This list includes documentation authoring tools designed as Content Management Systems (CMS), including their subtypes such as Component Content Management System (CCMS), headless CMS and others.

Paligo is a cloud-based Component Content Management System (CCMS) with powerful single-sourcing content reuse for technical documentation, training content, policies and procedures, and efficient knowledge management. Paligo offers a number of content reuse options, powerful structured authoring and multiple channels for content publishing.
Website: paligo.net

Document360 is an AI-powered knowledge base software for creating and sharing self-service knowledge bases. It offers a range of tools, including documentation creation, categorization, editing, and branding features such as markdown support, version control with rollback options, preview capabilities, AI-driven search, custom domain mapping, internal commenting, and other functionalities.
Website: document360.com

ReadMe, even though advertised as a developer-oriented API documentation CMS, also allows users to create and publish documentation websites that cover both end-user and developer documentation. ReadMe adds interactivity to API documentation, by allowing users to test API examples interactively and allowing documentation authors and other internal stakeholders to get detailed metrics related to their API usage through docs.
Website: readme.com

Archbee is a documentation platform that allows you to create and share private or public documentation. It provides an effective and efficient way to create and manage multiple knowledge bases that are easily accessible to both employees and customers. In addtion, Archbee offers collaboration options, third party integrations with tools such as GitHub, Slack, Jira or import and sync for OpenAPI files.
Website: archbee.com

GitBook allows you to collaborate, publish and maintain technical knowledge in a single, centralized knowledge base. The content can be accessed and edited using text or code, with GitHub and GitLab integrations that enable two-way sync with a Git branch where changes to one are automatically reflected in the other one. Collaboration is also branch-based, while there is also a number of integrations to extend the native functionality of GitBook.
Website: gitbook.com
ClickHelp is an online documentation tool for technical writers and teams that allows users to create, publish, and translate documentation in one portal. It offers documentation portal white labelling, more than 20 integrations, cloud hosting for both the content and the authoring environment, multiple projects and project versions in a single portal, multi-channel publishing and a host of other features.
Website: clickhelp.com