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Comparison · Infra & APIs

Ably vs Fission

A side-by-side editorial comparison of Ably and Fission — release velocity, themes, recent moves, and the top alternatives to consider.

Ably vs Fission: at a glance

FeatureAblyFission
SectorInfra & APIsInfra & APIs
Velocity score6.30.0
Sparks · 30d10
Top themesrealtime-infrastructure, ai-agents, durable-execution, liveobjectsserverless, kubernetes, faas, release-candidates
Last editorial update19h ago2h ago
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What is Ably?

Ably is building an agent transport layer on its realtime core, shipping AI SDK versions every ten days.

Two release trains run side by side in this feed. The AI Transport SDK is moving fast and pre-1.0 — durable execution in 0.5.0, mid-run steering in 0.6.0, an OpenAI Responses codec in 0.7.0, each roughly ten days apart and each carrying breaking changes. The Pub/Sub and Java SDKs move at a steadier pace, working through LiveObjects reach, React and React Native support, and now connectivity fallbacks.

Read the full Ably trajectory →

What is Fission?

Fission's release feed carries only RC tags, and none of them say what shipped

Every entry here is a release candidate — v1.22.0-rc1 and rc2, v1.23.0-rc1, v1.25.0-rc1 — with no final release appearing between them, and the version sequence skips 1.24 entirely. The bodies are whatever the tagging commit said, so what reaches this feed is a dependabot bump, a CLI tool-version refresh, a codegen sync explicitly labelled as having no functional change, and one entry that is nothing but links to an external release-highlights page. The actual release notes live on the project's documentation site, not here.

Read the full Fission trajectory →

Ably vs Fission: editorial side-by-side

A
Ably
INFRA · APIS
6.3

Ably is building an agent transport layer on its realtime core, shipping AI SDK versions every ten days.

◆ Current state

Two release trains run side by side in this feed. The AI Transport SDK is moving fast and pre-1.0 — durable execution in 0.5.0, mid-run steering in 0.6.0, an OpenAI Responses codec in 0.7.0, each roughly ten days apart and each carrying breaking changes. The Pub/Sub and Java SDKs move at a steadier pace, working through LiveObjects reach, React and React Native support, and now connectivity fallbacks.

◆ Where it's heading

Ably is treating agent conversations as a transport problem — sessions, resumability, and multi-client reconciliation — rather than as a model-integration problem, and the primitives shipping in AI Transport keep pointing that way. The Pub/Sub line is being pulled along behind it: LiveObjects path APIs and React hooks are the state layer those agent sessions need. The pre-1.0 SDK will keep breaking as the shape settles, which is a reasonable trade while the category is unsettled.

◆ Prediction

Expect AI Transport to keep adding provider codecs beyond OpenAI Responses and to approach an API freeze as breaking changes get more expensive. LiveObjects support should continue spreading across the language SDKs, following the Java path-based API with other platforms.

F
Fission
INFRA · APIS
0.0

Fission's release feed carries only RC tags, and none of them say what shipped

◆ Current state

Every entry here is a release candidate — v1.22.0-rc1 and rc2, v1.23.0-rc1, v1.25.0-rc1 — with no final release appearing between them, and the version sequence skips 1.24 entirely. The bodies are whatever the tagging commit said, so what reaches this feed is a dependabot bump, a CLI tool-version refresh, a codegen sync explicitly labelled as having no functional change, and one entry that is nothing but links to an external release-highlights page. The actual release notes live on the project's documentation site, not here.

◆ Where it's heading

What can be read from these tags is infrastructure maintenance rather than product direction: Go dependency updates, helm and kind and skaffold and cosign version refreshes, and regenerated swagger and applyconfiguration files kept in sync with CEL and webhook validation comments in the core API types. That last one is the only entry hinting at anything structural — CEL-based validation on the API types implies declarative validation moving into the CRDs — but the commit itself changes only generated output.

◆ Prediction

This feed does not carry enough to predict product direction; until final releases or their notes appear here rather than only candidate tags, any read of where Fission is heading would be guesswork.

Alternatives to Ably and Fission

Other Infra & APIs products tracked by Sparkpulse, ranked by recent ship velocity. Each card links to a full editorial trajectory and lets you pivot into a head-to-head comparison with either Ably or Fission.

See all Ably alternatives → · See all Fission alternatives →

Recent activity from Ably and Fission

Latest ship moves from both products, interleaved chronologically. ⚡ = editorial spark.

  1. 22h agoAblyPub/Sub JS SDK v2.27.0: Fallback for networks that block WebSockets
  2. 10d agoAblyAI Transport JS SDK v0.7.0: OpenAI Responses codec
  3. 18d agoAblyPub/Sub JS SDK v2.26.0: React hook for LiveObjects
  4. 21d agoAblyAI Transport JS SDK v0.6.0: Mid-run steering
  5. 24d agoAblyPub/Sub JS SDK v2.25.0: Push notifications for React Native
  6. 28d agoAblyJava SDK v1.8.0: Support LiveObjects Path based API
  7. 2mo agoFissionFission 1.25.0-rc1 tag carries only regenerated codegen output
  8. 2mo agoFissionFission 1.23.0-rc1 tag carries a CI tool-version refresh
  9. 7mo agoFissionv1.22.0-rc2
  10. 9mo agoFissionFission 1.22.0-rc1 tag carries a golang.org/x/net bump

Frequently asked questions

What is the difference between Ably and Fission?

They serve adjacent needs but don't currently overlap on shipped themes. Ably is currently shipping more aggressively (velocity 6.3 vs 0.0), with 1 editorial sparks in the last 30 days against 0. See the at-a-glance table above for a side-by-side breakdown of velocity, recent sparks, and editorial themes.

Is Ably better than Fission?

Sparkpulse doesn't pick a winner — we score release velocity, not feature parity. Ably is currently shipping more aggressively (velocity 6.3 vs 0.0), with 1 editorial sparks in the last 30 days against 0. For your specific use case, the alternatives sections above list other Infra & APIs products to evaluate alongside.

What are the best alternatives to Ably?

Top Ably alternatives in Infra & APIs are ranked by recent ship velocity. Browse the "Ably alternatives" section above for the current picks, or visit /alternatives/ably for the full list with editorial commentary on each.

What are the best alternatives to Fission?

Top Fission alternatives in Infra & APIs are ranked by recent ship velocity. Browse the "Fission alternatives" section above for the current picks, or visit /alternatives/fission for the full list with editorial commentary on each.