Tiny Online Tools
The CNC G-code Viewer renders a milling or router program as a real three-dimensional toolpath, not a flat preview. Unlike a 3D-printing G-code, which mostly stacks flat horizontal layers, a milling program routinely plunges, ramps and arcs through Z within a single pass — so this viewer draws the whole path in 3D, exactly as the machine will move.
Drop in a .nc, .ngc, .tap, .gcode or .g file exported from Fusion 360, Carbide Create, VCarve, LinuxCNC or any grbl-compatible post processor. The tool distinguishes rapid moves (G0, shown as translucent blue lines) from cutting moves (G1/G2/G3), which are colored along a depth ramp — red near the top of the stock, blue at the deepest cut — so you can spot roughing versus finishing passes at a glance. Arcs (G2/G3, whether specified with I/J center offsets or an R radius) are tessellated into smooth curved segments rather than drawn as straight chords.
For multi-tool jobs, switch to "color by tool" to see exactly which tool cut which part of the path — tool changes (T words and M6) are tracked automatically. The stat panel reports total move count, cutting versus rapid travel distance, the bounding box of the cut geometry, spindle speed range (from M3/M4 S values), and the number of distinct Z-depths the program visits.
Orbit, pan and zoom with your mouse or touch; snap to isometric, top or front views, or reset the camera to frame the whole part. Toggle rapid moves and the stock bounding box on or off to declutter the view.
Everything runs locally in your browser — the file never leaves your machine, which matters for proprietary CAM output. If the program uses cutter compensation (G41/G42), the viewer shows the path exactly as programmed, and says so plainly, since applying real cutter compensation requires knowing the tool diameter the controller would use.
Pair it with the CNC Toolpath Analyzer for feed rates, machining time estimates and a full depth-per-pass breakdown.