About Mermaid Viewer

Mermaid Viewer is a free online editor and viewer for Mermaid diagrams, built for the way people actually work on phones as much as laptops. Paste code, see the diagram instantly, pinch and drag to explore it, then export an image or share a link.

Why we built it

Existing Mermaid editors were designed for desktop first. On a phone they fight the browser: zoom hijacking, tiny buttons, exports that go nowhere. We rebuilt the workflow around touch gestures, a thumb-sized syntax bar, and export paths that match each platform — including saving straight to Photos on iOS.

Privacy is the product

Everything renders locally in your browser. Your code is never uploaded, there are no accounts, and history lives only in your device's storage. Share links carry the diagram inside the URL itself — nothing is stored on our servers. Read the full privacy policy.

What's inside

• Syntax guides for all 12 core diagram types
• 50 ready-to-edit templates across those types
• A printable syntax cheatsheet with error fixes
• Honest comparisons with draw.io, Lucidchart, PlantUML and Visio

Credits

Rendering is powered by the open-source Mermaid project. Mermaid Viewer is an independent tool and is not affiliated with the Mermaid.js project.