Ably vs Centrifugo
Discover how Centrifugo compares to Ably, and understand which is right for your use case, based on dimensions such as core features, pricing, reliability, and scalability.
What is Ably?
Ably is a realtime infrastructure platform that provides APIs and SDKs to power live experiences at global scale, with no infrastructure to build or maintain. Ably’s products include:
- Pub/Sub: Managed WebSocket messaging at scale, with guaranteed ordering, exactly-once delivery, and connection recovery out of the box
- Chat, Spaces, and LiveSync: Purpose-built SDKs for common realtime use cases
- AI Transport: Resumable streaming and session continuity for AI applications
What is Centrifugo?
Centrifugo is an open source, language-agnostic, self-hosted pub/sub server capable of scalable realtime messaging. It uses transports like WebSockets to deliver messages to active users.
Compare Ably and Centrifugo
The biggest difference between Ably and Centrifugo is who runs the infrastructure, and what’s guaranteed as a result. With Centrifugo, your team deploys, scales, and staffs on-call for the servers, and builds any guarantees it needs on top. Ably is a managed platform: it runs the infrastructure and publishes its delivery, ordering, and uptime commitments. That difference shows up in production: a client reconnecting after a long gap, a traffic spike, a regional outage, or an AI response that has to get through all of them. The quick answers below cover the most common evaluation questions. The full feature comparison follows.
Common evaluation questions
How do Ably and Centrifugo handle messages when a client disconnects and reconnects?
Centrifugo’s delivery is at most once by default. With history and recovery turned on, a reconnecting client can catch up, but only if three things hold:
- It returns inside the history window you configure.
- It missed no more than 300 messages (the default per recovery attempt).
- The history survived the disconnect.
Outside those limits, Centrifugo returns recovered: false, and your application has to reload state from its own database. If a client reconnects to Ably within two minutes, Ably replays every missed message in order with exactly-once semantics. This is on by default, and clients that are away longer can fetch what they missed from the history API.
How do Ably and Centrifugo compare on delivery and ordering guarantees?
Centrifugo doesn’t offer exactly-once delivery in either its open-source or PRO edition. Recovery can occasionally redeliver a message, so your application has to handle deduplication. Its ordering guarantee only holds when you publish to a channel sequentially, and concurrent publishes carry no ordering guarantee. Ably offers exactly-once delivery through idempotent publishing and connection recovery, and each publisher’s messages on a realtime connection arrive in order at every subscriber. With Ably, both are built into the platform, ready for your application to use.
How do Ably and Centrifugo compare on uptime and global distribution?
A Centrifugo cluster runs in whichever region you deploy it to, and its uptime depends on how your team runs it. Staying up through a regional outage takes a globally distributed system: clusters in several regions, kept in sync, with failover your team builds and tests. Ably is a globally distributed system across 12 regions that routes around regional incidents automatically, so service continues. It offers a 99.999% uptime SLA on Business and Enterprise plans, and has gone more than seven years without a global outage.
How do Ably and Centrifugo compare on latency?
With Centrifugo, latency depends on your deployment: where your cluster runs relative to your users, how its nodes and broker are sized, and how they behave under load. Centrifugo’s documentation doesn’t state a latency target, because your team runs the infrastructure it depends on. A cluster also runs in the region you deploy it to, so users far from it get higher latency unless you build a globally distributed system around it. Ably routes each client through 750+ edge locations to its nearest region, and publishes two latency figures: 6.5ms message delivery latency within a region, measured at the edge of Ably’s network, and a 37ms global median round-trip latency, measured from real browsers.
How do Ably and Centrifugo handle scaling and capacity?
Centrifugo scales horizontally: you add nodes behind a shared broker such as Redis or NATS, and provision that capacity yourself, by hand or with autoscaling you configure and maintain. Its FAQ gives a ballpark of 50,000 to 100,000 connections per node and recommends load-testing your own setup. Connections stay on the node they joined and aren’t moved when you add nodes, so a node that fills up during a traffic peak or mass reconnect stays overloaded. That means you need enough nodes in place for your peak connection volume before it arrives. As traffic grows, a single broker can become the bottleneck, and fixing it means moving to Redis Cluster or splitting channels across brokers under live traffic. Ably’s infrastructure scales on demand, with headroom provisioned above current demand and capacity added automatically as load rises, so Ably handles traffic spikes for you.
