Turn your feedback into your AI's style guide
Open any markdown file. Highlight in five colors. Write in the margins. Your annotations teach your AI how you think.
v0.2 · 5.9 MB · macOS 13+ · Free & open source
Margin reading a markdown file with highlights and margin notes
Most tools render markdown for writing. Margin renders it for reading. No toolbar, no file tree, no syntax highlighting. Just your text, set in a warm serif, with room in the margins for your thoughts.
Set like a book
Serif type, a 65-character measure, generous line-height. Your markdown files become pages worth reading slowly.
Five colors of thought
Highlight passages. Write margin notes in the gutter. Start comment threads where the text lives. Undo anything.
Nothing leaves your machine
Files stay on disk. Annotations live in a local SQLite database. No account, no cloud, no telemetry. Open the database yourself — it's just a file.
How it works
Open a file
Drag a markdown file onto Margin, use ⌘O, or double-click any .md on your Mac.
Read and mark it up
Highlight in five colors. Write margin notes. Start comment threads. Everything saves automatically.
Export your thinking
⌘⇧E exports highlights and notes as structured markdown — ready for Claude, your notes app, or a script.
Every annotation teaches your AI
When you highlight a passage and add a note, Margin captures the full context — the text, your feedback, and the surrounding paragraph. Press ⌘⇧E and it all flows into a structured corrections database at ~/.margin/corrections/. Over time, your agents learn what you care about: tone, phrasing, style, substance. No setup, no configuration. Just read and react.
{
"original_text": "We leverage AI to optimize workflows",
"notes": ["Too corporate. Say 'we use AI to save time.'"],
"extended_context": "...",
"highlight_color": "pink"
}agentation.dev gives you precision control over your design. Margin gives you precision control over your writing.
Your corrections compound
~/.margin/corrections/
It's just files on disk. Feed them to any agent that reads text.
Your corrections become your AI's style guide.
Read first. Export when you're ready.
Highlight what matters. Add notes where they belong — in the margins, next to the text. When you've finished thinking, one shortcut exports everything as structured markdown. Paste it into Claude, feed it to a script, or keep it for yourself.
# Exported from Margin ## Highlights & Notes > The best interface is the one that disappears. — **Yellow highlight** · p.12 > Local-first means your data never leaves your machine. — **Blue highlight** with note: "Core design principle" > Annotations are stored in SQLite alongside your reading history. — **Green highlight** · p.34
Works the way your Mac does
Default .md handler
Double-click any markdown file. It opens in Margin.
Raycast and Spotlight
Launch or open recent files from where you already search.
File watcher
Edit the file in another app. Margin picks up changes without reloading.
keep-local articles
Read saved articles from keep-local alongside your markdown files.
Recent changes
- Five-color highlight picker
- Undo toast for non-destructive deletion
- Sidebar groups: Today, Yesterday, This Week, Older
- Full keyboard navigation with ARIA support
- Margin note indicators in the right gutter
- Warm color palette throughout
Your reading deserves its own space
Free, open-source, and yours to keep.
Built by Sam Zoloth. Source on GitHub.