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It's a split decision.
Choose Ably if you want a hosted realtime API with named SDKs across JavaScript, Python, Java, .NET, Go and other languages, plus a lower listed Pro entry price. Choose PubNub if message persistence, presence, per-user and per-channel permissions, encryption or audit logs matter to your application. Both provide managed realtime infrastructure. Their free tiers measure usage differently, so compare your expected MAUs, transactions and storage needs before choosing.
01Side by side
| Ably | PubNub | |
|---|---|---|
| Production entry price | Pro: $29/month, billed annually | Starter: $98/month |
| Free tier | Up to 500 MAUs; all products | Up to 200 MAUs or 1M transactions |
| API and SDKs | Consistent SDKs across 12 named languages | Pub/sub API; Web, iOS and Android |
| Integrations | Webhooks, cloud functions, Kafka, Terraform | Kafka, SQS, Kinesis, S3, webhooks |
| Platforms | JavaScript, React, Python, Java, Go, more | Web, iOS, Android |
| Deployment model | Hosted realtime infrastructure | Managed realtime infrastructure |
| Scaling and reliability | Delivery, ordering, failover; 99.999% SLO on Pro | Multi-region failover; up to 99.999% Pro SLA |
| Realtime features | Pub/sub, chat, state sync, collaboration, AI transport | Pub/sub, persistence, presence, permissions, encryption |
Ably Choose Ably if
- Choose Ably if you need SDKs for a broad range of languages.
- Choose Ably if the $29/month annual Pro entry fits your budget.
- Choose Ably if you want chat, collaboration and AI transport APIs.
PubNub Choose PubNub if
- Choose PubNub if reconnecting clients need message persistence.
- Choose PubNub if you need presence and per-channel permissions.
- Choose PubNub if its listed Kafka, SQS or Kinesis integrations fit your stack.
02Pricing at real usage
Ably's Free plan allows up to 500 MAUs, includes access to all products and features, and has no commitment. Pro starts at $29 per month, billed annually, and includes 1K MAUs. Business is $349 per month, also billed annually, with 1K MAUs. Enterprise pricing is custom and annual-only. PubNub Free allows up to 200 MAUs or 1M transactions, with 1GB of storage for seven days. Starter costs $98 monthly and includes 1,000 MAUs and up to six months of storage. Pro uses custom MAU packages: the pricing page gives examples of $550 monthly for 10,000 MAUs and $2,100 for 50,000, while noting 50,000+ is custom. Ably's published tiers don't specify overage rates. Ask both vendors how your message, MAU and storage patterns affect the bill.
03API, SDKs and integration
Ably describes a pub/sub API with message guarantees and separate APIs for chat, AI transport, state sync, collaboration and database-to-frontend sync. Its homepage lists SDKs for JavaScript, React, Python, Java, .NET, Ruby, Flutter, Objective-C, Swift, PHP, Go and C#.NET, and says they provide a consistent, idiomatic API. Listed integrations include webhooks, AWS Lambda, Azure Functions, Cloudflare Workers, Kafka, Kinesis, SQS, Apache Pulsar and Terraform. The homepage links to documentation but doesn't identify a CLI. PubNub's core model is publish/subscribe messaging over named channels. Its listed capabilities include persistence, data sync and presence; its developer navigation links to documentation, tutorials, demos and SDKs, and names Web, iOS and Android platforms. Integrations include push notifications, event forwarding to Kafka, SQS, Kinesis, S3 and webhooks, plus a Kafka connector. Neither homepage identifies a CLI; check the vendor's current docs if CLI support is required.
04Open source, self-hosting and lock-in
Neither vendor's product pages state an open-source licence, self-hosting path or data-export guarantee. Treat both as managed services and confirm those requirements with the vendor before committing. Ably sells hosted realtime infrastructure; PubNub describes managed infrastructure, and its review characterizes the service dependency as meaningful. In either case, moving an application means more than changing an endpoint if its clients rely on vendor-specific channel behavior, persistence, presence, state-sync APIs or SDKs. Keep your application’s messaging interface behind an adapter where practical, and retain a canonical copy of data your app must preserve. Before launch, ask how to export stored messages and user or channel configuration, what formats are available, and whether migration support is included. Do not assume a protocol-compatible replacement or portable data from the presence of a pub/sub API.
Questions people ask
Is Ably cheaper than PubNub?
Ably lists Pro at $29 per month when billed annually, with 1K MAUs included. PubNub's Starter plan is $98 monthly and also includes 1,000 MAUs. That makes Ably's listed entry price lower, but compare annual billing, your transaction and storage needs, and any overage terms before estimating production cost.
Can I self-host Ably or PubNub?
Neither vendor's product pages state a self-hosting option. Both are presented as managed realtime services, so plan for a hosted-service dependency unless the vendor confirms otherwise. If self-hosting is a requirement, ask about deployment options, data export and migration before choosing.
Which platform has broader SDK coverage?
Ably names SDKs for JavaScript, React, Python, Java, .NET, Ruby, Flutter, Objective-C, Swift, PHP, Go and C#.NET. PubNub lists Web, iOS and Android platforms but does not name languages in its homepage text. Check the current SDK documentation for your specific framework and version.
Which is better for production reliability?
Both publish production reliability claims: Ably lists a 99.999% uptime SLO for Pro, while PubNub says its Pro plan offers up to a 99.999% uptime SLA. Ably's Business plan lists a 99.999% SLA. Compare the exact contract, exclusions, support response times and routing needs for your workload.