Free and open first

Best API Documentation Tools in 2026

API documentation tools help present an API’s endpoints and supporting guidance for developers who need to understand or use an interface. Compared on interactive API reference, code samples, and OpenAPI import, the entries cover practical parts of documenting APIs. API versioning is another factor as interfaces change; custom domain and hosting model can help you assess how documentation fits your setup. Free plans and paid-from pricing offer cost context. Scalar, Doxygen, and Apiary are among the tools shown. Compare the listed capabilities with the documentation workflow and publishing approach you need.

27 apps
Research read 23 Sept 2026
How the order is worked out

1

Fern

Free plan Open source APILinuxMac+3

Fern combines API documentation publishing with client library generation and offers a defined Free plan.

9.1 Free plan Visit site
2

Scalar

Free plan Open source APILinuxMac+3

Scalar brings several API documentation and management tools together, with hosted and self-hosted options.

8.7 Free plan · paid from $150/mo Visit site
3

Javadoc

Free plan LinuxMacWeb+1

Javadoc provides standard HTML documentation generation alongside options for custom output. Review output safety and the terms that apply to later JDK updates.

7.5 30-day trial Visit site
4

Apiary

Free plan APIWeb

Apiary links API descriptions with mock responses, documentation, and automated response checks.

7.4 Free plan Visit site
5

Doxygen

Free plan LinuxMacWindows

Doxygen offers broad language and output-format coverage for code documentation, with a GUI and diagram support. Users should account for its warranty terms and limited commercial support capacity.

7.4 Free plan Visit site
6

DapperDox

Free plan LinuxSelf-hostedWeb+1

DapperDox offers a self-hosted route to combine OpenAPI reference material with explanatory documentation and an interactive explorer.

7.3 Open source Visit site
7

ApiNotes

Free plan Web

ApiNotes turns supported API specifications into hosted references with interactive features and breaking-change changelogs.

7.2 Free plan · paid from $19/mo · 14-day trial Visit site
8

Endrel

Free plan APIWeb

Endrel brings specification imports, drift review, and team collaboration into a hosted API documentation workspace.

7.2 Free plan · paid from ₹1,499/mo Visit site
9

phpDocumentor

Free plan LinuxMacSelf-hosted

phpDocumentor offers a free, self-hosted route to PHP API documentation, with diagrams, markup support, and CI options.

7.1 Open source Visit site
10

Mihari

Free plan Web

Mihari combines monitoring and operational visibility with a free tier and a listed €19 monthly platform plan. Review the free-tier limits and public beta status against your team's requirements.

7.0 Free plan · paid from €19/mo Visit site
11

pdoc

Free plan LinuxMacSelf-hosted+2

pdoc offers a direct route from Python modules and docstrings to navigable HTML API documentation. Consider its HTML-only output and dynamic analysis behavior before using it for a project.

7.0 Open source Visit site
12

Redocly
by Redocly
Free plan APIExtensionWeb

Redocly brings API references, collaboration, governance, and monitoring into one product set, with an open-source CLI and VS Code extension.

7.0 From $10/user/mo · 30-day trial Visit site
13

Theneo

Free plan APIExtensionSelf-hosted+1

Choose Theneo if you need API documentation with collaboration, supported API formats, and options for private customer portals.

7.0 Free plan · paid from $120/mo (annual) Visit site
14

JSDoc

Free plan APISelf-hosted

JSDoc provides a configurable, self-hosted route from JavaScript comments to HTML documentation.

6.9 Free plan Visit site
15

Miredot

Free plan Self-hosted

Miredot ties Java REST documentation to the build process and provides quality checks before release.

6.9 Free plan · 14-day trial Visit site
16

Palt

Free plan Web

Palt combines OpenAPI-based documentation publishing with endpoint testing, code examples, and visual editing.

6.9 Free plan · paid from $19/mo Visit site
17

RAML2HTML

Free plan LinuxSelf-hosted

Choose RAML2HTML if you need a free, self-hosted way to render RAML documentation and value command-line or library use.

6.9 Open source Visit site
18

RapiDoc

Free plan Self-hostedWeb

RapiDoc offers interactive documentation and substantial display customization for supported API specifications.

6.9 Free plan Visit site
19

OpenAPI 3 Generator

Free plan LinuxSelf-hosted

OpenAPI 3 Generator focuses on command-line generation from OpenAPI 3 inputs, with extensive template customization.

6.8 Open source Visit site
20

PilotDocs

Free plan Web

PilotDocs brings interactive references, guides, version management, and search together for hosted API documentation.

6.8 Free plan · paid from $49/mo · 14-day trial Visit site
21

Stoplight Elements

Free plan Self-hostedWeb

Stoplight Elements covers core interactive API documentation needs with OpenAPI support, code examples, and an embedded console.

6.8 Free plan Visit site
22

TypeDoc

Free plan APILinuxSelf-hosted

Choose TypeDoc if you need free generation of TypeScript documentation from code comments, with built-in HTML and JSON output and a plugin API.

6.8 Free plan Visit site
23

Widdershins

Free plan APILinuxSelf-hosted

Widdershins offers several API definition inputs and renderer-oriented outputs, with templates and samples users can adapt.

6.8 Open source Visit site
24

ReadMe
by ReadMe
Free plan Web

6.7 Free plan · paid from $250/mo (annual) · 14-day trial Visit site
25

Swagger2Markup

Free plan APILinuxSelf-hosted

Swagger2Markup provides configurable, self-hosted conversion from Swagger specifications into several documentation formats.

6.6 Open source Visit site

#1Places #1, #2, #3, #4, #5 on this list can be bought by the makers of the software on it. See the price

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