How does Centrifugo PRO compare with Ably?
Centrifugo PRO adds push notifications, realtime analytics, user and channel tracing, rate limiting, SSO for the admin UI, and prioritized support. Its pricing isn’t published, and it doesn’t guarantee a support response time. You still run the broker and the nodes, and on-call, capacity planning, patching, and upgrades stay with your team. Ably includes push notifications on its published plans, and Ably runs the infrastructure underneath them, backed by stated delivery and uptime commitments.
Is Centrifugo cheaper than Ably?
Centrifugo’s open-source license is free, but running it in production isn’t. Your team operates the broker (typically Redis or NATS) and a cluster of Centrifugo nodes, patches them, and staffs the on-call rotation that keeps them up. Google’s SRE guidance sizes that rotation at a minimum of eight engineers for 24/7 cover. That operational load carries real risk: in Ably’s 2022 survey of 500+ engineering leaders, 65% of teams building their own realtime infrastructure had an outage in the past 12–18 months. Ably’s pricing is published, starting at $29/month, with exactly-once delivery and ordering built in. A 99.999% uptime SLA is available on Business and Enterprise plans. So the real comparison is between a subscription and that operational risk.
How do I migrate from Centrifugo to Ably?
Mostly by adapting what you already have. Presence, channel history, server-key and client-token auth, and automatic reconnection all work in similar ways on both. The work is in Centrifugo-specific behavior:
- Permission checks your Centrifugo proxies make on each subscribe or publish move into Ably token issuance.
- Logic built on Centrifugo’s custom disconnect codes is rebuilt against Ably’s connection states.
- Code tied to your history window or the 300-message recovery limit is updated for Ably’s two-minute catch-up and history API.
Most teams move one channel or workload at a time, with both systems running until behavior is confirmed.
Full feature comparison table
Let’s compare Ably and Centrifugo, looking at key dimensions such as their core features, pricing, integrations & interoperability, quality of service, performance & availability and security & compliance.
| Core features | |||
Pub/Sub messaging | Reduces communication code complexity, simplifying the process of building highly functional and architecturally complex realtime apps. | Ably | Centrifugo Yes |
Chat capabilities | Accelerates the time to implement rich chat experiences with features such as read receipts, typing indicators, and more. | Ably Yes Ably Chat supports 1:1, group messaging and live streaming chat, with APIs for edit & delete, message and room reactions, moderation, typing indicators, moderation and more. Learn more about Ably Chat | Centrifugo Yes |
Collaboration capabilities | Enables you to quickly integrate realtime collaborative features like live cursors, member location, avatar stacks, and component locking. | Ably Yes The Spaces SDK provides an opinionated set of abstractions for collaborative environments including live cursors, avatar stacks and component locking. Learn more | Centrifugo No |
State sync capabilities | Enables realtime data synchronization across devices and users, ensuring a cohesive and up-to-date user experience. | Ably Yes Ably provides a self-hostable and managed database connector to stream updates over our serverless WebSocket platform. LiveSync provides seamless connector interactions for Postgres and MongoDB. Learn more | Centrifugo Yes |
Presence | Maintaining a view of which users are connected, and their associated metadata, enables their online status to be updated in realtime. | Ably Yes Ably’s presence API automatically syncs the full membership state on channel attach, ensuring clients always have an up-to-date and consistent view of who’s online. Learn more | Centrifugo Yes Read more |
Occupancy | High-level metrics about the clients currently connected to a channel make it simple to show things such as connected user count, or display which channels are the most popular. | Ably Yes Ably’s Occupancy API delivers detailed, real-time metrics (connections, publishers, subscribers, presenceMembers, etc.) for every channel as part of its built-in monitoring capabilities. Learn more | Centrifugo Yes |
Message interactions | Enables interaction with previously-sent messages, facilitating the implementation of features like message reactions and threads. | Ably Yes Ably’s annotations API lets you attach, update and aggregate metadata (reactions, flags, tags) to previously-sent messages and query the roll-up summary efficiently. Learn more | Centrifugo No |
Message history | Enables clients to catch up on missed messages when inactive, ensuring a user doesn’t miss any important messages. | Ably Yes | Centrifugo |
Push notifications | Cross-platform push notifications make it possible to deliver important and timely messages to users even when they’re inactive. | Ably Yes Support for Android and iOS push notifications. Improved web-push for browsers currently in progress. | Centrifugo |
