G-Code Modifier
A browser-based G-code editor and print analyzer for 3D printing. Inspect layers in 3D, simulate prints, detect potential failures before they happen, and modify G-code — all without installing anything.
Try it live — no download required.
Features
| |
|---|
| 3D Visualization — WebGL layer viewer with motion-type coloring, travel moves, and interactive camera | Print Analysis — Thermal simulation, structural analysis, and motion kinematics with 12 heatmap overlay modes |
| Warp Prediction — 3D warp mesh with material-aware failure prediction and adjustable deformation preview | Hole Detection — Scan all layers to find holes, calculate insert depths, and auto-add pauses |
| Print Simulation — Move-by-move playback with speed control and automatic pause detection | Edit Mode — Select, edit, or delete individual G-code moves directly in 3D with live preview |
| Layer Modifications — Pauses, filament changes, Z-offsets, eject sequences, recovery, and custom G-code | G-code Reference — 40+ commands with firmware-specific notes and click-to-insert |
Getting Started
- Open the live version or open
gcode-modifier.html locally (WebGL2 required)
- Select your firmware from the dropdown (Bambu Lab, Klipper, Marlin, RepRapFirmware)
- Drop a
.gcode / .gco / .g file onto the page
- Browse layers, run analysis, add modifications, and export
Slicer Compatibility
| Slicer | Status |
|---|
| Cura, Bambu Studio, PrusaSlicer, OrcaSlicer, SuperSlicer, Simplify3D, ideaMaker | Fully supported |
PrusaSlicer exports binary G-code by default. Uncheck the binary option in preferences to export plain .gcode.
For Developers
Source lives in src/ as ES modules. A zero-dependency build script inlines everything into a single gcode-modifier.html.
node build.js # build
node --test # run tests
Edit files in src/, not gcode-modifier.html directly. Run both commands before committing.
Documentation
- User Guide — detailed feature documentation, keyboard shortcuts, firmware profiles
- Analysis Theory — thermal model, structural analysis, motion kinematics
- DISCLAIMER.md — safety notice and liability
License
MIT — see DISCLAIMER.md for safety and liability terms.
