How to open a G-code file
G-code is plain-text machine instruction, but opening it in a text editor does not show the shape of the toolpath. A viewer turns supported motion commands into a spatial preview while keeping the source available.
Drag a .gcode, .gco, or .g file into the viewer, or use Open G-code. The file is read locally in the browser, then becomes available as a 3D preview, a single-layer 2D view, and the original line-by-line source.
0101 / Inspection steps
Inspection steps
Use the views in this order so the broad shape, the layer detail, and the source line tell one consistent story.
- 01
Choose a sliced 3D-printer file
Use the G-code exported by your slicer, not the original STL, 3MF, or CAD model. This viewer deliberately does not accept generic CNC .nc programs.
- Supported filename endings are .gcode, .gco, and .g.
- Keep the source slicer project if you may need to change settings and export again.
- 02
Open it in the browser
Drop the file on the workbench or select it with the file picker. Reading and analysis happen on the current device; the G-code is not sent to the site server.
- Wait for the ready state before judging the preview.
- Read any partial or resource-limit notice instead of assuming every view is complete.
- 03
Pick the view that answers your question
Use 3D for the complete path, 2D for one layer from above, and Source for exact commands and comments. The file summary remains the fastest place to check time, filament, layers, and dimensions.
- Turn on travel moves only when you need to study non-extruding motion.
- Click a 2D segment to connect geometry back to its source line.
02 / What to look for
What to look for
These are observable clues in the file, not guarantees about the physical print.
Ready state
The workbench reports that the file is open and available for inspection.
Three consistent views
3D, 2D, and source should describe the same loaded file at different levels of detail.
Explicit provenance
Summary values say whether they came from slicer metadata, measured commands, an estimate, an assumption, or are unavailable.
03 / What this cannot prove
What this cannot prove
A G-code viewer reads planned commands. It does not see nozzle condition, wet filament, calibration, or how firmware and hardware execute the job.
- This is a viewer for sliced 3D-printer G-code, not a slicer, editor, CNC simulator, or a live connection to a printer.
- Very large or unusually dense files may keep summary analysis while skipping a resource-heavy preview; the interface reports that state explicitly.
04 / Common questions
Common questions
Can I open G-code without installing software?+
Yes. The browser viewer needs no installation. A desktop slicer viewer remains useful when you need its printer profiles or editing workflow.
Does opening the file upload it?+
No. The browser reads and analyzes the selected file locally. Normal site analytics do not receive the G-code contents.
06 / Technical sources
Technical sources
The workflow is grounded in current viewer behavior and these official technical references.