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APIs · head to head

KeystoneJS vs Stainless

KeystoneJS logo

KeystoneJS

APIs

Powerful Node.js headless CMS framework and API platform

From
Free
Rated
-
Full reviewWebsite
Stainless logo

Stainless

APIs

Generates client SDKs, API docs, and MCP servers from an OpenAPI spec

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: KeystoneJS database support is limited to PostgreSQL, MySQL and SQLite; Stainless starter and Pro plan prices are not published and require contacting the company.
  • They diverge on capability: KeystoneJS covers REST API, Stainless covers SDK generation.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which KeystoneJS and Stainless actually diverge.

Attributes where KeystoneJS and Stainless differ
AttributeKeystoneJSStainless
Pricing modelopen-sourcefreemium
PlatformsNode.js, Self-hostedweb, api
Founded2016Unknown

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

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 KeystoneJS

  • REST API
  • GraphQL API
  • Admin interface
  • Node.js
  • Next.js
  • React
  • Databases
  • Node.js support

Only in Stainless

  • SDK generation
  • MCP server generation
  • Docs site generation
  • Webhooks and streaming support
  • Automated unit tests
  • Git integration

What people use each for

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

KeystoneJS

  • Headless CMS implementationnot Stainless
  • Content management systemsnot Stainless
  • Customizable API-driven applicationsnot Stainless

Stainless

  • Generating typed SDKs for a public APInot KeystoneJS
  • Producing an MCP server from an existing OpenAPI specnot KeystoneJS
  • Building an API documentation site alongside client librariesnot KeystoneJS
  • Giving open-source APIs a free SDK generation pathnot KeystoneJS

Where each one falls short

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

KeystoneJS

  • Database support is limited to PostgreSQL, MySQL and SQLite
  • Keystone 5 is a separate legacy product documented on a different site and is not covered by the Keystone 6 docs
  • Upgrading requires following a dedicated Migrate to 8.0.0 guide, so major versions are not drop-in
  • Free support is a community Slack; enterprise-grade consulting and support is a separate paid engagement with Thinkmill and no published price

Stainless

  • Starter and Pro plan prices are not published and require contacting the company.
  • The free plan caps APIs at 25 endpoints, which excludes larger production APIs.
  • Overage charges apply per SDK/endpoint/month once limits are exceeded, which can make costs unpredictable at scale.

Pricing, plan by plan

KeystoneJS

Free
  • Open SourceFree
    • Full KeystoneJS
    • Community support

Stainless

Free
  • FreeFree
    • Up to 5 generators (SDKs, docs, or MCP servers)
    • 5 seats
    • APIs with 25 or fewer endpoints
  • Starter$undefined/mo
    • Unlimited generators
    • Expanded seats
    • Private SDKs of any size
  • Pro$undefined/mo
    • Custom enterprise features and pricing
  • Enterprise$undefined/mo
    • Dedicated support
    • SOC 2 compliance reports
    • Purchase order/invoicing with negotiable terms

Which should you pick?

Choose KeystoneJS if

  • You need rest api.
  • You want to start without paying.
  • You work on Node.js, Self-hosted.
  • You also want graphql api.
KeystoneJS review

Choose Stainless if

  • You need sdk generation.
  • You want to start without paying.
  • You work on web, api.
  • You also want mcp server generation.
Stainless review

Questions people ask

Is KeystoneJS or Stainless better?
Neither clearly leads. KeystoneJS starts at Free and Stainless at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, KeystoneJS or Stainless?
KeystoneJS starts at Free and Stainless at Free.
Does KeystoneJS or Stainless run on more platforms?
KeystoneJS runs on Node.js, Self-hosted. Stainless runs on web, api.
Can I use KeystoneJS for free?
Both have a free tier, so you can try either at no cost before committing.
What is KeystoneJS best used for?
KeystoneJS is most often used for headless cms implementation, content management systems, customizable api-driven applications. Of those, headless cms implementation and content management systems are not what Stainless is typically brought in for.
What can KeystoneJS do that Stainless cannot?
KeystoneJS covers REST API, GraphQL API, Admin interface, Node.js. Stainless covers SDK generation, MCP server generation, Docs site generation, Webhooks and streaming support.

Answered from the vendors’ own pages

KeystoneJS: Is KeystoneJS free?

Yes, KeystoneJS is free and open source with no licensing fees. Core platform has no lock-in and is contributed to by 250+ developers.

Source
Stainless: Is there a free plan, and what are its limits?

Yes. The Free plan supports up to 5 generators, 5 seats, APIs with 25 or fewer endpoints, and 100 preview builds per month, with email support.

Source
KeystoneJS: What are hosting costs for KeystoneJS?

KeystoneJS is self-hosted and deployment-agnostic. Hosting costs depend on your chosen deployment platform (Vercel, AWS, Heroku, etc.) and infrastructure, not KeystoneJS itself.

Source
Stainless: Who owns the generated SDK code?

The generated SDK code is owned by the customer and published by Stainless under the Apache 2.0 license.

Source
KeystoneJS: Does KeystoneJS offer paid support?

Enterprise support with tailored options is available from Thinkmill, the company behind KeystoneJS. Pricing details available upon request.

Source
Stainless: What happens if I exceed my plan's endpoint limit?

Customers exceeding their endpoint limits are billed per SDK, per endpoint, per month for the overage.

Source
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