About Diagram Tools
Your diagrams are rendered locally in your browser and never uploaded.
Your diagrams never leave your device
Every tool on Diagram Tools runs entirely in your browser. There is no backend, no server, and no upload: the diagram source you type is parsed and rendered by JavaScript running locally on your machine, and the exported PNG/SVG files are generated in memory and handed back to you. Nothing is ever transmitted over the network.
That matters because people paste proprietary architecture documents, database schemas, and internal process flows into diagram tools. Keeping every byte on-device is the privacy moat that account-based incumbents cannot offer.
How it works
Rendering uses a small in-house engine — pure deterministic string→SVG functions written for this site, no WebAssembly and no third-party rendering library. It understands a documented Mermaid-style subset (flowchart, sequence, class, ER, Gantt, mind map) plus a few friendly DSLs of its own, and every error is reported with a line number instead of a broken canvas. PNG export rasterizes the SVG locally through a canvas. Everything is enforced by a strict connect-src 'self' Content-Security-Policy, so the page physically cannot phone home.
A deliberate bonus of the pure-function engine: exports are byte-deterministic — the same source always regenerates the identical SVG file, which makes diagrams safe to commit to a repository and diff over time.
Limits & the Pro tier
The free tier exports one diagram at a time, entirely on-device. Batch exports (many diagrams → ZIP), high-resolution 2×/4× PNG exports, theme packs, and saved presets will be part of a future Pro tier — still with no upload. For now, every tool is fully functional and free.
The site is also installable as a PWA and works offline after the first load.