Text Diff Tool

Paste two blocks of text and see exactly what changed — additions in green, deletions in red, everything else left alone. Same idea as git diff, minus the git repo, for the moments when you just have two blobs of text and need to know what's different between them.

Where this earns its keep

• Comparing a config file before and after someone "just made a small change"
• Checking a Terraform plan output against what you expected before you apply it
• Diffing two versions of a Kubernetes manifest when a deploy behaves differently than the last one
• Confirming a copy-pasted document actually matches the source, character for character
• Reviewing a script someone sent you without wanting to clone a whole repo just to run git diff

What's actually happening under the hood

This uses the Longest Common Subsequence algorithm — the same core idea behind git diff and Unix diff — to find the smallest possible set of changes between the two inputs, rather than just flagging every line as different the moment anything shifts position. That's why inserting one line near the top of a long file doesn't turn the whole rest of the diff red; the algorithm recognises that everything after it is still the same content, just shifted down.

A quick sanity check habit

Whitespace-only differences are the most annoying false positive in any diff tool — a file re-saved with trailing spaces stripped, or tabs swapped for spaces by an editor's autoformat, will show as "different" even though nothing meaningful changed. If a diff looks suspiciously noisy for a change you know was small, that's usually the first thing to check before assuming something's actually wrong.