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APIs · head to head

KeystoneJS vs Kotlin Multiplatform

KeystoneJS logo

KeystoneJS

APIs

Powerful Node.js headless CMS framework and API platform

From
Free
Rated
-
Full reviewWebsite
Kotlin Multiplatform logo

Kotlin Multiplatform

Mobile Development

JetBrains-funded technology for sharing Kotlin business logic across iOS, Android, web, desktop and server

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: KeystoneJS database support is limited to PostgreSQL, MySQL and SQLite; Kotlin Multiplatform it shares logic, not UI, by default, so a team expecting a Flutter-style single UI codebase has to also adopt Compose Multiplatform, which is newer and less proven on iOS than on Android.
  • They diverge on capability: KeystoneJS covers REST API, Kotlin Multiplatform covers Shared Kotlin logic.
  • Prices and features above were last checked on 1 September 2026.

Where they differ

Only the attributes on which KeystoneJS and Kotlin Multiplatform actually diverge.

Attributes where KeystoneJS and Kotlin Multiplatform differ
AttributeKeystoneJSKotlin Multiplatform
Pricing modelopen-sourceOpen source, no licence fee
PlatformsNode.js, Self-hostediOS, Android, Windows, macOS, Linux, Web
CategoryAPIsMobile Development
Founded2016Unknown

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

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 Kotlin Multiplatform

  • Shared Kotlin logic
  • Native UI retained
  • Compose Multiplatform (optional)
  • IDE tooling
  • Gradle-based builds
  • Incremental adoption

What people use each for

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

KeystoneJS

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

Kotlin Multiplatform

  • A company with existing separate native iOS and Android codebases wanting to stop duplicating business logic and networking codenot KeystoneJS
  • A team that wants shared logic but is not willing to compromise on fully native UI per platformnot KeystoneJS
  • An organisation already using Kotlin on the backend that wants to reuse the same models and validation on mobile clientsnot KeystoneJS
  • A team evaluating Compose Multiplatform for UI sharing but wanting the option to fall back to native UI per screennot 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

Kotlin Multiplatform

  • It shares logic, not UI, by default, so a team expecting a Flutter-style single UI codebase has to also adopt Compose Multiplatform, which is newer and less proven on iOS than on Android.
  • iOS interop relies on Kotlin/Native compiling to a framework consumed from Swift, and debugging across that boundary is more friction than debugging pure Swift or pure Kotlin.
  • Because logic-sharing is the whole premise, teams still need genuine iOS and Android UI expertise on staff; it does not reduce the native skills bar the way a full cross-platform UI framework aims to.
  • Build times and tooling maturity for multiplatform Gradle projects lag behind single-platform Kotlin or Swift projects, and multiplatform-specific build errors are less well documented.
  • JetBrains funds it as part of the broader Kotlin investment, so its roadmap priority competes internally with IntelliJ, Android Studio and other JetBrains commitments rather than having dedicated headcount the way Flutter has at Google.

Pricing, plan by plan

KeystoneJS

Free
  • Open SourceFree
    • Full KeystoneJS
    • Community support

Kotlin Multiplatform

Free
  • Kotlin MultiplatformFree
    • Apache 2.0 licensed, unlimited apps
    • IDE tooling in the free Android Studio and free-tier IntelliJ IDEA Community
    • No paid Kotlin Multiplatform edition exists

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 Kotlin Multiplatform if

  • You need shared kotlin logic.
  • You want to start without paying.
  • You work on iOS, Android, Windows, macOS, Linux, Web.
  • You also want native ui retained.
Kotlin Multiplatform review

Questions people ask

Is KeystoneJS or Kotlin Multiplatform better?
Neither clearly leads. KeystoneJS starts at Free and Kotlin Multiplatform at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, KeystoneJS or Kotlin Multiplatform?
KeystoneJS starts at Free and Kotlin Multiplatform at Free.
Does KeystoneJS or Kotlin Multiplatform run on more platforms?
KeystoneJS runs on Node.js, Self-hosted. Kotlin Multiplatform runs on iOS, Android, Windows, macOS, Linux, Web.
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 Kotlin Multiplatform is typically brought in for.
What can KeystoneJS do that Kotlin Multiplatform cannot?
KeystoneJS covers REST API, GraphQL API, Admin interface, Node.js. Kotlin Multiplatform covers Shared Kotlin logic, Native UI retained, Compose Multiplatform (optional), IDE tooling.

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
Kotlin Multiplatform: Does Kotlin Multiplatform replace my native UI code?

Not by default. It shares business logic and data layers; UI stays native per platform unless you separately adopt Compose Multiplatform.

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
Kotlin Multiplatform: Is there a paid version?

No. It is Apache 2.0 licensed and free, funded by JetBrains as part of the Kotlin project.

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
Kotlin Multiplatform: Do I need Compose Multiplatform to use it?

No, they are separate. You can share only logic and keep fully native UI on each platform indefinitely.

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