Text Diff / Compare
See exactly what changed between two versions of some text. It runs entirely in your browser, so the file never leaves your computer.
Finding the change you already know is there
Two versions of a contract. A config file before and after someone "just tweaked one thing". A page of text you edited yesterday and cannot now remember editing. Reading both side by side and hoping to spot the difference is unreliable, and the longer the text the more unreliable it gets.
Paste both in and the differences are marked: added lines green, removed lines red, unchanged lines plain. Edit either box afterwards and the comparison updates as you go.
Why the comparison is smarter than it looks
A naive comparison lines the two texts up and marks everything after the first difference as changed, which is useless — insert one line at the top and the whole document lights up.
This uses a longest-common-subsequence diff, the same method behind the diff in version-control tools. It finds the genuinely smallest set of insertions and deletions, so inserting a line marks one line, not the remaining four hundred.
The two toggles that do the real work
Ignore case and ignore whitespace change what counts as a difference without changing what is displayed. They are how you make a diff readable when something has reformatted the file — re-indented code, a tool that converted tabs to spaces, a document that changed its capitalisation convention.
Turn them on and the cosmetic churn disappears, leaving the changes that actually mean something. This runs in your browser, which is the point when the two things being compared are contracts or config.
Questions
Common questions
What does this tool do?
It compares two pieces of text and highlights the differences — lines that were added show in green, lines that were removed show in red, and unchanged lines stay plain. Useful for spotting edits between two versions of a document, config, or code.
How do I compare two texts?
Paste the first version into the Original box and the second into the Changed box, then click Compare. Once you've compared, edits to either box update the result automatically.
What's the difference between Inline and Side by side?
Inline shows one combined list with removed and added lines marked by − and +. Side by side puts the original on the left and the changed version on the right, lined up so you can read across. Pick whichever is clearer for your text.
What do 'Ignore case' and 'Ignore whitespace' do?
They change how lines are matched. Ignore case treats 'Hello' and 'hello' as the same. Ignore whitespace ignores differences in spaces and tabs. Both affect only the comparison — the text shown is unchanged — so you can hide differences you don't care about.
How does the comparison work?
It compares line by line using a longest-common-subsequence diff — the same method code tools use. That means it finds the smallest real set of additions and removals, instead of naively marking everything after the first change as different.
What does the Swap button do?
It switches the two texts — what was on the left moves to the right and vice versa — and re-compares. Handy if you pasted them in the wrong order.
Is my text private?
Completely. The comparison runs entirely on your own computer in the browser — nothing you paste is uploaded or sent anywhere. That matters when you're comparing contracts, config files, or anything sensitive.
Our own software
Dictate it instead of typing it
Hold a key, say the sentence, and the words land in whatever Windows window you were already in. Runs on your own PC — no account, no upload, nothing to renew.
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