CNC GCode Tools
In development and not fully tested. Features may change or not work as expected, and a preview is an estimate. Check your toolpaths and stay with the machine when you run a job.

See the cut before the machine makes it

A G-code viewer for FluidNC and GRBL machines: the toolpaths in 3D, the stock carved as the job plays, parametric G-code expanded, and the running job followed on the machine. Free, and it runs entirely in your browser.

Try it with a demo job Open your own file Get it for your controller
The viewer on a desktop: G-code on the left, a 3D view of a part being carved from stock in the middle, toolpaths and stock settings on the right The viewer on a phone, with tabs along the bottom

One viewer, four places to use it

The same viewer, built for each place you prepare or run a job. All of them work on a phone, and none send your files anywhere.

Browser

Web viewer

Open G-code files from your computer. Recent files and a FluidNC config.yaml are remembered.

Open the viewer Try the demo job · or download gcodeviewer.html to use offline
FluidNC WebUI v3

WebUI extension

Preview files on the SD card, run them, and follow the job with progress, time left and feed hold.

  1. Copy gcodeviewer.html.gz to the SD card (not the controller's flash, which is small)
  2. In the WebUI, add an extension with the source /sd/gcodeviewer.html
Download extension About 68 KB, installed on the SD card
FigUI

FigUI plugin

Beside FigUI's DRO and jog controls: preview SD card files with the stock simulation and follow the job FigUI runs.

  1. Unzip figui-plugin.zip
  2. FigUI → Plugins → Add → the folder
Download plugin About 70 KB
VS Code

VS Code extension

Highlighting, completions, validation and expansion for FluidNC G-code, with the viewer beside the editor.

  1. Extensions → … → Install from VSIX
  2. Choose cnc-gcode-tools.vsix
Download .vsix Also for Cursor and VSCodium

What it shows you

Built around FluidNC, and fine with any GRBL-style G-code.

The machined part

The stock is carved with each tool's real shape as the job plays: flat, ball, bull nose, V-bit, chamfer and tapered ball.

Real-time playback

Each move takes its estimated time from feeds, rapid rates and acceleration. Scrub, step, or play at up to 500x.

Parametric G-code

FluidNC variables, expressions, conditionals and loops are expanded, and the plain G-code can be downloaded.

Messages, M0 and probing

(MSG, …) and (PRINT, …) messages appear as a pendant would show them, M0 stops wait for Resume, and Z probes touch the stock.

Problems flagged

Rapid moves that cut into the stock, and cuts deeper than a tool's flutes, are listed with their lines.

Jobs in several files

A job split by tool builds on the earlier files (PriorJob), so each one starts from the stock the last one left. Try the whole demo job in one file, or its V-bit file on the earlier bits' cuts.

Also here

Font Creator

Draw single-line fonts for engraving and laser cutting, with kerning, then turn text into G-code. Imports and exports SVG fonts.

Open Font Creator