Message delta compression | Minimizes bandwidth and can reduce latency, particularly in scenarios where continuous updates are sent. | Ably Yes The delta option sends only the change (via VCDIFF) from the previous message on a channel. See Deltas docs | Centrifugo Yes Centrifugo supports delta compression only in channels with recovery and positioning on. Read more |
Programmatic management | Enables the automation of provisioning, management, and testing of service resources, simplifying integration with existing development workflows such as CI. | Ably Yes Control API and a Terraform provider manage apps, keys, and channel rules as infrastructure. See Control API docs | Centrifugo Yes |
Server-side batching | Reduces the overall message count, lowers costs, and mitigates the risk of hitting rate limits during high-throughput scenarios. | Ably Yes Messages within a configurable interval group into one batch (up to 200 per batch), billed as one message. Not deduplicated by ID. See Batching docs | |
Maximum message size | A message size limit below your payload size means custom chunking on both publisher and subscriber, plus manual ordering logic — significant engineering overhead for LLM responses, document content, or structured data. | Ably 64 KiB on Free and Standard; 256 KiB on Pro and Enterprise. | |
AI streaming support | Without purpose-built AI streaming infrastructure, ordering, chunking, and session recovery have to be built and maintained across the stack - and they tend to fail at the moments users notice most. | Ably Yes Ably AI Transport provides resumable token streaming, multi-device session continuity, guaranteed ordered delivery, and two-minute session recovery for AI applications. | |
| Pricing | |||
Free plan | With a free plan, you can test the service’s functionality and compatibility with your project before committing to a paid plan. | Ably Yes Up to 500 monthly active users (MAUs), with full access to every Ably product and protocol. No credit card required. | Centrifugo Yes Centrifugo is open-source and free to use. |
Pricing model | The pricing model should align with your project's expected load, usage patterns, and budget in order to be cost-effective and efficient. | Ably Pay for the number of monthly active users (MAUs) using your application. | Centrifugo Centrifugo's base product is free and open-source, but there is also a paid version called Centrifugo PRO. Read more |
Pricing plans | The pricing plans offered by cost. | Ably Every package includes every Ably product. Prices billed annually are discounted, so you effectively get 2 months free:
Bespoke pricing is available from Pro upwards, invoiced on an annual commitment. Learn more | Centrifugo
|
| Integrations & interoperability | |||
SDKs | Supporting multiple languages and platforms offers greater flexibility when building cross-platform realtime apps. | Ably
| Centrifugo
|
Supported realtime protocols | Support for multiple protocols provides the flexibility to choose a protocol that best suits your project’s requirements. | Ably
| Centrifugo
|
Serverless functions | Enables integration with third-party cloud providers by facilitating the execution of custom code against messages to perform business logic like on-the-fly translation. | Ably
| Centrifugo None. |
Streaming & queueing | Provides a dependable method to reroute messages from the service to third-party streams and queues for further processing. | Ably Egress:
Ingress:
The Database Connector is designed for any database in the SQL-family, but at the moment only supports Postgres. Please contact us if you want support in other databases. | Centrifugo Yes |
Observability services | Enables realtime monitoring and troubleshooting by offering insights into service behavior directly in your observability platform of choice. | Ably Yes | Centrifugo Partial Centrifugo has no native observability tools, but offers integrations with monitoring tools such as Prometheus and Grafana. Read more |
CI/CD tools | Makes it possible to provision and configure service infrastructure as part of a CI or CD pipeline, enabling repeatable and reliable deployments. | Ably
| Centrifugo No Self-hosted, so you will have to implement your own. |
| Quality of Service | |||
Proven scalability | Scalability is vital as it ensures the service can handle increased data load or users without compromising performance. | Ably | Centrifugo Centrifugo is designed for high scalability; its Redis engine allows for scaling Centrifugo nodes to different machines. For specific stats on scale, you can read more in Centrifugo's scale test tutorial. |
Guaranteed message delivery | Ensures messages are never lost during transmission, even in the presence of network disruptions. | Ably Yes Guaranteed within a 2-minute reconnect window (full replay, in order). Beyond that, recoverable via History for the plan's retention period. See History docs | Centrifugo No |
