skywind3000/kcp

Health v2 · maintenance only

Adoption not part of the score

16920 stars · 2633 forks observed · 2026-09-29

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-29, confidence not recorded

KCP is a fast and reliable ARQ (Automatic Repeat reQuest) protocol implemented as a pure algorithm in C, consisting of just two source files (ikcp.h and ikcp.c). It trades 10%-20% extra bandwidth for 30%-40% lower average latency compared to TCP, and requires the user to supply the underlying packet transport (e.g., UDP) via callbacks.

Use cases

• reduce latency for real-time game networking over UDP
• add reliable delivery on top of a custom UDP protocol
• build a low-latency tunnel or proxy transport
• implement P2P communication with reliable ordering
• speed up data transfer on lossy high-latency networks
• embed a reliable ARQ layer into an existing protocol stack

When to choose

• you need TCP-like reliability with much lower latency than TCP
• you want a tiny, dependency-free C library you can drop into any project
• you already have a UDP transport layer and just need reliability on top
• you are building games, RTC, or tunnels where per-packet latency matters more than bandwidth

When to avoid

• you need maximum bandwidth throughput rather than minimal latency
• you want a complete out-of-the-box transport with sockets handled for you
• you cannot tolerate any bandwidth overhead (10%-20%)
• you need a high-level networking API rather than a low-level protocol algorithm

Facets

library · maturity stable

networking concurrency networking microservices gaming-tools cpp c cross-platform udp arq low-latency reliable-transport protocol-implementation game-networking tunnel real-time

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