Opening the shared document…
Write your own diagram
C4, sequence, flowchart, use case, ER or dictionary — .alab, arch-lab JSON, or Mermaid, auto-detected and rendered live. C4 nodes can be dragged on the canvas, and sequence messages and lifelines added, edited, repointed, reordered, numbered and removed on it; the other kinds lay themselves out from the text. Nothing leaves your browser. Syntax reference
How .alab, JSON and Mermaid relate
.alab is the format to write: it is what the syntax reference documents, what share links carry, and what reads cleanly in a code review. .archlab.json is the same C4 model on disk — the interchange form any other tool can read without implementing a grammar; the two are lossless twins in both directions (proved on every build), so you never have to write the JSON by hand. Mermaid is read and written too, lossily — the format toggle above the pane converts in place and states what each direction drops. Nothing you type is uploaded or stored.
Tab indents · Esc then Tab leaves the editor · syntax reference