Diff / Compare
Find the differences. Like a very specific game of spot-the-difference.
What this does
diff library (same algorithm as git diff). Line, word, and character-level diffing. All client-side.
Paste two versions of something and see exactly what changed. Additions show up green, removals show up red. Unchanged lines sit there unbothered. The output is a unified diff view below the two inputs, showing everything in context.
Common use cases
Comparing API responses between versions. Hit the endpoint before and after a deploy, paste both responses, see exactly what changed in the payload.
Checking configs. Someone says they "didn't touch anything." Paste the before and after. The diff doesn't lie.
Reviewing edits to prose. Word diff mode highlights individual word changes within sentences, which is much better than line diff for documentation and content.
Verifying migrations. Paste the expected output and actual output. If the diff is empty, your migration worked.
Things to know
Three diff modes, each for different situations. Line diff compares line by line, same algorithm as git diff. Best for code and structured data. Word diff highlights individual word changes within lines, much better for prose. Character diff catches single-letter typos and transposed characters that word diff would swallow.
The Ignore Whitespace toggle strips trailing spaces, normalizes tabs vs. spaces, and collapses multiple spaces before comparing. Turn it on when comparing code that got reformatted. Whitespace differences are real, but rarely the ones you care about.
Pro tip: if your diff output is noisy, normalize the formatting first. Run both inputs through a JSON formatter or sort the lines before comparing. Diffing two unsorted lists produces chaos. Diffing two sorted lists shows you exactly what was added or removed.
Privacy
Your text stays in your browser. Nothing gets uploaded, nothing gets stored. Compare proprietary code, production configs, legal documents. We won't know, and that's the point.
Questions
What's the difference between line, word, and character diff?
Line diff compares whole lines, the way git does, and it's best for code. Word diff highlights the individual words that changed inside a line, which reads much better for prose. Character diff catches single-letter typos and transpositions the other two would skim past.
Can I compare JSON or code?
Yes. For JSON, format both sides first so the diff shows real changes instead of whitespace noise. Same idea for code that got reformatted: normalize first, then compare. Line diff with ignore-whitespace on is usually the right combo.
Does it ignore whitespace?
It can. Flip on Ignore Whitespace and it strips trailing spaces, evens out tabs versus spaces, and collapses runs of spaces before comparing. Leave it off when whitespace actually matters, like in YAML or Python.
Why is my diff so noisy?
Usually because the two sides aren't normalized. Diffing two unsorted lists or two differently-formatted blobs produces chaos. Sort the lines or run both through a formatter first, then the diff shows you only what genuinely changed.