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Documentation · head to head

Outline vs Slab

Outline logo

Outline

Documentation

Team knowledge base under the Business Source Licence, self-hostable or vendor hosted

From
Free
Rated
-
Full reviewWebsite
Slab logo

Slab

Documentation

Internal knowledge base for teams, organised by topic rather than folders, with search across connected tools

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Outline the Business Source Licence is not an open source licence, so anyone planning to host Outline for clients, resell it or embed it in a commercial service is prohibited until the per-release change date passes, and this is regularly discovered only at legal review.; Slab it is built for internal knowledge, so public product documentation on a custom domain with versioning is outside what the product does.
  • They diverge on capability: Outline covers Structured collections, Slab covers Topics instead of folders.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which Outline and Slab actually diverge.

Attributes where Outline and Slab differ
AttributeOutlineSlab
Pricing modelFree to self-host, per user per month when hosted by the vendorPer user per month
PlatformsWeb, Self-hosted, Docker, iOS, AndroidWeb

Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated), category (Documentation).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Outline

  • Structured collections
  • Block editor
  • Search
  • Backlinks and mentions
  • Templates
  • API and webhooks
  • Single sign-on
  • Self-hosting

Only in Slab

  • Topics instead of folders
  • Unified search
  • Post verification
  • Quill editor
  • Permissions
  • Free tier for small teams

What people use each for

The jobs each tool is most often brought in to do.

Outline

  • Running an internal wiki on your own infrastructure when documentation cannot leave a specific jurisdictionnot Slab
  • Replacing a general-purpose workspace tool with something narrower where search speed and writing flow matter mostnot Slab
  • Keeping engineering decision records and postmortems in templated documents that link to each other automaticallynot Slab
  • Giving a company already standardised on Google or Okta a wiki that inherits identity and group membership directlynot Slab

Slab

  • Building an employee handbook and onboarding path that new starters can actually findnot Outline
  • Replacing a folder-based wiki where nobody agrees which folder a document belongs innot Outline
  • Companies whose knowledge is already spread across Drive, Slack and GitHub and needs one search boxnot Outline
  • Documenting process and decisions for teams that do not want a project management tool attachednot Outline

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Outline

  • The Business Source Licence is not an open source licence, so anyone planning to host Outline for clients, resell it or embed it in a commercial service is prohibited until the per-release change date passes, and this is regularly discovered only at legal review.
  • There is no local password authentication, so self-hosting requires an identity provider to be in place first, which turns a small internal wiki into a project with a dependency on Google, Okta, Entra or a Keycloak instance somebody has to run.
  • Self-hosting needs Postgres, Redis and S3-compatible object storage together, so the operational footprint is larger than the single database most internal wikis require.
  • The hosted plans offer no customer-selectable hosting region, so buyers with data residency obligations are pushed to self-hosting even when they would have paid to avoid running servers.
  • It is built for internal knowledge rather than public documentation, with no versioned documentation sets, no static output and limited public publishing, so it will not serve as a product documentation site.
  • Because it is a single-vendor project rather than a foundation-governed one, a future licence or pricing change applies to new releases and the only defence is staying on an older version.

Slab

  • It is built for internal knowledge, so public product documentation on a custom domain with versioning is outside what the product does.
  • There is no docs-as-code workflow, no git synchronisation and no markdown files on disk, so engineering-owned technical documentation ends up somewhere else anyway.
  • Hierarchy is shallow by design, and organisations that genuinely need deep nested structure find topics an awkward substitute rather than an improvement.
  • There is no offline mode, so a knowledge base that includes incident runbooks is unavailable during exactly the incident where the network is the problem.
  • Pricing is per user per month, so organisations where most staff only read a handbook twice a year still pay a seat for each of them.

Pricing, plan by plan

Outline

Free
  • Self-hostedFree
    • Source available under the Business Source Licence
    • No licence fee for use inside your own organisation
    • Requires Postgres, Redis and S3-compatible storage
  • Team (hosted)$undefined/month
    • Charged per user per month
    • Hosted and maintained by the vendor
    • Single sign-on through Google, Slack or Microsoft
  • Enterprise (hosted)$undefined/month
    • SAML single sign-on and provisioning
    • Administrative controls and audit visibility
    • Negotiated terms and support

Slab

Free
  • FreeFree
    • Up to ten users
    • Unlimited posts
    • Core integrations
  • Slab$undefined/month
    • Priced per user per month with annual billing
    • Unlimited users and history
    • Full integration set and unified search

Which should you pick?

Choose Outline if

  • You need structured collections.
  • You want to start without paying.
  • You work on Web, Self-hosted, Docker, iOS, Android.
  • You also want block editor.
Outline review

Choose Slab if

  • You need topics instead of folders.
  • You want to start without paying.
  • You also want unified search.
Slab review

Questions people ask

Is Outline or Slab better?
Neither clearly leads. Outline starts at Free and Slab at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Outline or Slab?
Outline starts at Free and Slab at Free.
Does Outline or Slab run on more platforms?
Outline runs on Web, Self-hosted, Docker, iOS, Android. Slab runs on Web.
Can I use Outline for free?
Both have a free tier, so you can try either at no cost before committing.
What is Outline best used for?
Outline is most often used for running an internal wiki on your own infrastructure when documentation cannot leave a specific jurisdiction, replacing a general-purpose workspace tool with something narrower where search speed and writing flow matter most, keeping engineering decision records and postmortems in templated documents that link to each other automatically, giving a company already standardised on google or okta a wiki that inherits identity and group membership directly. Of those, running an internal wiki on your own infrastructure when documentation cannot leave a specific jurisdiction and replacing a general-purpose workspace tool with something narrower where search speed and writing flow matter most are not what Slab is typically brought in for.
What can Outline do that Slab cannot?
Outline covers Structured collections, Block editor, Search, Backlinks and mentions. Slab covers Topics instead of folders, Unified search, Post verification, Quill editor.

Answered from the vendors’ own pages

Outline: Is Outline open source?

No, not in the OSI sense. It is source available under the Business Source Licence, which permits internal use and self-hosting but not offering it as a service to others, with each release converting to an open source licence after its change date.

Slab: Can I publish documentation publicly with Slab?

Posts can be shared by link, but it is not a product documentation platform. There is no custom domain publishing, versioning or API reference tooling.

Outline: Can I run it for free?

Yes, for your own organisation. Self-hosting carries no licence fee, only the cost of running Postgres, Redis, object storage and an identity provider.

Slab: What does the free plan actually cover?

Up to ten users with unlimited posts and core integrations. It is a real free tier rather than a trial, and it is enough for a small company handbook.

Outline: Can I choose where the hosted version stores data?

No. The hosted plans do not offer a region choice, so residency requirements mean self-hosting.

Slab: How does it compare with a general workspace tool?

Slab does less on purpose. There are no databases, boards or task views, which makes it faster to write in and much harder to turn into an unmaintained sprawl.

Outline: Does it work for public product documentation?

Poorly. It has no versioned documentation sets or static site output, so it is best kept for internal knowledge.

Slab: Does search really cover other tools?

Yes, connected sources are indexed and appear in results. That integration is the main reason to choose it, so verify your specific tools are supported before committing.

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