ApiNotes vs Doxygen

ApiNotes turns OpenAPI and Swagger specifications into hosted interactive documentation and a changelog that alerts teams to breaking changes. It accepts OpenAPI 3.0, 3.1, and 3.2, plus Swagger 2.0, in YAML or JSON. Generated references show endpoint parameters, response schemas, code samples in more than 10 programming languages, and a Try-It-Now console. Users can paste, upload, or link a specification and publish documentation at an ApiNotes subdomain. A GitHub Action can publish an updated specification on merge, while the Team plan lists pull request comments about breaking changes. Starter is free and limited to one public API, the last 10 changelog releases, 25 subscribers, and one team member. Team costs $19 a month and includes five APIs, private docs, full changelog history, unlimited subscribers, a custom domain, and five team members. The Team plan has a 14-day trial with no credit card required. Additional APIs are listed at £5/API; Postman, Bruno, and Insomnia integrations are marked as coming soon.

Doxygen is a free documentation generator that turns source-code comments into reference material, parsing items such as classes, functions and variables. It supports C/C++, Lex, Java, Python, VHDL, PHP IDL, C#, Fortran, Objective-C 2.0 and some D sources. Output can be generated as HTML, PDF through LaTeX, Word through RTF or structured XML for external tools. Graphviz’s dot tool can add include-dependency, collaboration, call, directory-structure and class-hierarchy diagrams. Doxywizard provides a graphical interface for editing settings and running the generator on Windows, Linux and macOS; Doxygen also works on many Unix flavors. It supports HTML Help, docsets, Qt-Help and Eclipse Help, with more than 100 configurable options. The tool runs without registration and does not collect personal or usage data. It is self-hosted and licensed under the GNU General Public License, without express or implied warranty. Help is listed through Stack Overflow and the doxygen users mailing list; commercial feature and bug-fix support has limited capacity.