# SanderMertens/flecs

A fast entity component system (ECS) for C & C++

Repository: https://github.com/SanderMertens/flecs
Canonical: https://ross.abutalabs.com/products/flecs
Homepage: https://www.flecs.dev
Language: C
License: NOASSERTION
License Family: other
Topics: ecs, c99, cpp11, cpp14, cpp17, data-oriented, data-oriented-design, entity-component-system, entity-framework, flecs, game-development, game-engine, game-engine-framework, gamedev, modern-cpp, no-dependencies, portable, production-ready
Last push: 2026-08-26T00:08:34+00:00

## Health v2 (maintenance only)
Score: 92/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 78, longevity 100
- inputs: {"age_days": 2929, "days_push": 8, "days_rel": 66, "gap_med": 62.5, "n_releases_24m": 11}
- flags: no_license
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 8619, forks 615 (observed 2026-08-28T04:10:23.848804+00:00)

## What it is
Flecs is a fast, lightweight Entity Component System (ECS) framework for C99 and C++17 that enables building games and simulations with millions of entities. It features an archetype/SoA storage, entity relationships, prefabs, hierarchies, a query language, and a lockless multithreaded scheduler.

## Use cases
- build a game engine with an entity component system architecture
- simulate millions of entities efficiently
- manage entity relationships and hierarchies in a game
- run game logic in parallel across CPU cores
- serialize game state to JSON with reflection
- write data-oriented gameplay systems with queries

## When to choose
- you need a production-ready, zero-dependency ECS for C or C++
- you want high-performance archetype-based storage for large entity counts
- you need entity relationships, prefabs, or hierarchies in an ECS
- you want to run systems in parallel on multiple cores
- you target multiple platforms including the browser via emscripten

## When to avoid
- you need a full game engine with rendering, audio, and physics built in
- your project is small enough that an ECS adds unnecessary complexity
- you require a garbage-collected language binding as your primary workflow
- you need an ECS with a large plugin ecosystem beyond the core framework

## Facets
- artifact type: framework
- maturity: stable
- function: game-engine, simulation, serialization, concurrency
- domain: simulation
- platform: cross-platform, cpp, c, wasm
- tags: ecs, entity-component-system, data-oriented-design, c99, cpp17, no-dependencies, archetype-storage, entity-relationships, prefabs, multithreading, game-development, gamedev

## Member repositories
- SanderMertens/flecs (main) score 92

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:10:23.848804+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 2026-08-29T17:25:52.935633+00:00, confidence not recorded.
  - readme: https://github.com/SanderMertens/flecs (fetched 2026-08-28T04:10:23.848804+00:00, sha b1badc794c3f)
  - homepage: https://www.flecs.dev (fetched 2026-08-29T08:26:11.780246+00:00, sha 83e88a898dc8)
- Data as of 2026-08-30T08:39:29.467469+00:00.