# Cohesivity vs Ably

Ably: “Durable sessions for apps and AI agents.”

Ably does realtime, and it does it seriously: pub/sub that survives dropped connections, chat, presence, live sync, and a transport built specifically for agent sessions that need to stay durable. When a message absolutely has to arrive and the connection cannot be trusted, this is the kind of platform you reach for, and you build against it after signing up.

Cohesivity is not a realtime specialist. It provisions a realtime service, channels, presence, and WebSocket messaging, as one line in a backend that also has a database, storage, auth, and AI, all stood up by your coding agent with no account. The project runs for 72 hours, then you claim it. So Ably is deeper at realtime by a wide margin. Cohesivity's edge is only that realtime comes with the backend and needs no signup.

side by side

## Cohesivity and Ably, on the points that differ

__Comparison of Cohesivity and Ably__
|                | Cohesivity                                                                 | Ably                                                                     |
| -------------- | -------------------------------------------------------------------------- | ------------------------------------------------------------------------ |
| what it is     | A whole backend with realtime as one of its services.                      | A dedicated, durable realtime and messaging platform.                    |
| realtime depth | Channels, presence, WebSocket messaging, HTTP publish and history.         | Durable pub/sub, chat, presence, live sync, and agent-session transport. |
| signup         | None. The agent provisions realtime with the backend, then you claim it.   | Create an Ably account to build against it.                              |
| who it is for  | Agent-built apps that want live updates alongside the rest of the backend. | Apps where durable, at-scale realtime is a core requirement.             |
| billing        | Free $0, Plus $20, Pro $100, one shared balance.                           | A free tier, then usage-based paid plans.                                |

where Cohesivity fits

- Realtime without a separate platform. The agent provisions channels and presence with the rest of the backend, so there is no Ably account to set up first.
- One backend, not another vendor. Realtime arrives next to the database, storage, auth and AI from the same API, with the keys managed for you.
- Enough realtime to ship. If live updates, presence, and simple messaging cover your app, the agent provisions that as part of the build.

when Ably is the better call

Pick Ably if realtime is the hard part. Guaranteed delivery over unreliable connections, durable sessions, and presence at large scale are exactly what it is engineered for, and a bundled realtime service does not match that depth.

Pick Ably if you are building chat, collaboration, or agent sessions where dropped messages are unacceptable. Its transport and delivery guarantees are the reason it exists.

This is a depth call. Ably is the specialist and goes far beyond what Cohesivity offers on realtime. Cohesivity only makes sense here when your realtime needs are ordinary and you would rather they came free with the backend.

questions

### Is Cohesivity an Ably alternative?

Only for simpler realtime. Cohesivity provisions channels, presence, and messaging as one service in a no-signup backend. Ably is a dedicated realtime platform with durable delivery and agent-session transport that goes well beyond what Cohesivity offers on realtime alone.

### What realtime does Cohesivity provide?

A realtime service with channels, presence, WebSocket messaging, and HTTP publish and history, provisioned by the agent as part of the backend. It covers common live-update needs rather than Ably's full durability guarantees.

### Do I need an Ably-style account to start?

No. Cohesivity provisions realtime with the backend and no signup, and you claim the project later. Ably requires an account to build against it.

### Can Cohesivity guarantee delivery like Ably?

Ably is built specifically around durable, guaranteed delivery over unreliable connections. Cohesivity offers standard realtime messaging as part of a backend, not Ably's depth of delivery guarantees. For strict durability, Ably is the stronger tool.

related comparisons

Ably details verified 2026-07-22 from ably.com, including its apps-and-agents realtime positioning. Cohesivity details from its own docs. Features and pricing change, so check current terms with each provider.

Try it against Ably.

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