diagrams.net / draw.io
freeApache 2.0 canvas-based diagramming
No Enterprise gating. Browser + desktop, no signup. Go-to for architecture sketches, C4.
| URL | https://app.diagrams.net |
| Tier | free |
| Relevance | medium |
| Last active signal | v30.0.4 2026-05-27 |
| Verified alive | yes |
| Category | Tools |