Show HN: Merview – OSS Mermaid and Markdown Editor and Viewer

Hi, I'm Mick.

This is a side project I built over the last couple months. We've been using it internally at as we've been building http://dollhousemcp.com to view all the markdown documents with Mermaid diagrams that AI tools love to generate. They're all quite good at building these diagrams. It's a great way to visualize workflow for complex systems, but I couldn't find a good way to render them locally.

GitHub renders them fine, but only after you push. The VS Code extensions for inline Mermaid rendering weren't intuitive and broke on my system several times. The various online tools want you to create accounts, hand over login credentials, connect to services, and often have limitations. That was enough friction for me to just build my own. And, it turns one month old this Saturday.

I wanted simple: drop a markdown file in, see it rendered with working diagrams. No login, no setup.

What it does:

  - Renders markdown with full Mermaid diagrams (flowcharts, sequence diagrams, ER diagrams, state machines, etc.)                                                                                                
  - Drag-and-drop or paste markdown directly
  - Load a file from the drop down
  - Load a remote files by pasting in a URL or link directly with a parameter (?url=path/to/file.md)
  - Double-click and zoom in on diagrams for fullscreen view
  - Mermaid snippet dropdown (Ctrl/Cmd+M) for quick diagram insertion / edits
  - Lots of theming: 
    - Markdown syntax highlighting
    - Markdown preview
    - Code syntax highlighting
    - Mermaid diagram theming
  - Upload custom CSS for complete styling control
  - Print/PDF export
    - Use horizontal rules for visible page breaks in a PDF print (I use this for quick slide decks)

Self-eating dogfood – the homepage and all documentation are markdown files rendered by Merview itself.

It's entirely client-side, no backend, no tracking. Clone it and run it locally or host it yourself.

I also worked hard to make sure it has robust safety, and significant tests for my benefit and anyone else modifying it.

It is AGPL-3.0 licensed, so anyone can use it, and modifications can make their way back into the Open Source community. If you have issues, notes, comments, requests, please feel free to add them to the repo.

I know it still has rough spots, but I am proud of it, and wanted to show it off.

Curious what folks think, and happy to answer questions.