Use this free online G-Code Viewer and Printability Analyzer to inspect sliced 3D-printing toolpaths, individual layers, extrusion, travel movements, speeds and potential print issues before sending a job to your printer.
A G-code viewer visualises the machine instructions produced by slicing software, including layer paths, extrusion moves, travel moves and other printing commands.
Yes. The NS3D G-Code Viewer opens supported .gcode and .gc files directly in a modern browser without requiring slicer software or an account.
No. Supported G-code files are processed locally in your browser and do not need to be uploaded to NS3D.
Yes. Use the layer control to display a selected layer or the complete toolpath, and switch colour modes to inspect movement type, print speed or layer.
The analyser reviews supported commands for travel efficiency, print speed, retractions, layer consistency, first-layer behaviour, temperatures, overhang risk and toolpath complexity.
No. The score is a screening aid based on the commands available in the file. Printer condition, material, calibration, adhesion and slicer settings can still affect the result.
The viewer supports common text-based .gcode and .gc files produced for FDM-style 3D-printing workflows. Results can vary when firmware-specific or non-printing commands are used.
Choose a .gcode or .gc file, or drag it into the central viewport. Rotate the model, zoom into critical regions and use Reset View to frame the complete toolpath again. Supported files are processed locally in your browser.
Toggle extrusion paths and travel movements independently. Long or repeated travel moves can increase print time and may contribute to stringing, while unexpected gaps in extrusion can reveal slicing or model problems.
Use the layer slider to isolate a layer or show the complete print. Movement Type distinguishes extrusion from travel, Print Speed highlights speed changes, and Layer helps identify where individual slices begin and end.
The information and issue panels summarise supported commands, while the score provides a quick screening result. Treat it as guidance rather than a print guarantee: printer calibration, nozzle condition, build-plate adhesion, material quality and firmware behaviour remain important.
Firmware commands and supported parameters vary between machines. For a useful technical reference, see the official Marlin G-code documentation.
If layers are missing or toolpaths look incorrect, inspect the source mesh in the STL Viewer. Use STL Repair for holes, non-manifold edges or other mesh faults, then slice the corrected model again.
Compare suitable materials on the Materials page, review manufacturing examples in Case Studies, or contact NS3D for 3D-printing support.