C4 editor — draw architecture diagrams on a canvas

View mode

Palette

Context

People

PersonA human user of the system

Elements

Software SystemA top-level system you own

External

External SystemA system outside your control

Looking for containers? They live inside an element. Select one on the canvas and use Add containers inside in the inspector.

Drag onto the canvas, or double-click to add at the centre.

Inspector

Context diagram

Title

Description

Boundaries

No boundaries yet. A boundary is a labelled group drawn behind the elements — “Internal”, an AWS region, a trust boundary. It holds no relationships of its own.

Last updated

Select a node or relationship on the canvas to edit its properties.

arch-lab — local-first architecture documentation. C4 today; more diagram types planned.

Saves as plain text you can read. Diff it, review it, commit it. .alab syntax reference