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Mermaid Diagram Converter

Render Mermaid code for flowcharts, sequence diagrams, ER diagrams, class diagrams, Gantt charts, and pie charts into downloadable PNG (2× Retina) or SVG. Ideal for docs and READMEs.

Why Use Mermaid Diagram Converter?

Screenshotting a draw.io or Whimsical diagram for every small design change is slow and the images drift out of sync with the code they describe. Mermaid turns a diagram into a text file you can version with Git, review in a PR, and regenerate on every build. This converter lets you iterate on the source code and preview the rendered diagram side-by-side, then export to PNG (for Slack, Notion, presentations) or SVG (for docs sites that need infinite zoom). Because GitHub, GitLab, Bitbucket, and Notion all render Mermaid natively, the source itself often doesn't need exporting at all.

How to Use Mermaid Diagram Converter

  1. Write or paste your Mermaid syntax code in the left editor panel. Use the quick examples dropdown for common diagram types.
  2. Click 'Render Diagram' to generate the visual diagram in the preview panel on the right.
  3. Download the rendered diagram as a high-resolution PNG image or scalable SVG file, or copy the SVG code directly.

Worked Examples

Deploy flow flowchart

Input
graph LR\n  A[Push to main] --> B[CI runs tests]\n  B -->|pass| C[Deploy to prod]\n  B -->|fail| D[Slack alert]
Output
Horizontal flowchart with a branch at the "tests" node showing deploy-vs-alert paths.

Use LR (left-right) when the flow is linear; TD (top-down) for taller charts.

Authentication sequence diagram

Input
sequenceDiagram\n  Client->>Auth: POST /login\n  Auth->>DB: verify credentials\n  DB-->>Auth: ok\n  Auth-->>Client: JWT
Output
Four-lane sequence with solid (sync) and dashed (return) arrows.

Great for API docs — reviewers can edit text in a PR rather than attaching a new screenshot.

ER diagram for a new table

Input
erDiagram\n  USER ||--o{ ORDER : places\n  ORDER ||--|{ LINE_ITEM : contains
Output
ER diagram with relationship cardinalities rendered as crow's feet.

Commit the .mmd file next to the migration SQL so schema and diagram can't drift.

About Mermaid Diagram Converter

The Mermaid Diagram Converter transforms Mermaid syntax code into beautiful, downloadable diagrams. Mermaid is a powerful 'diagrams as code' tool that lets you create flowcharts, sequence diagrams, class diagrams, state diagrams, Gantt charts, pie charts, and more — all from simple text descriptions. This is the preferred approach for technical documentation because diagrams can be version-controlled with Git, reviewed in pull requests, and maintained alongside code. Our converter renders your Mermaid code into SVG diagrams in real-time, and lets you download them as high-resolution PNG images (2x resolution for Retina displays) or scalable SVG files for use in documentation, presentations, README files, and wikis. Quick example templates help you get started with each diagram type.

Troubleshooting & Common Issues

"Parse error" on a valid-looking diagram

Mermaid is whitespace-sensitive and picky about special characters. Wrap node labels that contain spaces, parentheses, or quotes in double quotes: `A["My Node"]`. Escape `%` in text labels; they're reserved for comment syntax.

Exported PNG is too small or pixelated

Our PNG export uses 2x resolution by default, which is enough for Retina but may still look soft in 4K presentations. Export as SVG and embed that instead — it stays crisp at any zoom level. If you must use PNG, scale up the source container in CSS before export.

GitHub renders Mermaid differently from this preview

GitHub is usually one or two Mermaid versions behind the latest release. Stick to stable features (flowchart, sequence, class, ER, Gantt, pie) and avoid experimental diagram types for docs that must render on GitHub. Preview here first to confirm syntax, then paste into a fenced `mermaid` code block.

Diagram gets cut off at the right edge

Long node labels can push the diagram past the canvas. Break the label with `<br>` (supported in Mermaid 8.14+) or shorten the text. For sequence diagrams, increase the default `mirrorActors` setting in the config header.

Frequently Asked Questions

What diagram types does Mermaid support?

Mermaid supports flowcharts (graph TD/LR), sequence diagrams, class diagrams, state diagrams, entity-relationship diagrams, Gantt charts, pie charts, user journey maps, and Git graphs. Our tool supports all Mermaid diagram types.

Should I download PNG or SVG?

SVG is scalable and looks sharp at any size — ideal for documentation, wikis, and web pages. PNG is a raster format better for presentations, emails, and chat messages. Our PNG export uses 2x resolution for crisp display on Retina screens.

Can I use Mermaid diagrams in GitHub?

Yes! GitHub natively supports Mermaid diagrams in Markdown files. Just wrap your Mermaid code in a code block with the 'mermaid' language identifier. Our tool is perfect for previewing diagrams before committing.

What is 'Diagrams as Code'?

Diagrams as Code is the practice of defining diagrams using text/code instead of visual drag-and-drop editors. Benefits include version control, code review, automation, and consistency. Mermaid is the most popular tool for this approach.

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