Guaranteed message ordering | Maintains the sequence of messages as they were sent. This is particularly important in apps where the chronological order of messages is essential for meaningful communication. | Ably Yes Per publisher per channel - via message serials.:ctaSee message ordering docs: | Centrifugo Partial Centrifugo supports ordering in channels but not across channels. |
Exactly-once message delivery | Guarantees that each message is processed exactly once, preventing data inconsistencies that can arise from duplicate processing or missing messages. | Ably Yes | Centrifugo No |
Connection state recovery | Without connection state recovery, filling a disconnection gap requires a custom message store, fetch-on-reconnect logic, and deduplication - engineering the platform should handle natively. | Ably Yes If a client reconnects within two minutes, all missed messages are replayed in order with exactly-once semantics. No custom catch-up logic required. Beyond that, History covers 1 day (Free) up to unlimited (Enterprise). | |
| Performance & availability | |||
Uptime Guarantee | An uptime guarantee instills confidence in the reliability of the service and protects your business from the negative impacts of downtime. | Ably Yes 99.999% uptime SLA on Business and Enterprise plans. 7+ years without a global outage. See pricing and plans | Centrifugo N/A |
Global edge network | By bringing servers (Points of Presence, or PoP) geographically closer to the devices of end users, and routing requests to the nearest PoP, global latency is reduced to a minimum. | Ably Yes 12 globally distributed regions, 750+ edge locations through AWS CloudFront. See the edge network | Centrifugo No |
Multi-region data replication (message durability) | By replicating data across multiple regions, the risk of data loss or downtime is greatly mitigated since if data is lost or a server fails in one region, the information can be retrieved from another. | Ably Yes Messages replicate across 3+ physically isolated locations before acknowledgment; designed for 99.999999% message survivability. See the Ably architecture overview | Centrifugo No |
No single point of failure or congestion | Having no single point of failure means a system is resilient and can continue to operate even if one part fails. Avoiding a single point of congestion ensures messages flow efficiently across the system and avoids bottlenecks that could lead to performance issues under load. | Ably Yes | Centrifugo No Centrifugo relies on external systems like Redis or NATS for data storage, which may have their own failure points. |
Low latency | Low latency is crucial for realtime apps as it ensures swift and efficient data transmissions, providing a smoother and more responsive user experience. | Ably | Centrifugo N/A (self-hosted) |
| Security & compliance | |||
API key authentication | Simplifies the authentication code on trusted servers compared to requesting, managing, and refreshing tokens. | Ably Yes | Centrifugo Yes |
Token-based authentication | Provides a means to securely authenticate user devices against your user management system. | Ably Yes | Centrifugo |
Single Sign-On (SSO) authentication | SSO streamlines login processes, boosts security by minimizing password use, and meets compliance needs for secure data access management. | Ably Yes Google/GitHub sign-in on every plan. Full SAML SSO with any identity provider, plus SCIM, is Enterprise-only. See more in our SSO docs | Centrifugo |
Rules for permissions and operations | Provides control over which users can subscribe and publish to certain channels. | Ably Yes Capabilities scoped per key or token control subscribe, publish, and presence access down to channel-name patterns. | Centrifugo Yes Centrifugo supports permission rules for operations through its configuration. |
End-to-end encryption | Ensures that the data transmitted between the client and the API server remains confidential and secure while in transit. | Ably Yes TLS by default for all traffic. True end-to-end encryption (AES-256, opt-in per channel) is available via the cipher option. Learn more about Ably's encryption | Centrifugo No |
Encryption at rest | Ensures data stored by the service is secure and compliant, while also mitigating the risks of a data breach. | Ably Yes | Centrifugo No |
Compliance | Compliance with regulations can impact your ability to meet legal obligations in your industry. | Ably
Ably also offers EU and US-only data storage. | Centrifugo None |
Disclaimer: This comparison was created based on documentation and resources freely available online about Ably and Centrifugo. The content was last updated on 10 Jul 2026 for Ably and on 25 Sept 2025 for Centrifugo. Be sure to double-check everything before you make any decisions. If you do find anything incorrect or out of date, then please let us know.
Where Ably and Centrifugo diverge in production
These three scenarios show where the differences surface: not during integration, but at the moments that test the infrastructure. A long reconnect on a busy channel. A traffic spike. A regional outage.
