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ably

Realtime client library for Ably, the realtime messaging service

WEEKLY DOWNLOADS 453.4K
STARS 360
FORKS 58
OPEN ISSUES 225
GZIP SIZE 51.1 kB
UNPACKED SIZE 8.9 MB
LAST UPDATED 3mo ago
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ably downloads — last 12 months

Download trends for ably1 download series from Jun 2025 to May 2026. Use left and right arrow keys to inspect monthly values.01.1M2.2M3.3M4.4MJun 2025SepDecMarMay 2026
ably
ABOUT ABLY

The Ably Realtime client library for JavaScript provides robust connectivity to the Ably Platform, a managed global realtime messaging service. It solves the complexity of building and scaling realtime features, such as live chat, collaborative editing, and live data feeds, by abstracting away the underlying WebSocket infrastructure and managing connections, reconnections, and message delivery.

This library is designed for developers building realtime applications who require a reliable, scalable, and feature-rich backend without managing their own servers. Its core philosophy centers on developer experience and operational simplicity, enabling rapid development of interactive user experiences. The client library caters to a wide audience from frontend developers using frameworks like React or Vue to backend Node.js developers.

The API exposes several key patterns for realtime communication. Developers can use the `Realtime` class to establish a persistent connection and subscribe to channels using `channel.subscribe()`. Message publishing is handled via `channel.publish()`, while presence features allow tracking connected users. The library also offers stateless REST functionality for certain operations, complementing its realtime capabilities.

Integration is straightforward within modern JavaScript workflows. It plays well with frontend frameworks and build tools, supporting TypeScript out-of-the-box for enhanced type safety. Its Node.js compatibility means it can be used server-side for bridging or backend logic, fitting seamlessly into full-stack applications. The library is actively maintained and has a substantial number of open issues, indicating ongoing development and community engagement.

With a gzip bundle size of 51.1 kB, the library aims for a reasonable footprint in client-side applications. It is designed to handle high volumes of messages and concurrent connections efficiently, powered by Ably's global network. The package has been updated recently, suggesting ongoing support and feature enhancements for its users.

Developers should be aware that while the library handles many edge cases, a complete understanding of publish-subscribe patterns and realtime state management is still necessary for complex applications. The reliance on the Ably platform means network latency and Ably's specific service limitations should be considered for mission-critical, ultra-low-latency requirements.

WHEN TO USE
  • When implementing live chat features where messages need to be delivered instantly to multiple clients using `channel.publish()` and `channel.subscribe()`.
  • For building collaborative document editing applications that require real-time synchronization of changes via channel events.
  • When developing live data dashboards that update automatically in the browser as data changes on the backend, leveraging Ably's push notifications.
  • For creating multiplayer games where game state needs to be shared between players in real-time using bidirectional message streams.
  • When requiring presence information to show which users are currently connected to a specific service or channel using `channel.presence.get()`.
  • To integrate realtime elements like status updates or notifications into existing web applications without managing a dedicated realtime server.
WHEN NOT TO USE
  • If your application solely requires basic client-server request-response communication — a conventional REST API or GraphQL endpoint would be more appropriate.
  • For simple, infrequent state synchronization where polling or WebSocket libraries with less overhead would suffice.
  • If you need to implement a complex custom messaging protocol that deviates significantly from publish-subscribe patterns.
  • When your backend logic for managing realtime connections and message routing is already robust and built with custom WebSocket servers.
  • For applications where offline-first capabilities are paramount and sophisticated local data synchronization with conflict resolution is the primary requirement, as this library focuses on online realtime states.

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