoc Github Repository
Like Scalar and Swagger UI, Redoc is a tool to render API documentation from OpenAPI files. The company behind it, Redocly is currently rebranding and about to launch more extensive API tooling. Redoc has been around for a long time and is deployed by many companies. It offers stellar support for all OpenAPI features as well as mobile support.
Redoc is best for: Companies looking for traditional API documentation without AI capabilities and meta pages.
Pros:
- Free: The tool is completely free and open-source
- API Documentation
- Mobile support
Final Thoughts
Today's API ecosystem is fast-moving and robust. We have great free & open-source options available to us when building our API documentation, moving the bar for paid offerings. If you are looking for a way to manage and connect your OpenAPI file to the documentation providers above, try API-Fiddle. Connect any workspace to your GitHub documentation repository to sync your OpenAPI with your OpenAPI docs.
We were fed up with unclear API definitions and bad APIs
So we created a better way. API-Fiddle is an API design tool with first-class support for DTOs, versioning, serialization, suggested response codes, and much more.