OpenAPI Generator - OpenAPI Generator enables you to generate documentation, clients, and servers from OpenAPI 2.0/3.x documents without hassle.
Doxygen - Generate documentation from source code
Swagger Codegen - Swagger Codegen can reduce the complexities that arise in your build process by providing client SDKs and server stubs for any API you want.
Docsify.js - A magical documentation site generator.
API Transformer - API Transformer is a powerful solution that enables you to Transform API specifications to any format.
GitBook - Modern Publishing, Simply taking your books from ideas to finished, polished books.