Own product · Web app · 2026
Margin: clients point at it, the coding agent fixes it
Comment on the element
Clients click the element and leave their comment on it, without an account.
Everything recorded
Each comment stores the page, selector, browser, viewport and a screenshot.
Straight to the agent
Claude Code, Codex, Cursor and Gemini CLI read the comments through the MCP server, fix them and reply in the thread.
Starting point
Website feedback usually arrives by email, as a screenshot with a red arrow and no page, device or element. Whoever builds the site first has to work out what is meant.
Now that coding agents make most of the changes, there was no way yet for feedback to reach the agent without retyping it. That is why I built Margin.
Approach
- 01
Feedback without friction
A small widget on the preview or the live site is enough. Clients point at the element and write what they want changed.
- 02
From comment to fix
The coding agent fetches the comment with selector, device and screenshot over MCP, changes the code, replies in the thread and moves the change to review.
- 03
All on Cloudflare
Workers, D1, R2 and Access with React, Hono and the MCP SDK. Claude and ChatGPT connect with OAuth, and the product site is built with Astro.
Result
Margin has been in open beta since October 2026, from €9.99 a month. I use it in my own client work: for Nordquartier Lemwerder, the client gave both rounds of feedback right on the website, and both were done the same evening.
