Mermaid Editor

Edit and render Mermaid diagrams locally with self-hosted Mermaid in LocalKit. Sketch flows in your browser—diagram source is not uploaded for computation.

Interactive controls load with JavaScript. Processing stays in your browser—nothing is uploaded.

Loading tool…

How to use

  1. Open Mermaid Editor — Allow the large vendor script to load once.
  2. Edit diagram source — Write Mermaid syntax locally.
  3. Preview — See SVG render or syntax errors.
  4. Download SVG — Export or copy source.

Limits

Requires JavaScript. Extremely large inputs may slow the browser tab. Results depend on your browser APIs; there is no server-side processing quota because nothing is uploaded.

When to use

When you want a quick, free utility without creating an account or sending content to an online converter.

When not to use

When you need server-side integration, batch automation at scale, or certified compliance tooling.

Privacy note

Tool inputs are processed in your browser only. Theme, language and favorites may use localStorage; hosting may keep standard access logs (IP, UA, URL) without tool payloads.

FAQ（5）

CDN Mermaid?

No—mermaid.min.js is self-hosted and loaded only on this tool page (~2.5MB).

Uploaded diagrams?

Source never leaves the browser.

Export?

Download SVG; Copy typically copies the Mermaid source.

Syntax errors?

The preview shows the parser/render error message.

PlantUML server?

Not used—no remote renderers.