What you can check before you print
- The first layer. Select layer 1 and look at its shape and position. Compare the toolpath bounds with your build volume.
- Travel moves. Moves without extrusion are drawn as travel. Long travel paths across open areas are where stringing tends to come from, and you can see how much of them there is.
- Retractions. Filament pull-backs are marked with a small marker, so you can see where they happen.
- Layer by layer. Step through layers or the movement sequence to watch the part build up. Full-colour moves are earlier, dimmed moves are later.
- Temperatures and settings. Heater commands such as M104, M109, M140 and M190 do not draw anything, but you can find them with the source search and click through to the surrounding moves.
How the viewer reads a 3D printing file
| What you see | How it is decided |
|---|---|
| Extrusion | A move with a positive extrusion (E) change. |
| Travel | A move without extrusion. |
| Retraction | An extrusion-only move with a negative change. |
| Layers | From slicer comments (;LAYER:, ;LAYER_CHANGE, ; layer n) when present; otherwise from the Z height of extruding moves, so travel Z-hops do not create layers. |
| Extrusion mode | Absolute (M82) and relative (M83) are both handled. |
If the file has moves before the first layer marker, they are listed as a separate start-up entry instead of being mixed into layer 1. Files printed in spiral or vase mode, or with Z changing on almost every move, may show no layers; the viewer says so instead of inventing them.
Slicers
Any slicer that exports plain-text G-code works, including Cura, PrusaSlicer, Orca Slicer, Bambu Studio and Simplify3D. Export a standard .gcode file. Binary .bgcode files and Bambu .gcode.3mf packages are not supported; see the troubleshooting guide.
What it does not do
It does not estimate print time or filament use, edit G-code, or connect to a printer. It is for looking at a file, not a guarantee that a print will succeed.
3D printer G-code viewer questions
Is it free? Yes, with no account.
Can I see the print in 3D and 2D? Yes. The 3D view is a free camera; the 2D view looks straight down the Z axis.
Why does my file show no layers? Usually vase mode, or a file with no layer comments and no stable Z levels. See troubleshooting.
Not sure how to open a file? See how to open G-code files, or go back to the online G-code viewer.