Three wikis can hold a team's documentation on your own server, and the first thing that sets them apart is how they file pages. BookStack makes you use shelves, books and chapters, Outline puts documents in collections and nests them inside one another, and Wiki.js builds its tree from each page's path. Outline is the only one with simultaneous editing in a stable release, but it has no local accounts, and its licence, BSL 1.1, is not open source. Wiki.js straddles two versions: a stable 2.x, and a 3.0 beta that requires PostgreSQL and can't be upgraded in place.
Shelves, collections or paths: how each wiki files its pages
BookStack stores content on four fixed levels: pages, optionally grouped into chapters, inside books, which shelves then collect, and one book can sit on several shelves. Dan Brown, its creator, chose these levels on purpose and wrote in December 2023 that he had no intent to add more. The README calls BookStack an "opinionated" platform where basic word-processing skills should be enough to write. The structure can still be reworked: since v22.06 a chapter converts into a book and a book into a shelf. Permissions follow the same levels. A role gets rights on a shelf, a book, a chapter or a page; book and chapter permissions cascade to their content, shelf permissions don't.
Outline, which describes itself as a knowledge base for growing teams, puts every document in a collection, and a document can hold other documents.
Wiki.js never asks you to create a folder or a book. Each page lives at a path such as /infra/backups, and the tree is inferred from those paths. Permissions work the same way: each group pairs global rights with rules that match an exact path, a prefix, a suffix or a regular expression, so one group can read /clients and never see /hr.
The editor, and writing together
BookStack offers a visual editor built on TinyMCE and a Markdown editor that keeps the source in the database next to the rendered HTML; diagrams are drawn in diagrams.net, embedded in the editor. BookStack has no simultaneous editing. The request dates back to 2017, and in February 2026 the maintainer said the move to a new Lexical-based editor was made with it in mind, though he was still working out how to merge edits in PHP. That editor is still in beta as of v26.09.
Outline is built for writing together: a dedicated collaboration service merges edits in real time, and comments sit inline in the text. Its editor is keyboard-first, with Markdown shortcuts, / commands and [[ to mention another document.
Wiki.js lets you pick the editor page by page: Markdown, AsciiDoc, raw HTML or a visual editor, and since 2.5.201 the Convert action moves a page from one to another. Its Git module pushes pages to a remote repository and pulls back whatever changed there, so a page fixed in a code editor and pushed to the repository comes back into the wiki. Simultaneous editing, with other writers' cursors, only arrives with 3.0, which is still in beta.
Local accounts, a directory, or a mandatory identity provider
Outline has no sign-up form and no passwords. People sign in through Google, Slack, Microsoft Entra, Discord or an OpenID Connect provider, and its .env.sample file warns that at least one is required, or the login page will offer nothing. The emailed sign-in link and passkeys only work for people who are already members. A team that uses none of those four services has to run its own OIDC provider, and the self-hosted SSO comparison covers several. SAML, which BookStack and Wiki.js include at no cost, needs Outline's paid Business + Enterprise licence.
BookStack and Wiki.js start with local accounts, email and password, and can also plug into a company directory. BookStack supports LDAP, SAML 2.0 and OpenID Connect, plus sign-in through Google, GitHub, GitLab, Slack, Discord or AzureAD, among others. With OIDC, email login goes away and the provider's groups map to roles by name. Wiki.js handles LDAP, SAML, CAS, Okta, Azure AD, and generic OAuth2 or OpenID Connect. Both offer two-factor authentication: through a TOTP app in BookStack, and on the modules that support it in Wiki.js.
What each tool needs to run
Read from the repositories and documentation on 7 October 2026.
