3D Printing · G-code
G-code Viewer & Simulator
Drag in a sliced .gcode file. See the toolpath in 3D, scrub the print timeline, and check what the slicer's actually about to do before you start a 12-hour print.
Bambu Studio / PrusaSlicer / OrcaSlicer / Cura outputs all supported, arc moves included.
Why preview G-code before printing?
- Catch supports going to weird places— slicer support algorithms occasionally route under overhangs that won't actually need them, wasting filament and time.
- Verify travel routing — long travel moves across previously printed areas mean ringing / scarring; enable Show travel moves and watch the gray lines cross the model.
- Spot weird layer transitions — scrub layer-by-layer to find the layer where the print suddenly looks different (often where slicer changed strategy or hit an interface).
- Sanity-check before a 12-hour print — much cheaper than discovering at layer 200 that the model lifted off the bed at layer 3.
Print time and filament estimates are computed from the G-code itself (feedrate × distance, filament cylinder volume × density). Real-world times are typically 5–15% longer due to acceleration limits the previewer doesn't simulate.
Previewing G-code before you print
A G-code file is the list of moves your printer will actually make, so it's the last chance to catch a problem before a long print: a missing layer, supports where you didn't want them, a first layer that doesn't reach the bed. Drop the .gcode here and the toolpath is drawn in 3D — extrusion moves in colour, travel moves separately — with a slider to scrub through the print layer by layer.
The panel reads the numbers you'd want before committing a spool: estimated print time, filament length and weight, layer count and the size of the printed area, plus which slicer produced the file.
It reads output from Bambu Studio, OrcaSlicer, PrusaSlicer, SuperSlicer and Cura, including arc moves (G2/G3) written when arc fitting is turned on, relative and absolute extrusion, and the slicers' own layer markers. Binary G-code (.bgcode from newer Prusa printers) isn't supported — export plain .gcode instead.
Frequently asked questions
- How do I view a G-code file online?
- Drop the .gcode (or .gco / .g / Bambu .gcode.3mf) file into the box above. The toolpath appears in 3D straight away — drag to rotate, scroll to zoom, and use the slider to step through the layers. Nothing is uploaded.
- Is this G-code viewer free?
- Yes. Free, no signup and no file limit — it runs entirely in your browser.
- Can it open Bambu Lab and OrcaSlicer G-code?
- Yes — plain .gcode and Bambu's sliced .gcode.3mf (File → Export → Export plate sliced file) both open; for a multi-plate file the first plate is shown. Arc moves (G2/G3) from arc fitting are drawn as arcs. An unsliced .3mf project has no G-code yet — open it in the 3MF Viewer instead.
- How accurate is the print time estimate?
- It's computed from the moves and their feed rates, without the printer's acceleration and jerk limits, so it usually reads shorter than the slicer's own estimate. Use it to compare files, and the slicer's number for planning.
- Can it convert G-code back to STL?
- No. G-code holds the nozzle path, not the model's surface, so turning it back into a solid is only an approximation. Keep the original STL or 3MF — or open it in the STL viewer.
- What about .bgcode files?
- Binary G-code from Prusa's newer printers isn't supported yet. In PrusaSlicer, turn off binary G-code in Printer Settings → General, or export plain .gcode.
- Is my G-code uploaded anywhere?
- No. The file is parsed and drawn on your own device.