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 before/after 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. The general job is any before/after text or code — AI rewrites are one common example, not the only one.

How

The homepage embeds Monaco’s Diff Editor (the same engine family as VS Code). Paste original on the left, updated on the right. 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 for teammate edits, config drift, prose drafts, or a rewrite 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.