How to compare two texts
- Paste the earlier version into Original text on the left and the newer one into Changed text on the right. The colour-coded diff renders live in the panel below as you type.
- Read the result: lines prefixed with
-and shaded red were removed, lines prefixed with+and shaded green were added, and plain lines are identical in both versions. - Toggle Ignore whitespace to hide differences that are only spacing or indentation, and Ignore case to treat capitalization as irrelevant. Use Sample to load an example or Clear to empty both panes.
Eyeballing two versions of the same document is how quiet changes slip through. A single flipped number in a contract, a toggled flag in a config file, one reworded sentence in a redlined draft, the human eye glides right over them. A line diff makes each change explicit and colour-coded, so nothing hides. That is why proofreaders, paralegals, editors and developers all keep a diff tool within reach: it turns "did anything change?" into a definite answer in seconds.
The scenarios pile up quickly. A developer compares a working config against a broken one to find the line that broke a deploy. An editor checks a writer's revision against the version they signed off on. A contracts manager pins down exactly which clauses counsel altered. And more and more often, people paste a draft against its AI-rewritten version to see precisely what a model changed before they accept it. Because everything runs on your own device, these are all comparisons you can safely make without uploading a word.
What line diffing catches, and how to get the cleanest result
This tool works at the granularity of whole lines: if a line changed at all, it appears once as removed and once as added. That is exactly what you want for code, configuration and any text with one item per line, because each edit maps to a tidy pair of red and green lines. It is less flattering to long, flowing paragraphs, change one word and the entire paragraph flags as replaced. The fix is simple: put a line break after each sentence before comparing, so an edit lights up only the sentence that moved. Formatting both sides the same way first, indenting consistently, or beautifying JSON on each side, removes cosmetic differences so the diff shows only changes that actually matter.
Frequently asked questions
How does the diff checker compare texts?
Line by line, using the same longest-common-subsequence approach as git and classic diff tools. It finds the longest run of lines both versions share, then marks everything outside it: removed lines red with a minus, added lines green with a plus, unchanged lines plain.
Can I ignore whitespace or capitalization differences?
Yes. Ignore whitespace treats lines that differ only in spacing or indentation as identical; Ignore case treats Hello and hello as the same. Both filter out reformatting noise so only real edits show.
Does it compare line by line or word by word?
At the line level: a line that changed at all shows as one line removed and one added. That suits code, config and paragraph-per-line prose. For long flowing paragraphs, press Enter after each sentence so a small edit does not flag the whole block.
Is it safe to paste confidential documents?
Yes. The comparison runs entirely in your browser, nothing you paste is transmitted, logged or stored anywhere, which makes it safe for contracts, source code and unpublished writing.
Can I diff code, JSON or Markdown?
Yes. Any plain text works, including source code, JSON, YAML, CSV, Markdown and logs. Beautifying a file the same way on both sides, for example running JSON through our JSON Formatter first, gives the cleanest diff.
How large can the texts be?
Around 2,000 lines per side compares instantly. Beyond that the tool asks you to trim rather than freeze your tab.