Group chat with reconnecting mobile clients
A user in a busy group chat loses signal on a train for 90 seconds.
On Centrifugo, that gap is only filled if history is turned on for the channel, the client returns inside the history window your team configured, and no more than 300 messages were published in the meantime, which is the default recovery limit. If the channel was busy, Centrifugo returns recovered: false, and unless your app reloads from its own database, the user misses messages without knowing. On Ably, every message sent during the gap is delivered in order when the client reconnects within two minutes, automatically. If the client is away for longer, your app can fetch what it missed from Ably’s message history.
Live event with a sudden traffic spike
A sports app streams a live final, and connections triple in the minutes before kick-off.
On Centrifugo, that capacity has to be in place before the spike. Connections stay on the node they joined and aren’t moved when nodes are added, so nodes that fill up early stay overloaded, and a single broker can become the bottleneck. Getting it wrong means slow delivery and dropped connections at the moment your audience is largest. On Ably, the platform scales on demand, with headroom above current demand. For an especially large event, your account manager can work with you ahead of time, so you go into it with even more confidence.
A regional cloud outage
A cloud provider has an incident in the region where your realtime layer runs.
A Centrifugo cluster runs in the region you deploy it to, so the outage takes your realtime features down with it, unless your team has built and tested a globally distributed system with clusters in other regions. On Ably, regional incidents are routed around automatically across 12 globally distributed regions, so service continues. Ably has gone more than seven years without a global outage.
Is Ably or Centrifugo better suited for AI applications?
An AI response streamed to a UI needs every token delivered, in order, even when the connection drops. Both platforms can stream LLM tokens to a client over a channel. The differences show up when a stream is fast or interrupted, which is when users are most likely to see missing or duplicated tokens.
| Constraint | Centrifugo | Ably |
|---|---|---|
| Session recovery | Only if history is on and the gap fits the recovery limits. With one message per token, a fast stream can pass the 300-message default in seconds. | If the client reconnects within two minutes, every missed token is replayed automatically, with the history API for longer gaps. |
| Duplicates | Recovery can occasionally redeliver a message, so your application handles deduplication. | Exactly-once delivery through idempotent publishing and connection recovery, for clients that reconnect within two minutes. |
| Infrastructure | Your team runs the nodes and broker the stream depends on, through every traffic peak. | Ably runs the infrastructure and scales it on demand. |
Ably AI Transport adds resumable token streaming and multi-device session continuity on top, as a drop-in layer.
When to use each platform
| Centrifugo is appropriate when… | Ably is a better fit when… |
|---|---|
| Your team already runs realtime infrastructure and a 24/7 on-call rotation, with deep expertise in Go and Redis or NATS, so one more service is a marginal cost. | Running realtime infrastructure and an on-call rotation would be new work for your team, and you’d rather spend that time on your product. |
| Data residency or network isolation requirements mean everything has to run inside your own infrastructure. | A third-party platform meets your data requirements, and you want one that commits to its uptime with a 99.999% SLA on Business and Enterprise plans. |
| Message volume and connection counts are small and predictable, so operational overhead stays low. | Traffic is spiky or growing, and you want capacity to scale on demand. |
| Your users are concentrated in one region, close to where your cluster runs. | Your users are spread worldwide and need low latency and continuity through a regional outage. |
| Your application can tolerate an occasional lost or out-of-order message, or already handles recovery and deduplication itself. | Messages must arrive in order and exactly once, with automatic recovery after a disconnect. |
Centrifugo is a capable open-source server, and for teams that already run realtime infrastructure at small or predictable scale, it can be a sound choice. Running it in production, though, means your team owns the guarantees, the capacity planning, and the on-call that keep it reliable.
Choosing a managed platform that handles these natively means your team can spend that time building features instead.
Start building on Ably for free, or talk to the team about migrating from Centrifugo.
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Max Freiert
Product Group Lead
Ably copes easily with big loads. We don’t have to worry about stability, even when we get huge traffic spikes.”
Johan Bengtsson
CTO
Ably delivers all the performance and reliability we need as well as taking our compliance and encryption requirements in its stride.”
Jeremy Hutchings
CTO
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Senior Director, Technical Operations
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IT Infrastructure Team Lead
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Principal Product Engineer, Fin
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Brad Ward
Co-founder and CTO, TeamRetro
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