Frequently asked questions
Everything you need to know about viewing, editing, exporting and sharing Mermaid diagrams with MermaidViewer.
General questions
What is MermaidViewer?
MermaidViewer is a free online Mermaid diagram viewer and editor. Write Mermaid code and see the diagram instantly, generate diagrams with AI, export to PNG, SVG or PDF, and share links or embeds.
Is MermaidViewer free?
Yes. The editor, live preview, exports, templates and share links are free and work without an account. A free account adds cloud saving and a daily AI quota; the Pro plan adds unlimited diagrams, higher AI limits and more version history.
Do I need to sign up?
No. Open the editor and start typing. Your work is autosaved in your browser. Sign up only if you want to save diagrams to the cloud, organise them in folders and access them from any device.
Which Mermaid diagram types are supported?
All of them: flowchart, sequence, class, state, ER, Gantt, pie, mindmap, timeline, git graph, user journey, quadrant, sankey, XY chart, requirement, C4, block, packet, kanban, architecture, radar and treemap, plus any new types in the latest Mermaid release.
How does the AI diagram generator work?
Describe the diagram you want in plain language. MermaidViewer sends the request to an AI model on our server, which writes Mermaid code that streams into the editor and renders live. You can also ask the AI to edit, fix or explain an existing diagram.
Is my diagram data private?
Diagrams you create without an account stay in your browser's local storage. Saved diagrams are private to your account unless you explicitly make them public. AI requests send the diagram text to our AI provider only when you use an AI feature.
Can I export Mermaid diagrams as images?
Yes. Export PNG at up to 3x resolution (6x on Pro) with a transparent or solid background, export a vector SVG, export a PDF, or copy the image straight to your clipboard.
Can I embed diagrams in my website or docs?
Yes. Save a diagram, make it public and copy the embed code. The iframe always shows the latest saved version, so updates appear everywhere automatically.
Does MermaidViewer work on mobile?
Yes. The editor switches to a tabbed code/preview layout on small screens, and the preview supports pinch-to-zoom and panning.
What keyboard shortcuts are available?
Ctrl/Cmd+S saves, Ctrl/Cmd+K opens AI, Ctrl/Cmd+Shift+E exports PNG, Ctrl/Cmd+/ toggles comments, Ctrl/Cmd+0 resets zoom and F toggles full-screen preview. Press ? in the editor for the full list.
How is MermaidViewer different from Mermaid Live Editor?
Both render the official Mermaid library. MermaidViewer adds AI generate/edit/fix/explain, cloud saving with folders, tags and version history, public embeds and PDF export. See our full comparison.
Can I cancel Pro at any time?
Yes. Pro is billed monthly or yearly through our payment provider and can be cancelled at any time from your account; you keep Pro until the end of the billing period.
How many AI requests do I get?
Without an account you get a few AI requests per day. A free account includes 15 per day and Pro includes 300 per day. Limits reset at midnight UTC.
What are the limits of the Free plan?
Free accounts can save up to 25 diagrams in 5 folders and keep the last 10 versions of each diagram. Editing, previewing, exporting and share links are unlimited.
How do I delete my account?
Go to Account settings and choose Delete account. Your diagrams, folders and versions are permanently removed.
Still have a question? Read the guides or the Mermaid cheat sheet.