Redline

Highlights, word by word, how a page differs from the same page on another site, such as your dev server against production.

Redline shows what you changed on a website while you read it. Pair the site you are working on (say http://localhost:3000) with the site to compare it with (say your live site, or a second local server running the main branch). Then turn Redline on in a tab with the toolbar button, Alt+Shift+R, or ?redline in the address: • New words are highlighted, and removed words are struck through right where they were. • Press V to switch views: all changes, only what was added, or only what was removed. • Press J and K to jump to the next and previous change. • Review as you go: approve (A) or reject (X) each change, or add a note or suggested wording (C). The badge shows how many changes are still to review. • "Copy notes" puts all your rejections, notes and suggested wording on the clipboard as one clear list, ready to paste to a colleague or an AI assistant. • "Pages" (P) lists every page of the site that differs, including new and removed pages, with each page's review progress. It checks pages on request, a batch at a time, so it is gentle on big sites. It stays on in the tab as you click around, including in single-page apps. Sites can set it up for their visitors: a preview build with <meta name="redline" content="https://your-production-site"> needs no settings at all, just a click on the button. That works for Vercel, Netlify and Cloudflare previews, and for GitHub Pages PR previews served from a folder. Redline compares the text both servers send, so a clock or a "3 minutes ago" drawn in the browser never shows up as a change. Sites behind a login work as long as you are signed in to them. Each pair can ignore parts of the page (menus, footers, footnote numbers) with a CSS selector. Apps drawn entirely in the browser, such as micro-frontends, can be rendered before they are compared, and compared only within the app's own part of the page. Redline has no servers, analytics or accounts. It only talks to the sites you pair, and only asks for access to those. Open source: https://github.com/octagorm/redline