# gnea/grbl

An open source, embedded, high performance g-code-parser and CNC milling controller written in optimized C that will run on a straight Arduino

Repository: https://github.com/gnea/grbl
Canonical: https://ross.abutalabs.com/products/gnea-grbl
Homepage: https://github.com/gnea/grbl/wiki
Language: C
License: NOASSERTION
License Family: other
Last push: 2024-06-12T13:42:33+00:00

## Health v2 (maintenance only)
Score: 23/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 0, release rhythm 8, longevity 100
- inputs: {"age_days": 3634, "days_push": 812, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- 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 4529, forks 1700 (observed 2026-08-28T04:08:52.956024+00:00)

## What it is
Grbl is an open-source, high-performance g-code parser and CNC milling controller firmware written in optimized C for AVR-based Arduino boards like the Uno and Nano. It delivers jitter-free 30kHz step pulses, full acceleration planning with look-ahead, real-time overrides, jogging, and laser mode for hobby CNC machines, laser cutters, and similar motion-control projects.

## Use cases
- control a DIY CNC milling machine from an Arduino
- run a laser cutter with g-code firmware
- build a pen plotter or drawing machine
- flash pre-compiled firmware onto an Arduino Uno for motion control
- parse standards-compliant g-code from CAM tools on embedded hardware
- add smooth acceleration and look-ahead planning to a hobby CNC

## When to choose
- you need proven, low-cost motion-control firmware for an AVR Arduino (328p)
- you want a lightweight g-code controller with real-time overrides and laser mode
- your hardware is limited and you need highly optimized C firmware
- you are maintaining or repairing existing Grbl-based machines

## When to avoid
- you need active development, bug fixes, or new features - the project is discontinued since 2019
- you want support for newer 32-bit boards - consider grblHAL, FluidNC, or µCNC instead
- you need macro functions, variables, or canned cycles in g-code
- you require a GUI - Grbl is firmware only and needs external sender software

## Facets
- artifact type: library
- maturity: abandoned
- function: parser, embedded, interpreter
- domain: hardware, robotics, embedded-systems
- platform: embedded, iot, c
- tags: cnc, g-code, motion-control, arduino, firmware, laser-cutter, 3d-printing, discontinued, automation

## Member repositories
- gnea/grbl (main) score 23

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:08:52.956024+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 2026-08-29T18:20:13.652781+00:00, confidence not recorded.
  - readme: https://github.com/gnea/grbl (fetched 2026-08-28T04:08:52.956024+00:00, sha 92e4eb454e5e)
  - homepage: https://github.com/gnea/grbl/wiki (fetched 2026-08-29T09:05:57.369219+00:00, sha e9fce575b7e0)
- Data as of 2026-08-30T08:39:29.467469+00:00.