Nothing is uploaded. Just open it and start.
Free, no sign-up, no credit card, no trial. No watermark on your diagram — write Mermaid, watch it render live, and ship the result as a PNG in your docs, an SVG in your designs, or a link in your team chat.
The diagram re-renders as you type, with errors pinpointed on the exact line — never lose a working diagram to a typo.
One click for a sharp PNG (1×, 2× or 4×), an infinitely scalable SVG with your diagram's fonts embedded, or a one-page PDF. Pick the theme and background, or copy it as a Markdown block or an HTML embed.
Copy a link that holds your whole diagram in the URL. Nothing is uploaded, and whoever opens it gets their own editable copy.
The editor and your diagrams re-theme together. Follows your system by default.
Your diagrams autosave in your browser as named files you can rename, duplicate and delete. They are plain Mermaid text: open or drop .mmd and Markdown files, and take them anywhere.
17 annotated examples — flowcharts, sequence diagrams, Gantt charts, and more.
Format, validate, minify and repair JSON, browse it as a tree, query it with JSONPath, and check it against a schema.
Pick colors and convert HEX, RGB, HSL and OKLCH, check WCAG contrast, build palettes, and grab a color from an image.
Compare two code snippets or files with a clear, color-coded diff, side-by-side or unified.
Compare two JSON documents by structure — added, removed and changed values at their paths, ignoring key order and formatting, with arrays matched by id. Export as JSON Patch.
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