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Try buildzr in your browser

Edit the Python model and press Run.

Good to know

  • Your code runs in this browser tab. Nothing you type is sent to a server. It runs with the permissions of this page, so run code you wrote or read, never code a stranger asked you to paste. The demo never runs code on its own.
  • A run ends after 30 seconds. Press Stop (or Esc) to end it sooner. Press Ctrl+Enter (Cmd+Enter on a Mac) to run.
  • You get the viewer and the model JSON, not Java-based exports. PlantUML, SVG and PNG export need Java, so use Copy model JSON here and export locally for the rest.
  • Python has only the standard library and buildzr. If your code creates several workspaces, the last one is drawn.
How it works
  • Python runs in a Web Worker through Pyodide, so the page stays responsive. buildzr builds the workspace as buildzr build does, and the viewer is the one buildzr serve shows. Without a Web Worker the demo does not run, because it could not stop a runaway loop.
  • The first run downloads about 6 MB (Python from cdn.jsdelivr.net, the viewer from this site). Your browser keeps them, so later runs are fast. Offline, you can keep editing, but you need one online run first.
  • Your code is kept in this browser’s local storage, so a reload does not lose it. Reset returns to the example you loaded last.
  • When you run again, the viewer keeps your place. A line such as # focus: shop/api or # focus: view:production picks where it opens the first time; see Viewer links.
  • Code is limited to 50,000 characters and printed output to 20,000. The editor is plain text, so type spaces to indent and press Tab to move on.