A last look before the print starts

What it is

A G-code file is the finished instruction list a printer follows: every move, every temperature change, every millimetre of filament. It is plain text, and it is the last artifact between a design and several hours of machine time — but it is close to unreadable without a picture.

GCODE/VIEW turns that text back into something you can look at. Drop in a .gcode, .gco, or .g file and you get the whole toolpath in 3D, any single layer flat in 2D, the original commands with search and line jumps, and a summary of print time, filament use, layer count, and print size.

Why it exists

Slicers already preview what they slice. The gap is everything that happens after that: a file someone sent you, a file from a print farm or a marketplace, a file you sliced last month on a machine you are not sitting at now. Opening a full slicer — assuming you have the right one and the original project — is a heavy way to answer a light question.

The other half of the reason is where those files go. A design file describes a real object, sometimes one that is not public yet. Uploading it to an unfamiliar server to look at it for thirty seconds is a poor trade, so this viewer does not ask for the upload. Your file is opened with the browser's local file API, parsed in a background worker, and drawn on your own graphics hardware. It never leaves the tab.

How it works

• Reading — the browser's File API hands the page the text of the file you chose. There is no transfer step.
• Analysis — a Web Worker parses the commands off the main thread, so the interface stays responsive on files with millions of lines.
• Rendering — the toolpath is drawn with WebGL on your own device.
• Nothing stored — the file lives in the page's memory. Close or reload the tab and it is gone; there is no history, no account, and no saved copy.

Full detail on what is and is not collected is in the privacy policy.

What it is not

• Not a slicer. It reads sliced output; it does not produce it, and it does not edit your file.
• Not a CNC tool. The analysis is built for 3D-printer G-code from slicers such as Cura, PrusaSlicer, Bambu Studio, OrcaSlicer, and SuperSlicer. Milling and engraving programs are outside its scope.
• Not a guarantee. Time and filament figures are estimates — the slicer's own, or ones calculated from the motion in the file. Real prints are affected by acceleration, heating, and firmware behavior.

Treat it as an independent second look, not a replacement for reviewing critical jobs in your slicer and following your printer manufacturer's guidance.

Beyond the viewer

Two reference sections sit alongside the tool for the moments when a line of G-code needs explaining rather than drawing: a command reference covering syntax, firmware differences, and common mistakes, and a glossary of the terms that appear in slicer output. New to the viewer itself? Start with how to use it.