Why our customers choose Ably over PubNub
Ably is an enterprise-grade serverless WebSockets platform for pub/sub messaging at the edge. Our customers trust in Ably to power scalable and realtime online user experiences that will work anywhere in the world, without fail.
We provide an elastic, hyper-reliable global infrastructure that also comes with the flexible building blocks needed for creating rich user experiences. Everything is offered via consistent and intuitive APIs.
Focus on building realtime apps that delight customers. We'll handle the rest.
Ably is a serverless edge messaging platform designed to stream realtime messages at extreme scale to web, mobile, and IoT devices, over a fault-tolerant, autoscaling global edge network. We deliver 750+ billion messages to more than 300 million end-users each month.
As a managed solution, Ably enables you to:
Easily build high-performance realtime functionality that delights your users.
Reduce engineering and DevOps efforts - there's no complex realtime infrastructure for you to provision and maintain.
Key Ably advantages vs PubNub
Global median round trip latencies of sub 65ms
Ably's round trip latencies, measured as the time taken to publish a message on one connection and receive a message on another connection, dependably range from 5ms to 200ms, with a median global latency of 65ms.
PubNub advertises sub-250ms worldwide latencies.
QoS & message delivery guarantee
Ably provides guaranteed message delivery and continuity across disconnections. Publishers only receive an ACK when data is persisted in two locations, and subscribers never lose data during brief disconnections as we maintain connection state for each client on our servers.
From PubNub: "PubNub is not a guaranteed message delivery service."
Continuity and connection state recovery
Ably provides continuity for clients that become disconnected for reasons such as going through a tunnel or changing networks. We store the connection state for each client on our servers so that clients that reconnect within two minutes can resume their connection and receive all messages published whilst they were disconnected.
PubNub does not store connection state but does queue up to 100 messages upon disconnection, and can 'catch' clients back up on those messages upon reconnection. From PubNub: "The default message queue size is 100 messages. Consequently, publishing past 100 messages inevitably results in older messages overflowing the queue and getting discarded."
Reliable message ordering
Ably ensures that messages are delivered to persistently connected subscribers in the order they were published on each channel using the First-in-First-Out (FIFO) pattern.
Idempotent message publishing
Ably supports idempotent publishing across all our native client library SDKs.
Delta Message Compression
Ably supports message delta compression on a per channel basis.
Server-Sent Events (HTTP Streaming) protocol support
JSON Web Token support
Ably allows for not only Ably Tokens to be embedded within JWTs, but also for JWTs to be signed by Ably API keys and used themselves for authentication.
Configurable private key permissions
Ably provides support for private API keys with configurable permissions including restrictions on channels or operations.
PubNub does not provide configurable private key permissions