# erincatto/box2d

Box2D is a 2D physics engine for games

Repository: https://github.com/erincatto/box2d
Canonical: https://ross.abutalabs.com/products/box2d
Homepage: https://box2d.org
Language: C
License: MIT
License Family: permissive
Last push: 2026-08-26T06:40:01+00:00

## Health v2 (maintenance only)
Score: 74/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 28, longevity 100
- inputs: {"age_days": 4190, "days_push": 7, "days_rel": 456, "gap_med": 44, "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 10303, forks 1804 (observed 2026-08-28T04:10:41.560253+00:00)

## What it is
Box2D is a widely used open-source 2D rigid body physics engine for games, written in portable C17 with a data-oriented design, multithreading, and SIMD support. It provides collision detection, joints, motors, springs, ray casts, and spatial queries for making game objects move realistically.

## Use cases
- simulate 2d rigid body physics in a game
- add realistic collision detection to a 2d game
- implement joints motors and springs between game objects
- perform ray casts and overlap queries in a 2d world
- build a physics sandbox or physics puzzle game
- add procedural animation driven by physics to a game engine

## When to choose
- you need a battle-tested 2D physics engine with continuous collision detection
- you want a portable C library with multithreading and SIMD performance
- you are building a 2D game with many dynamic bodies and need island-based sleeping
- you need collision queries and a dynamic tree for spatial sorting

## When to avoid
- you need 3D physics simulation (use Box3D or another 3D engine)
- you want a high-level engine-integrated physics solution with visual editors
- you are not comfortable compiling and linking C code yourself

## Facets
- artifact type: library
- maturity: stable
- function: simulation, graphics, game-engine, math
- domain: simulation, graphics, cross-platform
- platform: cpp, c, cross-platform, windows, game-engine
- tags: physics-engine, rigid-body-simulation, collision-detection, 2d-games, c17, multithreading, simd, game-development, linux, macos

## Member repositories
- erincatto/box2d (main) score 74

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:10:41.560253+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 2026-08-29T17:19:11.438351+00:00, confidence not recorded.
  - readme: https://github.com/erincatto/box2d (fetched 2026-08-28T04:10:41.560253+00:00, sha b0438b472ff3)
  - homepage: https://box2d.org (fetched 2026-08-29T08:18:35.470193+00:00, sha c11e332f0106)
  - site_page: https://box2d.org/about (fetched 2026-08-29T08:18:35.479288+00:00, sha 490da859b17e)
  - site_page: https://box2d.org/documentation (fetched 2026-08-29T08:18:35.481135+00:00, sha 89e27a64c1ea)
  - site_page: https://box2d.org/documentation3d (fetched 2026-08-29T08:18:35.483476+00:00, sha ed4bf1d107a8)
  - site_page: https://box2d.org/doc_version_2_4 (fetched 2026-08-29T08:18:35.485531+00:00, sha 161a23c6ded6)
- Data as of 2026-08-30T08:39:29.467469+00:00.