Mermaid editor · MIT · your own model key
Mermaid won the diagrams-as-code argument years ago. Diagraff is the part that comes after: it renders in your browser, runs on your provider key with nothing added on top, and is MIT down to the last file.
Free tier: 5 diagrams, no card. Import your library from Mermaid Chart in one pass.
Show our signup flow — verify email, then log in
Now add our audit-log step after login
Generateflowchart TD A[Sign up] --> B{Verified?} B -->|Yes| C[Dashboard] B -->|No| D[Resend email] D --> B C --> E[Audit log]
Diagraff has no render server. Mermaid runs client-side, so the picture
is drawn by the browser you already have open — editing a diagram costs
one repaint, not one request. There is no queue to sit in and no worker
to warm up, and the /api/render endpoint that used to exist is
gone, with a test that keeps it gone.
SVG and PNG export are browser-side for the same reason. Mermaid itself and the icon set are served from this origin, version-pinned and cached for a year, so the first diagram of the session isn't waiting on somebody's CDN.
Measured — editor UI, headless Chromium, localhost. Not AI generation.
These are editor interactions, timed in our own UX audit. They are not a claim about how quickly a model writes Mermaid for you — that depends on the model you point us at, and we won't put a number on your provider's work.
The hosted plan is priced where this category is priced — we're not going to pretend otherwise. The interesting number is the other two rows, where the AI bill is between you and your provider and we are not in the middle of it.
Paste an Anthropic, OpenAI or OpenRouter key — OpenRouter alone puts a hundred-plus models behind one key. It is encrypted at rest with Fernet and you can remove it whenever you like.
A key you brought skips our AI quota entirely. We meter what we pay for; we don't meter what you pay for. The incumbent bills AI as credits either way.
MIT licensed. One Linux box, one Python service, SQLite or Postgres, no render sidecar to babysit. You pay your host and your model provider, and nothing to us — there is no hosted component you're quietly calling home to.
We run it, back it up and keep it patched. 1,000 diagrams, PNG export, team spaces, REST API and keys. $96 a year if you'd rather pay once.
Free tier is 5 diagrams with no card, which is fewer than the incumbent gives you. If your library is bigger than that and you don't want a subscription, take the source and the first row instead.
Every part of this is designed so that leaving is boring. That is not generosity; it is the only honest way to sell a tool you keep your thinking in.
The product is turning an idea into a picture. The syntax that gets it there is an implementation detail, and we intend to keep it one.
The data model has never been Mermaid-only: diagrams carry a language column with no constraint on it, and the engine registry, the API and the MCP tool all read from the same table. We have built multi-engine support on top of that twice — and removed it twice, on purpose, because two mediocre renderers serve you worse than one excellent one. There is a test in the suite that enforces the decision.
That's a choice we re-make rather than a limitation we're stuck with. The full argument, including what would make us do it a third time, is written down.
Read the vision →