100% client-side — files never leave your device

G-code viewer

Open a 3D printing or CNC toolpath in your browser, scrub through it layer by layer, and check dimensions, filament use and travel moves before you run the job.

Drop a G-code file hereor click to browse — parsing happens in your browser

.gcode · .gco · .g · .nc

How it works

  1. Drop the .gcode or .nc file. Slicer output and CNC programs both work; parsing runs locally and large files never leave your device.
  2. Scrub the layer slider. Reveal the print one layer at a time to inspect infill, walls and the first layer.
  3. Check the numbers. Filament length and weight, bounding size and a rough time estimate come from the toolpath itself.

Catch problems before the printer does

Most failed prints are visible in the toolpath: a first layer that starts mid-air, a model sliced without support under an overhang, infill that never bonds to the walls, or a print that is quietly 3 mm taller than the build volume.

What to look for

Layer 1 should be a continuous, closed outline — gaps there mean a levelling or adhesion problem. Travel moves crossing open space over printed areas are stringing candidates. A sudden jump in the layer slider usually means the slicer inserted a Z hop or a vase-mode spiral rather than an error.

Filament and weight

The filament figure is the total extruded length from the E axis. The weight assumes 1.75 mm PLA at 1.24 g/cm³ — for PETG multiply by about 1.03, for ABS by 0.85, and for 2.85 mm filament the length figure stays right while the weight does not.

Before slicing

Preparing the model is the other half of the job: convert CAD with STEP to STL, inspect the mesh in the 3D viewer, and cut oversized meshes down with the mesh simplifier.

Frequently asked questions

Which slicers does it support?

Any slicer that emits standard linear moves — PrusaSlicer, Cura, Orca, Bambu Studio, Simplify3D and Slic3r all work. The parser reads G0/G1 moves plus the G90/G91, G20/G21 and M82/M83 modes, and it handles modal motion, so files that state the command once and then list bare coordinates are read in full.

Does it open CNC programs (.nc) as well as slicer output?

Yes. A .nc file from a router or mill has no extruder, so G1 feed moves are drawn as cutting passes and G0 as rapids, and the readout switches from layers and filament to Z passes and cutting moves. One real limit: circular interpolation (G2/G3) is not evaluated, so a program built from arcs will be missing those moves — the straight-line segments still show.

How accurate is the print time estimate?

It is a lower bound. The estimate integrates distance over the commanded feedrate but ignores acceleration, jerk limits and heating — real prints usually take noticeably longer. Trust your slicer’s number over this one.

What do the colours mean?

Blue lines are extrusions — actual printed plastic. Grey lines, hidden by default, are travel moves where the nozzle repositions without extruding. Turning travel on is the quickest way to spot stringing-prone paths.

Is my G-code uploaded?

No. The file is parsed and rendered entirely in your browser.

Does the viewer reconstruct a solid 3D model?

No. It draws extrusion and travel toolpaths, not the finished solid or its surface. That makes layer order and nozzle movement visible, but it is not a substitute for mesh inspection or print simulation.

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