#1★ TOP PICK
BookStack
Shelves, books, chapters, pages — a wiki organised like a library.
94
OPEN SOURCEMITSELF-HOSTLOCAL-FIRST
BookStack borrows its structure from a bookshelf, and that one decision is why people stick with it: content has an obvious home instead of drifting into a flat page soup. It is PHP and MySQL, installs in an afternoon, has a WYSIWYG and a Markdown editor, and does full-text search properly. MIT licensed, around 19k stars, actively developed. For a team that wants documentation to be findable a year later, the structure matters more than any feature list.
Strengths
- +Shelf/book/chapter/page structure keeps documentation findable at scale
- +MIT with no enterprise edition and no feature gate
- +Genuinely light — runs well on hardware you would not consider adequate
- +Simple PHP/MySQL stack most sysadmins already know
Trade-offs
- −No Jira integration worth the name
- −Editor is competent rather than delightful
- −Real-time collaborative editing is weaker than Confluence's
- −You own backups, updates and uptime
Free and open source. A small VPS runs it comfortably. #2
Wiki.js
Every editor, every auth provider, every storage backend.
92
OPEN SOURCEAGPL-3.0SELF-HOSTLOCAL-FIRST
Wiki.js is the flexible one: Markdown, WYSIWYG, HTML and AsciiDoc editors, more than fifty authentication providers, and content that can sync to Git so your wiki has real version history in a repository you control. AGPL-3.0, around 29k stars. That Git sync is the feature worth noticing — it makes documentation reviewable in pull requests, which is how engineering teams already work. The trade is configuration: it does a great deal, and it asks you to decide about most of it.
Strengths
- +Git storage backend gives real version control over documentation
- +Over fifty auth providers — SSO into almost anything
- +Multiple editors, so writers are not forced into one style
- +Mature, with years of production use
Trade-offs
- −More configuration than BookStack before it feels finished
- −Node and a database to operate
- −Version 3 has been a long time coming
- −Search is adequate rather than excellent
Free and open source. You supply the server and database. #3
XWiki
The heavyweight — a wiki you can program like an application platform.
91
OPEN SOURCELGPL-2.1SELF-HOSTLOCAL-FIRST
XWiki has been running enterprise documentation for two decades and is less a wiki than a platform you write applications on top of: structured data, scripting, forms and workflow all live inside the wiki itself. LGPL-2.1, Java, with a large extension marketplace. It is the only option here that genuinely replaces Confluence Data Center feature for feature, including the parts organisations use for regulated processes. It is also the heaviest, and it looks its age next to Docmost.
Strengths
- +The only true Confluence Data Center replacement, feature for feature
- +Structured data and scripting — build applications inside the wiki
- +Two decades of enterprise deployment behind it
- +LGPL with commercial support available
Trade-offs
- −Heaviest option here — a Java application to operate
- −Interface is dated next to the newer tools
- −Steep learning curve for the platform features
- −Overkill if you just want to write pages
Free and open source. Commercial support available from XWiki SAS. #4
Docmost
The modern one — real-time collaborative editing, Notion-like feel.
90
OPEN SOURCEAGPL-3.0SELF-HOSTLOCAL-FIRST
Docmost is the newest serious entrant and feels it: block-based editor, real-time collaboration, nested pages, comments and diagrams, with the polish people expect after using Notion. AGPL-3.0, around 21k stars and moving quickly. It is the closest thing here to the editing experience that makes people reluctant to leave Confluence. The caveat is age — it has the shortest production track record on this page, and AGPL is strong copyleft worth reading if you intend to modify it.
Strengths
- +Best editing experience of the open options — genuinely modern
- +Real-time collaborative editing works properly
- +Nested pages, comments, diagrams and permissions built in
- +Fast-moving project with real momentum
Trade-offs
- −Youngest project here; shortest production history
- −AGPL-3.0 copyleft needs reading before you modify it
- −Smaller community than BookStack or Wiki.js
- −Some enterprise features sit in the paid tier
Free and open source to self-host. A paid cloud tier exists. #5
Outline
The best-looking option — and not open source, whatever the lists say.
66
SOURCE-AVAILABLEBusiness Source License 1.1 (source-available, not OSI open source)SELF-HOSTLOCAL-FIRST
Outline is a fast, beautifully judged team knowledge base with excellent search, a slash-command editor and Slack integration that people actually use. It is also the entry on this page most often mislabelled. Outline ships under the **Business Source License 1.1**, not an OSI licence: you may self-host it for internal use, but you may not offer it as a competing hosted service, and the licence converts to open source only after a delay. For most companies documenting their own work that changes nothing. If you were planning to build a product on it, it changes everything — and you would not learn that from the directory that told you it was open source.
Strengths
- +Best design and editing experience of anything on this page
- +Search is genuinely fast and good
- +Slack and API integrations that people use daily
- +Self-hostable for ordinary internal use
Trade-offs
- −NOT open source — Business Source License, despite near-universal mislabelling
- −Cannot be offered as a competing hosted service
- −Licence terms can be tightened by the vendor on future versions
- −Smaller plugin ecosystem than Confluence
Self-hostable free within BUSL terms. Outline Cloud is paid per user.