About CheckDiffs

Who

CheckDiffs is made by FT — a small, independent project, not a company with a team bio. There are no invented credentials here. The product is the point: a paste-first diff you can trust with real snippets.

Why

About a month or two ago I was vibe coding with Gemini. Bugs meant many versions. Each new version often changed a lot — including things that did not need changing. The chat got long; even with reminders not to touch prior work, the model would forget after a while.

I know agentic tools exist now so you do not have to paste every try into an IDE — my workflow was inefficient — but some people still work that way. I did not know how big that audience is. I just wanted a simple independent page to compare before and after.

Plenty of tools already do this, including VS Code's built-in diff. I still preferred a standalone browser page, so I bought the domain and built exactly that.

How

The homepage embeds Monaco’s Diff Editor (the same engine family as VS Code). Comparison for basic side-by-side runs in your browser. We do not upload your pasted content for that flow — open DevTools → Network if you want to verify. Language highlighting covers Plain Text, JavaScript, TypeScript, Python, HTML/CSS, SQL, and JSON. The same paste-first idea works whether the rewrite came from Gemini, ChatGPT, Claude, Cursor, Lovable, or Bolt.

What we don’t do

We are not a PDF/image/Excel suite. We do not claim a semantic JSON tree-diff, and we do not claim to beat VS Code or every other online diff tool — only to stay simple and standalone in the browser, with no account for basic compare. Basic side-by-side stays free forever; Pro ideas (export, ads-free, AI summary quota, share links) are honestly TBD — no fake checkout. If you need sixty formats or server-side document compare, a broader product may fit better.