Your agent publishes the finished page to a private link. You open it, mark up any line, and it revises — the way you'd scribble in the margin of a printout. No login, no copy-paste, no screenshots.
Where this fits
More and more, you're not sitting at the machine doing the work. Margin is the piece that keeps you in the loop from wherever you are.
Kick off and steer work from your phone, away from your desk. The agent runs in the cloud — but you still have to actually see what it made.
Your agent runs on the machine at home or the office while you're out. Same problem: the output lives over there, and you're over here.
Either way, there's no good way to look at a rendered document — and comment on it — from your phone. You squint at raw HTML, or ask for screenshots. Margin is that missing review surface.
What you review
You shouldn't have to read HTML source or scroll a wall of Markdown to know if it's right. Margin shows your agent's output the way it'll actually look, and you react to that.
Self-contained pages render exactly as published — reports, one-pagers, tables, landing copy.
Your agent renders Markdown to a clean page first, so you review the formatted result, not the asterisks.
Decks are even worse to review in raw form. Comment on slides & PowerPoint the same way — landing next.
How it works
You stay in your chat with your agent. Margin is just the part where you look and react.
It renders the finished work to a private Margin link and hands you the link.
Open the link, select any text, and type what you want changed. Your note sticks to that exact spot.
Say “check.” It reads your comments, updates the same page, and marks them done. Refresh to see the new version.
Get started in 60 seconds
Do step one a single time. After that it's just steps two through four, every time you want feedback.
Install it yourself, or just tell your agent to set itself up. Either way it's one paste.
Drops a small skill file into Claude Code — then it's ready in every future session.
Then open a new Claude Code session — the margin skill is ready. View the skill file →
On your phone, or running an agent remotely with no terminal handy? Paste this to your agent — it fetches the instructions and starts using Margin this session.
No install, nothing saved on your machine — handy when you're away from your desk.
Anything you'd want to eyeball before it's final — a summary, a one-pager, an email, a table. Just mention Margin:
Your agent renders it and replies with a link. Tap it.
On your phone or in a browser: select any text → tap “Comment” → say what you want. Your note anchors to that exact sentence. Leave as many as you like.
Back in your chat, type:
check
Your agent reads every comment, revises the page, and marks them resolved. Refresh the same link to see the new version. Repeat until it's right.
The complete workflow, written out — paste it into any Claude Code session once. (The skill above is the same thing, made permanent.)
What you'll see
No accounts, no app to download. The link opens in your phone's browser and works exactly like you'd expect.
The point
Margin closes the loop: your agent renders the work, you react in place, it revises. One private link, start to finish.
Trust & security
No accounts, no tracking, no shared secrets. Every document is reachable only through its own link — and the whole thing is open source, so you can run your own instance.
Each document gets a long random link scoped to that one page. A leaked link only ever exposes its own document — never your others.
No login, email, or API key. The agent self-provisions a per-document token the first time it publishes — there's nothing to sign up for.
Access rides in an HMAC-signed capability token bound to one document and role. The agent keeps a private token; you get a reviewer link. Links can be set to expire.
On open, your reviewer token moves into an httpOnly cookie and is stripped from the URL — so it's never in browser history or readable by page scripts.
Documents render in a sandbox with JavaScript disabled behind a strict content-security policy. A page can't run code, set cookies, or phone home.
Documents live in the instance's database (Vercel KV / Upstash Redis) and travel over HTTPS. Margin is MIT-licensed — self-host it and own the data end to end.
Good to know
No. No login, no API key, no sign-up. Your agent gets a private token the first time it publishes, and that's it.
Rendered HTML and Markdown today — reports, one-pagers, emails, tables, landing copy. Slides and PowerPoint are coming soon.
Yes. Each document gets an unguessable link scoped to just that page. Only people you share it with can open it.
Claude Code today — it's a downloadable skill. Any agent that can run curl can use the same HTTP API.