| Tool | Licence | What you run | Structure | Sign-in | Latest release |
|---|---|---|---|---|---|
| BookStack | MIT | PHP 8.2 with twelve extensions, Composer, a web server, MySQL 8.0 or MariaDB 10.6; memory not documented | shelves, books, chapters, pages | local accounts, LDAP, SAML 2.0, OIDC | v26.09.1, 29 Sep 2026 |
| Outline | BSL 1.1, not open source | Node.js, PostgreSQL 14 and Redis 4 or later, a dedicated domain; at least 512 MB of RAM | collections, nested documents | external provider required; SAML paid | 1.10.1, 9 Sep 2026 |
| Wiki.js | AGPL-3.0 | 2.x: Node.js 22 or 24, PostgreSQL advised, MySQL, MariaDB, SQL Server or SQLite accepted; 3.0: Node.js 26 and PostgreSQL 16 to 18; 1 GB of RAM, a dedicated domain | tree inferred from page paths | local accounts, LDAP, SAML, CAS, OAuth2, OIDC | 2.5.316, 2 Oct 2026; 3.0.0-beta.628, 4 Oct 2026 |
BookStack is the only one of the three without an official Docker image: the official install is a Git checkout or a script for Ubuntu, the LinuxServer.io and solidnerd images are community-maintained, and shared PHP hosting is not supported. Its docs name no database other than MySQL and MariaDB. Outline and Wiki.js each want a dedicated domain or subdomain, and the Wiki.js docs state that a subfolder such as /wiki/ will not be supported. Outline asks for at least 512 MB of memory, and 1 GB or more as the user count grows; Wiki.js sets a 1 GB minimum on Linux and recommends two cores, in 2.x and 3.0 alike. Outline keeps attachments on disk or in S3-compatible storage and runs full-text search inside PostgreSQL, with no search engine alongside; Wiki.js's default search also queries the database.
Where the projects stand
BookStack has shipped releases since January 2016, now numbered by year and month. Three feature releases came out in 2026 and five in 2025, and 13 of the 22 releases since January are security releases; v26.05.4 closed, among other things, a remote code execution path through ZIP import. The project warns that feature releases are more likely to break an install: since v26.09, an instance without an APP_KEY throws an error. Development moved from GitHub to Codeberg in April 2026.
Outline has published releases since 2018 but only left the 0.x series with 1.0.0, on 26 October 2025. Nine minor releases followed in 2026, about one a month, up to 1.10.1 on 9 September.
Wiki.js has maintained its 2.5 branch since September 2020 and shipped eight releases of it in 2026. They now come out of a separate repository, requarks/wiki-v2, described as the maintenance version, while the main repository carries 3.0: ten pre-releases between the first alpha on 30 August 2026 and the beta of 4 October, all marked "NOT FOR PRODUCTION USE". Neither the website nor the docs give a date for the final release. Moving from 2.x to 3.0 means exporting a .wkbackup package and importing it into a fresh instance; module settings don't carry over, so Git sync and SSO have to be set up again.
Each of the three rests on one main developer. Dan Brown has 4,714 commits on BookStack's GitHub mirror against 126 for the next contributor; tommoor has 7,265 in Outline's repository against 936; NGPixel has 2,157 in Wiki.js's against 14.
Moving off Confluence
BookStack and Outline both pitch themselves as Confluence alternatives, each on a page of its website, yet none of the three, self-hosted, can import a Confluence space for free today. BookStack's page says as much: there is no automated way yet to bring the content over, and the REST API can only automate part of the job. Outline can import a Confluence space from its HTML export, but self-hosted, that importer belongs to the Business + Enterprise licence: in the public code, the Confluence entry on the import page only shows a disabled "Enterprise" button. Wiki.js 3.0 lists an import from Confluence among its admin utilities, with a disabled button marked "Coming soon"; the 2.x code has no such import.
Licences and paid plans
BookStack is under MIT, with no paid edition and no hosted offering, which its FAQ rules out. Donations and sponsorships cover about half the funding and support plans at £450 or £4,500 a year the rest, with no feature held back for paying customers. Wiki.js is under AGPL-3.0: a modified instance that people use over a network has to offer them its source code. Its website shows no paid offering and credits the project to its sponsors and backers.
Outline is under BSL 1.1, and its licence text states that it is not an open source licence. Any use is allowed except running a "Document Service": a commercial offering where third parties, other than your employees and contractors, create teams and documents of their own. Each version switches to Apache 2.0 no later than four years after release, which for 1.10.1 means 9 September 2030. Self-hosted, the Business + Enterprise licence, with no public price, adds SAML, the security audit log, structured data attributes and the Confluence importer. In the cloud, Starter costs 10 dollars a month for up to 10 members, and SSO and groups start at Team, 79 dollars a month for 11 to 100 members.