diagram-as-code

Free online Mermaid diagram editor

Write flowcharts, sequence, ER, Gantt & class diagrams as text — render live, export clean SVG or PNG. 100% in your browser. No upload. No signup.

Open the editor Flowchart · Sequence · ER · Gantt · Class · optional AI

code7 lines

flowchart TD
    A([Start]) --> B{Input valid?}
    B -- Yes --> C[Process data]
    B -- No --> D[Show error]
    C --> E[(Save result)]
    D --> F([End])
    E --> F

previewready100%

Drop a .mmd file or start typing

Live preview renders as you type. Pick a template above to begin.

private

Rendering, validation, and export run client-side — your source is never uploaded and works offline once loaded.

portable

Diagrams are plain Mermaid text. Paste into docs, commit to git, drop a .mmd file — version it like code.

optional AI

Describe a diagram in plain English and get Mermaid back. If a provider is down, the editor keeps working.