MdNotes – Local Markdown Notes with Native Mermaid Diagrams

MdNotes is now public, and the first prebuilt downloads are out with release v0.1.1.

It’s a small, local, Obsidian-style notes app for Windows, macOS and Linux. You point it at a folder (the “vault”) and every note is just a plain .md file in that folder.

MdNotes

The Idea

A lot of note apps keep your notes in a database, a cloud account or a format only that app understands. MdNotes is built on three simple rules:

Your notes are plain files. Open them in any editor, put them in git, sync them however you like.
Nothing leaves your machine. No account, no cloud and no telemetry.
No embedded browser. The preview isn’t a web page. Markdown is parsed with Markdig and drawn as native controls, so the app stays light.

Mermaid, Drawn Natively

Mermaid diagrams are usually rendered with JavaScript in a browser. MdNotes draws them natively instead: flowchart, sequence, class, state, ER, gantt, pie, mindmap and more. You write the diagram in a code block and it shows up in the preview, with no web view involved.

What It Can Do

Edit, split and reading views (Ctrl+E) with a live preview
[[Wikilinks]] to notes and [[Folder/]] links to folders. Clicking a link to a note that doesn’t exist yet creates it.
Quick switcher (Ctrl+O) and accent-insensitive full-text search
Vault-wide search and replace (Ctrl+Shift+H) with match case, whole word and regex. You can untick single matches before replacing, and undo the whole replace in one step.
Configurable autosave: after a delay, when you leave the note, or only on Ctrl+S. Useful when the vault is a git repo or a synced folder.
Note templates with {{title}}, {{date}} and {{time}} placeholders
.mdnotesignore to keep folders like node_modules out of the sidebar and search
System, light and dark themes. The sidebar also follows changes made to the folder outside the app.

Under the Hood

MdNotes is built with .NET 10 and Avalonia 12, using MVVM with CommunityToolkit.Mvvm. Markdig parses the Markdown, and Mermaid diagrams are rendered to SVG with Mermaider and drawn with Svg.Skia.

Try It

Prebuilt builds for Windows and Linux (x64) are on the MdNotes project page and on GitHub Releases. They don’t need anything else installed:

Linux: mdnotes-linux-x86_64.tar.gz, compiled ahead of time (Native AOT) for a fast start. Needs glibc 2.34 or newer.
Windows: mdnotes-windows-x86_64.exe, a single executable. There’s also an experimental Native AOT zip that starts faster. The builds aren’t signed yet, so SmartScreen may ask before the first start.
macOS: build from source with the .NET 10 SDK.

The source is on GitHub.

Notes are just text files. The app should treat them that way.