SwaggerHub is an integrated API design and documentation platform, built for teams to drive consistency and discipline across the API development workflow. It is built by the creators of the popular Swagger open source tooling, and allows teams to develop APIs faster on a centralized platform.
Gelato was recently acquired by Mashape and is available as an on-premise option as well as a SaaS offering. It is free to use for open-source projects and has an Enterprise edition available for large scale applications. Pricing for Enterprise edition hasn't been disclosed by Gelato.API Documentation Solutions Gelato