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Documentation · head to head

Outline vs Scalar

Outline logo

Outline

Documentation

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

From
Free
Rated
-
Full reviewWebsite
Scalar logo

Scalar

Documentation

Open source API reference renderer and request client generated entirely from an OpenAPI document

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.; Scalar it documents only what an OpenAPI document can express, so guides, authentication walkthroughs and conceptual pages need a second tool and a second navigation.
  • They diverge on capability: Outline covers Structured collections, Scalar covers OpenAPI driven reference.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which Outline and Scalar actually diverge.

Attributes where Outline and Scalar differ
AttributeOutlineScalar
Pricing modelFree to self-host, per user per month when hosted by the vendorOpen source, no licence fee
PlatformsWeb, Self-hosted, Docker, iOS, AndroidWeb, macOS, Windows, Linux

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 Scalar

  • OpenAPI driven reference
  • Embedded API client
  • Generated code samples
  • Framework adapters
  • Themeable renderer
  • Self hostable
  • Spec validation

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 Scalar
  • Replacing a general-purpose workspace tool with something narrower where search speed and writing flow matter mostnot Scalar
  • Keeping engineering decision records and postmortems in templated documents that link to each other automaticallynot Scalar
  • Giving a company already standardised on Google or Okta a wiki that inherits identity and group membership directlynot Scalar

Scalar

  • Replacing default Swagger UI on a public API without moving to a hosted documentation vendornot Outline
  • A framework that already emits an OpenAPI document and needs a reference page mounted on a routenot Outline
  • An internal API portal that must run inside a private network with no external callsnot Outline
  • A team that wants readers to make authenticated test calls without leaving the reference pagenot 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.

Scalar

  • It documents only what an OpenAPI document can express, so guides, authentication walkthroughs and conceptual pages need a second tool and a second navigation.
  • The output is only as good as the spec, so an API with thin descriptions and missing examples produces a thin reference and the tool cannot compensate.
  • Deep visual customisation goes beyond the theme variables quickly, and matching an existing brand often means overriding styles against internal class names that can change.
  • Running the embedded client against a production API invites readers to send real requests, which means rate limits, test accounts and CORS configuration become your problem.
  • The open source renderer and the hosted platform advance at different rates, so a feature seen in a demo is not necessarily in the package you self host.

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

Scalar

Free
  • Open source rendererFree
    • MIT licence, no fee for the renderer
    • Embedded request client
    • Framework adapters

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 Scalar if

  • You need openapi driven reference.
  • You want to start without paying.
  • You work on Web, macOS, Windows, Linux.
  • You also want embedded api client.
Scalar review

Questions people ask

Is Outline or Scalar better?
Neither clearly leads. Outline starts at Free and Scalar at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Outline or Scalar?
Outline starts at Free and Scalar at Free.
Does Outline or Scalar run on more platforms?
Outline runs on Web, Self-hosted, Docker, iOS, Android. Scalar runs on Web, macOS, Windows, Linux.
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 Scalar is typically brought in for.
What can Outline do that Scalar cannot?
Outline covers Structured collections, Block editor, Search, Backlinks and mentions. Scalar covers OpenAPI driven reference, Embedded API client, Generated code samples, Framework adapters.

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.

Scalar: Can I use it without paying anything?

Yes. The renderer is open source and self hostable. The hosted platform is a separate paid product.

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.

Scalar: Does it replace a full documentation site?

No. It covers API reference. Guides and concepts need a general documentation generator alongside it.

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.

Scalar: Will my reference go out of date?

Only if your OpenAPI document does. The reference is generated, so there is no second copy to forget.

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.

Scalar: Does the embedded client send real requests?

Yes, from the reader browser. Plan for CORS, rate limits and a sandbox environment before publishing.

Scalar: What if my API has no OpenAPI document?

Then this is the wrong tool. Producing an accurate spec is the prerequisite, not an optional step.

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