Browser-side validation

Free Mermaid Syntax Checker

Validate Mermaid diagrams in your browser before adding them to GitHub, Obsidian, docs, or slide decks. Paste code, see parser feedback, then export valid diagrams.

No signup · No upload for the core check · Works with AI-generated Mermaid code · Independent tool

Paste Mermaid code to validate

Replace the sample, load an example, or paste AI-generated Mermaid code.

Auto-checks after you stop typing. No upload, no account, no diagram-content tracking.

flowchart LR
  A(Write) --> B(Preview)
  B --> C(Export)
  B --> D(Docs Asset)

Common Mermaid syntax problems

AI-generated diagrams often mix Mermaid versions, unsupported arrows, or labels that need quotes.

GitHub, Obsidian, and documentation tools may run different Mermaid versions, so parser behavior can vary.

Once the diagram is valid, use the embedded exporter or the main Mermaid converter.

FAQ

Is this Mermaid to PNG converter free?

Yes. The core tool lets you export PNG, JPG, WebP, SVG, and PDF without signup or watermark. Future paid features may focus on batch workflows, API access, or advanced export automation.

Does my Mermaid code get uploaded?

For the core editor and export workflow, Mermaid code is processed locally in your browser and is not uploaded to our server.

Can I export with a transparent background?

Yes. Choose Transparent in the export style settings, then download PNG or WebP for slides, docs, and design tools.

How high can I export?

The free tool supports 1x, 2x, and 4x image/PDF export. Higher scales may be added later for Pro workflows if browser memory allows.

Is this affiliated with Mermaid.js or Mermaid Chart?

No. This is an independent tool and is not affiliated with Mermaid.js, Mermaid Chart, or their maintainers.