Getting started

Cold Crabby turns a 3D model into G-code — the file your printer actually reads. Drop in an STL, pick your printer, press Slice, send it off.

This page gets you from nothing to a printable file. Everything else in this section is detail you can come back for.

1. Pick where it runs

You don't have to install anything to try it. Pick whichever fits how you print.

	Best for	What you do
In your browser	Trying it out, tablets, locked-down machines	Open slicer.maxscopp.de
Desktop app	Everyday printing on a laptop or workstation	Install the macOS, Windows or Linux build
iPad	Slicing on the couch, with touch and pen	Build it yourself for now — see Building
Your own server	A team, a workshop, a print farm	See For teams

All four behave the same. The slicing engine is literally the same code, so a model sliced in the browser and the same model sliced on the desktop give you the same G-code.

Which should I pick?

Start in the browser. If you like it, install the desktop app — it's quicker on big models and can reach printers on your network without browser security getting in the way.

Advanced — what actually differs between them

The browser build compiles the whole pipeline to WebAssembly and never uploads your model anywhere. The desktop app runs the same pipeline as native code, with OS file dialogs, native menus, and a direct network path to your printer (no CORS). A self-hosted server slices server-side and streams progress back over a WebSocket. Only the transport differs — the geometry does not.

2. Open a model

The home screen gives you three ways in:

• Try the 3DBenchy demo — a model is already loaded, nothing to find on disk.
• Open Model to Slice — pick a file and go straight to the build plate.
• Empty Workplate — start with a bare bed and add models yourself.

You can also just drag a file onto the window at any time.

Supported formats: .stl, .obj, .3mf, up to 500 MB each. A 3MF holding several parts is split into one object per part, so you can move them independently.

New models land on the bed and are turned onto their flattest face automatically. Both behaviours can be switched off — see The build plate.

3. Check printer and filament

The settings panel on the left has three tabs:

• Printer — the machine: bed size, nozzle, firmware.
• Filament — the spool: temperatures, cooling.
• Process — how to print it: layer height, walls, infill, supports.

Each tab has a dropdown at the top for picking a saved profile. Cold Crabby ships with sensible defaults, so for a first slice you can usually leave everything alone.

If your printer isn't set up yet, go to Settings → Printers → Add printer. For a Klipper machine on your network, paste its address and press Detect — bed size, nozzle and firmware fill themselves in. Details in Printers, filaments and profiles.

4. Slice

Press Slice, bottom right. A progress bar walks through the stages ("Slicing layers", "Generating walls", …) and finishes with something like Sliced · 218 layers · 1h 12m.

The view flips to the G-code preview so you can check the result before you commit plastic to it. Drag the layer slider, or press ↑ and ↓, to walk up through the print. See Reading the preview.

5. Send it to the printer

Bottom right again, the result button offers three things:

• Download G-code — save the .gcode file and copy it across yourself.
• Just upload — put the file on the printer without starting it.
• Upload & print — send it and start immediately.

Upload and print need a connected printer. Today that means Klipper via Moonraker (Mainsail, Fluidd). Other connection types can be saved but won't send yet. See Sending to your printer.

Where to next

• The interface — what every panel and button does
• The build plate — moving, rotating, duplicating, arranging
• Print settings — what the options mean, in plain language
• Keyboard shortcuts — the whole list
• Troubleshooting — when something looks wrong