Mermaid Viewer is a browser editor for Mermaid diagrams. Code on one side, live preview on the other, with GPT-4 turning a plain description into Mermaid syntax, syntax error detection with suggested corrections, export to SVG, PNG and PDF at chosen resolutions and themes, shareable editor links for review, and a Docker deployment with access controls for teams that cannot send diagrams to a third party.
Text-defined diagrams are the right answer for anything that lives in a repository, because they diff, review and version like code while a drawn diagram does none of those things. The genuine additions here are the AI generation – Mermaid’s syntax is easy to read and fiddly to write from memory, especially for sequence and state diagrams – and the self-hosted Docker option, which is the difference between usable and prohibited at organisations with architecture diagrams they cannot paste into a website.
The thing to weigh is what is actually being sold. Mermaid itself is open source, and GitHub, GitLab, Notion, Obsidian and VS Code all render it at no cost, as does the official live editor – the paid product here is the AI generation, the export options and the collaboration layer, not the diagrams. Judge it on those. The free tier is tight and watermarks exports: 3 diagrams and 5 AI conversations a day. Paid plans are annual only, Starter $69.99 and Pro $119.99 a year.
