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Developer Tools · head to head

PartyKit vs Sardine

P

PartyKit

Developer Tools

Platform for building and deploying realtime multiplayer servers on the edge

From
Free
Free plan
Yes
Full reviewWebsite
Sardine logo

Sardine

Cybersecurity

Device intelligence and behaviour biometrics for fraud and compliance

From
On request
Free plan
No
Full reviewWebsite

The short version

  • Only PartyKit has a free tier, so it costs nothing to try first.
  • Each has a real cost: PartyKit documentation and FAQ material on the marketing site is sparse compared to larger realtime platforms.; Sardine signal quality depends on the SDK being embedded in your own web and mobile clients, so fraud improvements become dependent on your app release cycle and any coverage gap is a blind spot.
  • They diverge on capability: PartyKit covers Stateful edge servers, Sardine covers Device intelligence.
  • Prices and features above were last checked on 1 September 2026.

Where they differ

Only the attributes on which PartyKit and Sardine actually diverge.

Attributes where PartyKit and Sardine differ
AttributePartyKitSardine
Starting priceFreeOn request
Pricing modelfreemiumquote
Free tierYesNo
Platformsweb, apiWeb, iOS, Android
CategoryDeveloper ToolsCybersecurity

Identical on both: 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 PartyKit

  • Stateful edge servers
  • WebSocket-first API
  • CRDT library compatibility
  • Framework integrations
  • Global edge deployment
  • Custom domains

Only in Sardine

  • Device intelligence
  • Behaviour biometrics
  • Scam detection
  • Onboarding risk scoring
  • AML transaction monitoring
  • Dispute and chargeback handling
  • Rules editor

What people use each for

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

PartyKit

  • Multiplayer collaborative appsnot Sardine
  • Realtime AI agent backendsnot Sardine
  • Live cursors and presencenot Sardine
  • Collaborative whiteboards and documentsnot Sardine

Sardine

  • A neobank losing money to authorised push payment scams where the customer genuinely approved the transfernot PartyKit
  • A crypto exchange trying to detect accounts being operated by remote access rather than by their ownernot PartyKit
  • A fintech seeing synthetic identity signups that pass document verification but share device characteristicsnot PartyKit
  • A lender wanting first party fraud signals at application time that a credit bureau file does not containnot PartyKit

Where each one falls short

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

PartyKit

  • Documentation and FAQ material on the marketing site is sparse compared to larger realtime platforms.
  • Commercial free tier requires deploying to the user's own Cloudflare account, adding setup complexity.
  • Storage on the free Individual plan clears every 24 hours, limiting it to prototyping rather than persistent production data.
  • Smaller ecosystem and community than more established realtime infrastructure providers.

Sardine

  • Signal quality depends on the SDK being embedded in your own web and mobile clients, so fraud improvements become dependent on your app release cycle and any coverage gap is a blind spot.
  • Behavioural and device telemetry collection needs a documented lawful basis under GDPR, and EU privacy reviews frequently delay rollouts that were scoped as engineering work.
  • Pricing is per session or per active user, so a consumer product with many low value sessions pays in proportion to traffic rather than to fraud exposure.
  • As a younger private company it lacks the enforcement-tested audit history that a bank examiner expects, which makes it a harder sell inside a regulated bank than inside a fintech.
  • It is strongest on session-time signals and weaker as a system of record for long horizon AML typologies, so larger institutions end up running it alongside a traditional monitoring platform rather than instead of one.

Pricing, plan by plan

PartyKit

Free
  • IndividualFree
    • Up to 10 live projects
    • Deploy to the global edge platform
    • Storage clears every 24 hours
  • CommercialFree
    • Unlimited projects
    • Custom domains
    • Runs on your own Cloudflare account; pay only Cloudflare usage

Sardine

On request
  • Sardine$undefined/year
    • Priced per user session or per monthly active user
    • Annual contract with volume commitment
    • SDK for web, iOS and Android

Which should you pick?

Choose PartyKit if

  • You need stateful edge servers.
  • You want to start without paying.
  • You work on web, api.
  • You also want websocket-first api.
PartyKit review

Choose Sardine if

  • You need device intelligence.
  • You work on Web, iOS, Android.
  • You also want behaviour biometrics.
Sardine review

Questions people ask

Is PartyKit or Sardine better?
Neither clearly leads. PartyKit starts at Free and Sardine at On request, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, PartyKit or Sardine?
PartyKit has a free tier; the other does not. Paid plans start at Free for PartyKit and On request for Sardine.
Does PartyKit or Sardine run on more platforms?
PartyKit runs on web, api. Sardine runs on Web, iOS, Android.
Can I use PartyKit for free?
Yes. PartyKit has a free tier, so you can try it without paying. Sardine starts at On request.
What is PartyKit best used for?
PartyKit is most often used for multiplayer collaborative apps, realtime ai agent backends, live cursors and presence, collaborative whiteboards and documents. Of those, multiplayer collaborative apps and realtime ai agent backends are not what Sardine is typically brought in for.
What can PartyKit do that Sardine cannot?
PartyKit covers Stateful edge servers, WebSocket-first API, CRDT library compatibility, Framework integrations. Sardine covers Device intelligence, Behaviour biometrics, Scam detection, Onboarding risk scoring.

Answered from the vendors’ own pages

PartyKit: How much does PartyKit cost?

PartyKit is completely free. Both the Individual and Commercial plans have no upfront costs.

Source
Sardine: Does Sardine do document verification?

It focuses on device, behavioural and transaction signals, and integrates identity verification providers rather than being one. Treat it as complementary to a KYC vendor.

PartyKit: What is PartyKit's Individual plan?

The Individual plan is free and includes deployment to a global edge platform, support for up to 10 live projects, and is suitable for small projects. Storage is cleared every 24 hours.

Source
Sardine: What does it need from us to work?

An SDK in your web and mobile applications plus transaction feeds. Without the client side collector you lose the signals that differentiate it.

PartyKit: What is PartyKit's Commercial plan?

The Commercial plan is free but requires deploying to your own Cloudflare account. It includes custom domains, unlimited projects, and you pay only your Cloudflare usage costs.

Source
Sardine: Is pricing published?

No. It is quoted, typically per session or per monthly active user with an annual volume commitment.

PartyKit: Can I upgrade from Individual to Commercial plan?

Yes, both plans are free but offer different feature sets. The Commercial plan removes project restrictions but requires managing your own Cloudflare infrastructure.

Source
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