techdiagrams.net — the architecture diagram editor where diagrams run

techdiagrams.net is a free online architecture diagram editor. Draw system designs on a fast canvas with 112+ component icons plus official AWS, Azure, Google Cloud and Kubernetes icon packs — or describe your system in plain language and let the AI design copilot draft it as real, editable diagrams. Then go beyond pictures: attach behavior contracts and simulate load, crashes and failures against your design before you build it.

• Open the editor — free forever, no login required, local-first (your diagrams stay in your browser)
• 50 architecture templates — payment systems, event-driven backends, Raft clusters, RAG platforms — each importable as an editable diagram
• Engineering blog — distributed-systems deep dives, each with an importable diagram
• Live collaboration — free; invite anyone with a link
• Deterministic verification — declare guarantees like "never charge a customer twice" and prove them against simulated crashes, timeouts and duplicate deliveries

The editor is free. Pro adds the built-in AI (no API key needed), the real-run lab, and read-only share links.