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Developer Tools · head to head

Backstage vs Kotlin Multiplatform

Backstage logo

Backstage

Developer Tools

Open source internal developer portal framework created and open sourced by Spotify

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: Backstage backstage is a framework rather than a product: there is no supported turnkey install, so getting to a usable portal means a TypeScript and React project your team owns, hosts and upgrades forever.; 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: Backstage covers Software catalogue, 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 Backstage and Kotlin Multiplatform actually diverge.

Attributes where Backstage and Kotlin Multiplatform differ
AttributeBackstageKotlin Multiplatform
PlatformsWeb, Self-hosted, Linux, Docker, KubernetesiOS, Android, Windows, macOS, Linux, Web
CategoryDeveloper ToolsMobile Development

Identical on both: starting price (Free), pricing model (Open source, no licence fee), 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 Backstage

  • Software catalogue
  • Software templates
  • TechDocs
  • Plugin architecture
  • Kubernetes plugin
  • Search
  • Entity ownership model
  • Auth provider integrations

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.

Backstage

  • An engineering organisation past roughly a hundred services where nobody can reliably answer who owns a given service at two in the morningnot Kotlin Multiplatform
  • A platform team enforcing golden paths, so a new service is scaffolded with logging, CI and security defaults already wired innot Kotlin Multiplatform
  • A company consolidating scattered READMEs and Confluence pages into docs that live beside the code and cannot silently rot unnoticednot Kotlin Multiplatform
  • A regulated business that needs an auditable register of every running service, its owner and its data classificationnot Kotlin Multiplatform

Kotlin Multiplatform

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

Where each one falls short

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

Backstage

  • Backstage is a framework rather than a product: there is no supported turnkey install, so getting to a usable portal means a TypeScript and React project your team owns, hosts and upgrades forever.
  • Upstream releases move quickly and plugin APIs have broken across major versions, so a customised deployment accumulates upgrade debt and teams routinely fall months behind on versions they cannot cheaply catch up on.
  • The catalogue is only as good as the YAML descriptors engineers remember to write; without enforcement the register drifts out of date, and a developer portal nobody trusts is abandoned faster than one that never existed.
  • Community plugin quality varies sharply, with many unmaintained or pinned to old core versions, so the plugin that made the business case may be the one blocking your next upgrade.
  • Spotify Portal, the packaged commercial route, publishes no price at all and is quoted as a custom annual subscription, so the only cost you can actually forecast up front is the self-hosted one, which is the option with the largest hidden staffing bill.

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

Backstage

Free
  • Backstage (open source)Free
    • Apache 2.0 licence
    • Software catalogue, templates, TechDocs and search
    • Full plugin ecosystem
  • Spotify Portal for Backstage$undefined/year
    • Packaged commercial distribution from Spotify
    • Spotify premium plugins including Soundcheck and Insights
    • Simplified setup and managed upgrade path

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 Backstage if

  • You need software catalogue.
  • You want to start without paying.
  • You work on Web, Self-hosted, Linux, Docker, Kubernetes.
  • You also want software templates.
Backstage 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 Backstage or Kotlin Multiplatform better?
Neither clearly leads. Backstage 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, Backstage or Kotlin Multiplatform?
Backstage starts at Free and Kotlin Multiplatform at Free.
Does Backstage or Kotlin Multiplatform run on more platforms?
Backstage runs on Web, Self-hosted, Linux, Docker, Kubernetes. Kotlin Multiplatform runs on iOS, Android, Windows, macOS, Linux, Web.
Can I use Backstage for free?
Both have a free tier, so you can try either at no cost before committing.
What is Backstage best used for?
Backstage is most often used for an engineering organisation past roughly a hundred services where nobody can reliably answer who owns a given service at two in the morning, a platform team enforcing golden paths, so a new service is scaffolded with logging, ci and security defaults already wired in, a company consolidating scattered readmes and confluence pages into docs that live beside the code and cannot silently rot unnoticed, a regulated business that needs an auditable register of every running service, its owner and its data classification. Of those, an engineering organisation past roughly a hundred services where nobody can reliably answer who owns a given service at two in the morning and a platform team enforcing golden paths, so a new service is scaffolded with logging, ci and security defaults already wired in are not what Kotlin Multiplatform is typically brought in for.
What can Backstage do that Kotlin Multiplatform cannot?
Backstage covers Software catalogue, Software templates, TechDocs, Plugin architecture. Kotlin Multiplatform covers Shared Kotlin logic, Native UI retained, Compose Multiplatform (optional), IDE tooling.

Answered from the vendors’ own pages

Backstage: Is Backstage free?

The project is Apache 2.0 with no licence fee. The real cost is engineering time; teams commonly dedicate one to two engineers permanently to running it.

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.

Backstage: Do I need to write code to use it?

Yes. Configuring and extending a Backstage application is a TypeScript and React project. This is the single most common misjudgement buyers make.

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.

Backstage: What is Spotify Portal for Backstage?

A commercial distribution from Spotify with premium plugins and support, generally available since October 2025 and sold as a quoted annual subscription with no published price.

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.

Backstage: Who owns the project?

Spotify created and open sourced it; it is now a CNCF project, so the upstream roadmap is not solely Spotify controlled.

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