Playground
Edit source, switch templates, preview, download and save a diagram in this browser.
Choose a language and edit its source. Selecting a template does not replace your draft until you click Apply template. Each language retains its draft and undo history during this editing session. Switching the interface language never translates existing source.
Where saves go
Save diagram writes to this site's browser storage; there is no upload service. Reloading or returning restores the last successful save. Leaving this page discards unsaved changes. Cancel restores the last saved version.
SVG / PNG downloads use the current valid preview and do not require a save. The JSON download contains the last saved source, language, title, revision and PNG. The Markdown view contains a standard fence and source, without the title or preview image.
If browser storage is disabled or full, saving fails and the draft stays open. SVG / PNG downloads remain available. This example is a single-page local host, with no cloud sync or cross-tab collaboration.
Keyboard and recovery
| Action | Shortcut |
|---|---|
| Indent / outdent | Tab / Shift-Tab |
| Leave the source pane | Esc, then Tab |
| Find / replace | Ctrl / ⌘ F |
| Undo | Ctrl / ⌘ Z |
The preview follows after a short delay. Composition must finish before rendering. Invalid, stale or pending previews cannot be saved. Correct the source or choose Refresh preview to retry without losing the original text.
See the template catalog for syntax starting points and save and restore for the host contract.