# antirez/rax

A radix tree implementation in ANSI C

Repository: https://github.com/antirez/rax
Canonical: https://ross.abutalabs.com/products/antirez-rax
Language: C
License: BSD-2-Clause
License Family: permissive
Last push: 2023-11-26T12:39:33+00:00

## Health v2 (maintenance only)
Score: 32/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 0, release rhythm 35, longevity 100
- inputs: {"age_days": 3472, "days_push": 1011, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1267, forks 177 (observed 2026-08-28T04:04:11.372270+00:00)

## What it is
Rax is a fully featured radix tree (trie) implementation written in portable ANSI C99, originally created for Redis. It emphasizes a balance of performance and memory usage with packed nodes, cache-friendly edge scanning, iterators, and OOM-safe APIs.

## Use cases
- implement a radix tree in C
- memory-efficient key lookup data structure
- prefix search in C
- embed a trie in a database engine
- sorted iteration over string keys
- battle-tested radix tree library

## When to choose
- you need a fast, memory-conscious radix tree in C
- you want iterators that tolerate concurrent tree modification
- you need a portable ANSI C implementation with fuzz-tested robustness

## When to avoid
- you need a general-purpose hash table rather than prefix-based keys
- you want a high-level language binding out of the box
- you need actively developed new features

## Facets
- artifact type: library
- maturity: maintenance
- function: parser, search-engine, fuzzing
- domain: databases, developer-tools
- platform: c, cross-platform
- tags: radix-tree, data-structures, ansi-c, redis, trie, memory-efficient, algorithms, linux

## Member repositories
- antirez/rax (main) score 32

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:04:11.372270+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 2026-08-30T05:03:41.733586+00:00, confidence not recorded.
  - readme: https://github.com/antirez/rax (fetched 2026-08-28T04:04:11.372270+00:00, sha 2a55d59f4158)
- Data as of 2026-08-30T08:39:29.467469+00:00.