Free Online G-Code Viewer & Analyzer

What You Can Do With CutViewer's G-Code Viewer

CutViewer renders your G-code as an interactive 3D toolpath that you can rotate, zoom, and inspect from any angle. It's not a flat 2D plot — you see the full three-dimensional path your tool will take, with rapids and cutting moves clearly distinguished. This makes it easy to spot problems like unexpected retracts, missed areas, or collisions before your material is on the machine.

The viewer handles large files without choking. Programs with millions of lines parse in the background using a web worker, so the UI stays responsive while your file loads. We've tested files up to 50MB without issues — no arbitrary upload limits, no "file too large" errors.

CutViewer includes a built-in G-code editor with syntax highlighting. You can read through your program line by line, jump to any point in the toolpath, and see exactly where the tool is at each step. Edit your G-code directly and the toolpath updates to reflect your changes — useful for tweaking feed rates, fixing coordinates, or stripping out unwanted sections without round-tripping back to your CAM software.

Animation lets you play through the cutting sequence in order, so you can verify not just where the tool goes, but in what order. Step through line by line or let it run — the progress slider lets you scrub to any point in the program.

Supported G-Code Formats

CutViewer reads standard G-code and works with files from virtually any CAM software or CNC controller.

Extension	Common Sources
.gcode	Fusion 360, Mastercam, VCarve, Carbide Create
.nc	Fusion 360, Mastercam, BobCAD, SolidCAM
.tap	Mach3, Mach4, many post processors
.ngc	LinuxCNC, GRBL
.cnc	Various CAM software

Any file containing standard G-code will work regardless of extension. CutViewer supports G00/G01 rapid and linear moves, G02/G03 arcs, plane selection (G17/G18/G19), inch and metric units (G20/G21), absolute and incremental positioning (G90/G91), and work coordinate systems (G54–G59). See the full list in the G-code reference.

How CutViewer Compares

Feature	CutViewer	NC Viewer	gcode.ws
3D visualization	Yes	Yes	2D only
Large file support	50MB+	~15MB limit	~23MB limit
In-browser G-code editor	Yes	Yes	No
Toolpath animation	Yes	Limited	No
Dark mode	Yes	No	No
No signup required	Yes	Yes	Yes
Mobile support	Yes	Limited	Yes
CNC G-code support	Yes	Yes	No (3D printing only)

Works With Your CAM Software

CutViewer reads standard G-code, so it works with the output of any CAM package. If your software generates G-code, CutViewer can visualize it.

Fusion 360 — The most popular hobbyist and professional CAM tool. CutViewer handles all standard Fusion 360 post processor output, including adaptive clearing and multi-axis toolpaths.

Carbide Create — The free CAM software from Carbide 3D, popular with Shapeoko and Nomad users. Export your G-code and drag it into CutViewer to verify before cutting.

VCarve / Aspire — Vectric's carving and routing software generates clean G-code that CutViewer renders without issues. Useful for verifying complex V-carve toolpaths.

Mastercam — Industry-standard CAM. CutViewer handles the full range of Mastercam post processor output.

MeshCAM — Drop your MeshCAM G-code into CutViewer to check toolpaths before running. Works with all MeshCAM output formats.

HSMWorks / SolidCAM / BobCAD — Any CAM package that outputs standard G-code is supported. No special configuration needed.

GRBL / Mach3 / Mach4 / LinuxCNC — CutViewer works with G-code written for any of the common CNC controllers. If your machine can run it, CutViewer can display it.

Frequently Asked Questions