nchan.io

What It Is

Nchan is a Pub/Sub server built as an Nginx module, designed to provide scalable and flexible real-time message delivery for the modern web. It can run either as a standalone service or as an intermediary layer between an application and a large number of online subscribers. Messages are published to channels, and subscribers receive them through different protocols.

Core Capabilities

Its feature set is fairly comprehensive: publishers can use HTTP POST and WebSocket, while subscribers can use WebSocket, EventSource/SSE, Long-Polling, Interval-Polling, multipart/mixed, raw stream, HTTP chunked, and more. Messages can be buffered in memory, on disk, or in Redis, with per-channel buffer configuration and delivery guarantees for no duplicates and no message loss. A single subscription connection can subscribe to multiple channels, and channel IDs can come from query parameters, headers, URL regex matches, or other Nginx variables. Channel groups can also be used for usage statistics and limits, such as the number of channels, subscribers, messages, and memory or disk usage.

Deployment, Integration, and Documentation

Nchan clearly supports self-hosting and can be installed via system packages, Homebrew, source builds, Nginx dynamic modules, Heroku buildpacks, and other methods. It is deeply integrated with the Nginx configuration system, and Redis can be used to scale horizontally across multiple Nginx instances. Redis Cluster can further improve high availability. For integration, it provides an authorization mechanism similar to Nginx auth_request, and also supports HTTP hooks for subscription, unsubscription, publish upstream requests, and more. The documentation is very detailed, with many configuration snippets and protocol explanations, though developers unfamiliar with Nginx may face a learning curve.

Pricing and Value

The crawled text does not mention commercial pricing, paid editions, or SLA information. Since GitHub source code and source-based builds are available, its core offering appears suitable for free self-hosting. If a team already has Nginx/Redis operations experience, the value is excellent; if they prefer managed infrastructure, a dashboard, and commercial support, they may need to consider hosted alternatives.

Pros, Cons, and Best Fit

Its strengths are high concurrency, broad protocol compatibility, flexible configuration, horizontal scalability, and the ability to fit closely into an existing Nginx architecture. Its downsides are configuration complexity, with many capabilities requiring an understanding of Nginx locations, variables, Redis, HTTP semantics, and real-time protocol details. It is well suited to engineering teams that need to build their own real-time push, chat, notification, event streaming, or presence systems. It is less suitable for small teams that simply want a quick, low-code real-time messaging service.

Access from China

The crawled text does not provide information about network accessibility from mainland China, mirrors, payments, or commercial services, so its China access status is unknown. If access to GitHub or external package repositories is unstable, consider using domestic mirror sources, caching the source code yourself, or evaluating alternatives such as Socket.IO, Centrifugo, Mercure, and Pushpin.