Visimer – open-source visual editor for Mermaid diagrams
Hi HN, Nick here, founder at OpenKnowledge. We built an open source library, Visimer, for editing Mermaid diagrams with a what-you-see-is-what-you-get visual editor. Try the playground at https://visimer.com/playground. You can rename labels, change shapes, add new nodes, etc. by clicking and dragging the visual canvas. We set out to build this originally for OpenKnowledge, our markdown wysiwyg editor, then realized it’d be great to share it as a proper embeddable component library so that other apps can leverage it as well. Our general take is that AI is great for generating…
In plain words
Visimer is an open-source visual editor that allows users to edit Mermaid diagrams through a what-you-see-is-what-you-get interface. Instead of manually writing syntax, users can rename labels, change shapes, and add nodes by clicking and dragging directly on the rendered diagram. It's designed for developers and applications that need to let users refine AI-generated diagrams or create visual documentation without learning Mermaid syntax. Available as an embeddable component library that can be integrated into other applications.
written from the facts on this page · September 2026
From the sources
Visual editing for Mermaid diagrams. Contribute to inkeep/visimer development by creating an account on GitHub.
Visimer brings "what you see is what you get" editability to Mermaid diagrams. Rename labels, change shapes, add new nodes, etc. by live editing the rendered diagram. AI is great for generating Mermaid diagrams that help explain concepts visually. We wanted to make it easy to edit fine details visually without digging into Mermaid syntax. Read the launch post for the story and a live editable diagram. npm i @visimer/core @visimer/dom mermaid import mermaid from 'mermaid' import { MermaidWysiwygEditor } from '@visimer/core' import { MermaidCanvasView } from '@visimer/dom' const editor = new MermaidWysiwygEditor ( { code : 'flowchart TD\n A[Start] --> B{OK?}\n B -->|yes| C[Ship]' , } ) new…from github.com
In the maker’s words, at launch
Hi HN, Nick here, founder at OpenKnowledge. We built an open source library, Visimer, for editing Mermaid diagrams with a what-you-see-is-what-you-get visual editor. Try the playground at https://visimer.com/playground. You can rename labels, change shapes, add new nodes, etc. by clicking and dragging the visual canvas. We set out to build this originally for OpenKnowledge, our markdown wysiwyg editor, then realized it’d be great to share it as a proper embeddable component library so that other apps can leverage it as well. Our general take is that AI is great for generating content, but whenever you want to tweak fine details, for example to create an artifact sharable with others, point-edit functionality is much better. We built Visimer to bring that to Mermaid diagrams, just like we did for markdown. Some technical bits: - Leverages the native Mermaid.js renderer for visualizing the Mermaid diagram true to how it’s intended. We add point-edit functionality on top. - We tried re-generating the entire file on every edit, but found that it would eat comments and formatting, etc. The final approach maps the rendered SVG elements back to a CST, so we can then edit only the parts of the file that should change. You can pair the visual editor with any text-editor so you can have both visual and code-level editor experiences. The library provides bindings for Monaco and CodeMirror and is extensible. There's also a low-level headless version. If you just care about being able to edit your Mermaid diagrams in your markdown, you can try it in the OpenKnowledge app (our OSS markdown IDE, available as Mac/Linux/Windows apps). Let us know what you think.
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