# crossoverJie/cim

📲cim(cross IM) 适用于开发者的分布式即时通讯系统

Repository: https://github.com/crossoverJie/cim
Canonical: https://ross.abutalabs.com/products/cim
Homepage: https://crossoverjie.top/categories/Netty/
Language: Java
License: MIT
License Family: permissive
Topics: netty, tcp, heartbeat, im
Last push: 2026-04-05T02:05:13+00:00

## Health v2 (maintenance only)
Score: 57/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 75, release rhythm 8, longevity 100
- inputs: {"age_days": 3027, "days_push": 151, "days_rel": 450, "gap_med": 245, "n_releases_24m": 2}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 9492, forks 2866 (observed 2026-08-28T04:10:31.457611+00:00)

## What it is
CIM (Cross IM) is a distributed instant messaging system for developers built with Java, Netty, and Spring Boot. It provides server and client components plus an SDK for building scalable IM platforms, app message push, and IoT massive-connection messaging.

## Use cases
- build a distributed instant messaging system
- push messages to mobile apps at scale
- handle massive IoT device connections with long-lived TCP
- learn Netty long-connection heartbeat and reconnection design
- run group chat and private chat for developers
- embed a chat client SDK into my own application

## When to choose
- you want a self-hosted, developer-oriented IM foundation in Java
- you need horizontal scaling with Netty-based TCP long connections
- you want a learning reference for high-concurrency messaging architecture

## When to avoid
- you need a production-ready turnkey chat product with web/mobile clients out of the box
- you need offline messages and message encryption, which are not yet implemented
- your stack is not JVM-based and you cannot run Java servers

## Facets
- artifact type: framework
- maturity: active
- function: websocket, message-queue, rpc, middleware, http-server
- domain: messaging-platforms, developer-tools, iot
- platform: jvm, cross-platform
- tags: instant-messaging, netty, tcp, heartbeat, chat, distributed-systems, protobuf, im-sdk, messaging, real-time, docker

## Member repositories
- crossoverJie/cim (main) score 57

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:10:31.457611+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-29T17:22:02.656050+00:00, confidence not recorded.
  - readme: https://github.com/crossoverJie/cim (fetched 2026-08-28T04:10:31.457611+00:00, sha 335661abe8ca)
  - homepage: https://crossoverjie.top/categories/Netty/ (fetched 2026-08-29T08:21:52.889770+00:00, sha 4a0d62ab9b88)
  - site_page: https://crossoverjie.top/about (fetched 2026-08-29T08:21:52.898789+00:00, sha 4516b2c2951a)
- Data as of 2026-08-30T08:39:29.467469+00:00.