Built a free G-code viewer with real cycle-time simulation. Try to break it.

[UltraNC]

I've built a free G-code viewer that runs in the browser. It uses real motion control algorithms the same kind as your CNC controller.

Set your machine's rapids and acceleration in the "Machine Dynamics" box to match your machine, or just leave the defaults.

Nothing is uploaded. The file is parsed in your browser and never leaves your machine, so you can paste anything.

What it handles: G0 to G3 arcs in all planes, canned cycles including peck drilling and rigid tapping, M98 / M97 / o-sub subprograms nested and expanded, dialect-aware G04 dwell (Fanuc milliseconds vs LinuxCNC seconds), G94/G95, G61/G64 blending in the time model, and optional S-curve jerk if you set it. Anything it can't fully model gets mentioned in the message panel instead of being quietly ignored.

The challenge. Throw your ugliest post-processor output at it and try to make it time wrong, draw wrong, fall over, or simulate something wrongly without telling you. A missing disclosure counts too. Find one and I'll fix it and credit you in the changelog.

The rules and the full supported-code list: https://ultranc.com/challenge/
The viewer, no signup: https://ultranc.com/gcode-viewer/

The screenshot below is the "UltraNC Sign.nc" demo, timed at 44:35. It's in the viewer's demo file menu, so load it and check the number for yourself, then bring your own worst file.

Free, no accounts, no catch. Tell me where it's wrong.

[Muzzer]

Looks nice, certainly when compared to ncviewer - which was developed by an intern almost a decade ago.

The likes of Centroid and Linuxcnc have good 3D nc viewers built in that also take account of stock dimensions, tool libraries, custom g codes, machine envelope etc.

Fusion does a pretty good job of estimating machine times and the effect of tool changes is lost in the noise for large programs.

You are very cagey about anonymity - I'd want to understand where this programming has come from (developers' background, industrial experience if any etc) and what plans to monetise this significant effort. It might be free now but why did you develop it in the first place? Can you promise it will remain free? Surely not. There is no other website, external links, imprint, author details etc.

Just as important to set the context and roadmap as it is the wow us with horny GUIs, if you want people to invest even just their time in a new workflow element.