How to use the viewer

Open a file

The viewer loads a small demo file on arrival, so every control works before you open anything of your own. The label above the preview reads LIVE DEMO until you load a file, then LOCAL FILE.

1. Drag and drop

   Drag a .gcode, .gco, or .g file onto the viewer panel. The panel highlights and shows “Drop G-code to inspect” while the file is over it.

2. Or use the button

   Select Open G-code at the top right of the viewer to pick a file with the normal file dialog.

3. Wait for the read

   The file is read and analyzed on your device. Large files take a few seconds; the status line says “Reading this file” while that happens, then “File ready to explore”.

Nothing is uploaded at any point. Reading, analysis, and rendering all happen in the browser tab.

Three views of the same file

Three tabs sit above the workspace, and all of them describe the file you just opened:

• 3D preview — the whole toolpath, layer by layer.
• 2D layer — a single layer seen from above.
• G-code — the original lines of the file, unchanged.

The file summary on the right stays visible in every view.

The 3D preview

Moving the camera

• Drag with the mouse to rotate the model.
• Hold Alt or Option and scroll to zoom. Plain scrolling keeps scrolling the page, so the viewer never traps the wheel.
• The +, −, and Reset buttons in the corner do the same job without a modifier key.

Stepping through layers

The slider below the preview selects the top layer to draw, and the readout beside it shows the layer number and its Z height. Build to layer stacks everything up to that layer; Single layer draws only that one. When the viewer is on screen, the left and right arrow keys step one layer at a time.

Display options

• Travel moves — show the moves that reposition the nozzle without printing plastic.
• Build grid — show or hide the bed grid and the box around the print.
• Color by — Layer is a height gradient, Feature paints outer walls, inner walls, infill, supports, bridges, and skirt or brim separately, and Speed bands the paths by the speed requested in the file. Feature and speed colors depend on what the slicer wrote into the file, and a legend appears under the display controls listing only the ones present.

The 2D layer view

This view draws one layer flat, seen from above, which is the easiest way to spot a gap, a thin wall, or an unexpected detour. Use Previous layer, Next layer, or the slider to move through the print.

• Colored solid lines are plastic printed on this layer. Show moves without printing adds the travel moves.
• Click any path to select it. The selection is outlined in white, and the panel below reports the G-code line it came from and the coordinates it ends at.
• See original instruction jumps to that exact line in the G-code view.

The heading also reports that layer's Z height in millimetres and the width and depth of what is printed on it.

The G-code view

This is the file itself, with line numbers, rendered from your local copy and never edited.

• Search for a command such as G1 or M104 and use Find next to walk through the matches.
• Jump to line takes a line number and scrolls straight to it.
• Click a line to select it, then Copy line to put it on the clipboard.
• Show in 2D draws the path that line produces, if it produces one.

Reading the file summary

The panel beside the preview collects what the file states and what the viewer measured:

• Estimated time — the slicer's own estimate when the file contains one, otherwise a motion-based estimate calculated here.
• Filament — mass in grams and the length of filament used.
• Layers — the layer count, with the total number of lines in the file.
• Print size — the X, Y, and Z extent of the toolpath in millimetres.
• File details — the slicer that produced the file, the layer height, and the file size.

Each figure carries a small source label — Slicer, Measured, Estimated, Assumed, or Unavailable — so you can tell a number the file stated from one the viewer worked out. If the slicer embedded a preview image, it appears at the top of the panel.

When something is not shown

The viewer states what it cannot do rather than drawing an incomplete picture and calling it finished.

• If a file is within the analysis limit but too dense for a browser preview, the summary still loads and the viewport says the 3D preview was skipped. A file beyond the device's hard input limit is refused before it is read.
• Speed colors need a full path analysis, so they are unavailable on the largest files.
• The 2D view needs printable paths it can draw accurately; some files do not provide them.
• This is a viewer for 3D-printer G-code, not a CNC simulator or a machine emulator. It shows what the file describes, not what a specific printer will do with it.

For what an individual command means, see the G-code reference and the glossary.