Text & Writing
Free Text Diff Checker
Compare two versions of a text and see precisely what changed.
Free to useNo sign-up requiredNo watermarkRuns in your browser
Paste an original and a revised version into the two boxes and the differences are marked immediately: green for text that was added, struck-through red for text that was removed. A running count tells you how many lines, words or characters changed.
It answers the question that is genuinely hard to do by eye - what actually changed between two drafts of a contract, two versions of a config file, or the copy you sent and the copy that came back.
How this tool works
Paste both versions
The original on the left, the changed version on the right. You can also load a .txt, .md, .json or .csv file into the first box.
Choose how closely to compare
By line suits documents, code and lists. By word suits prose, where a single reworded sentence should not mark the whole line as changed. By character suits short strings such as reference codes.
Read the result
In line mode the two number columns are the line numbers in the original and in the changed text, so you can find the change in the source document. Copy or download the marked-up comparison when you need to share it.
How it works
The two texts are split into lines, words or characters, and then matched using a shortest-edit-script comparison - the same approach version control systems use. That is what keeps unchanged text aligned, so only the genuine differences are highlighted rather than everything after the first change.
The comparison starts by skipping the identical opening and closing sections, which is why changing one word in a long document is instant rather than slow.
"Ignore capitalisation" and "ignore spacing" change only how the texts are compared, never how they are displayed. Your original spacing and capitalisation are always shown in the result.
Line endings are normalised first, so the same file saved on Windows and on a Mac does not report every line as changed when only the invisible line endings differ.
Everything runs in your browser as you type. Neither version is uploaded, which is what makes it safe to paste a draft contract or anything else confidential.
Which comparison mode to use
| By line | Code, config files, CSV data, numbered lists, legal clauses |
|---|---|
| By word | Articles, emails, marketing copy and any edited prose |
| By character | Reference numbers, IDs, hashes, short strings |
When two texts share almost nothing
If the two texts have very little in common, there is no useful way to line them up - every possible pairing is as bad as every other. Rather than spending a long time producing an unreadable result, the tool reports the block as replaced and tells you it has done so.
If you see that notice and expected a close match, check that the two boxes are the right way round and that you have not pasted two unrelated documents.
Worked examples
Checking a returned contract
Paste the version you sent and the version that came back. Line mode shows exactly which clauses were altered, with the line numbers to find them in the original file.
Reviewing an edited paragraph
Word mode marks just the words that changed, so a sentence that had two words swapped does not appear as a whole rewritten paragraph.
Comparing two reference codes
Character mode pinpoints the single digit that differs between two long IDs - the kind of mistake that is almost invisible when reading.
Frequently asked questions
Is this text diff checker free?
Yes, free with no sign-up and no limit on how many comparisons you run.
Is my text sent anywhere?
No. Your text never leaves your device. Everything is processed by your browser as you type, so nothing is uploaded, stored or logged - which matters when the text is a draft, a contract or anything confidential.
What do the colours mean?
Green marks text that appears only in the changed version, so it was added. Struck-through red marks text that appears only in the original, so it was removed. Anything left unmarked is identical in both.
What is the difference between comparing by line and by word?
By line, any line that is not character-for-character identical is shown as one removal plus one addition. By word, only the words that actually changed are marked, which reads far better for prose. Use line mode for code and word mode for writing.
Can it compare two files?
You can load a text file into the first box with the "Load a file" button, and paste the other version into the second. It handles plain text formats such as .txt, .md, .json and .csv. For two PDF files, use Compare PDFs instead; for two Excel spreadsheets, use Compare Spreadsheets - both compare the real file directly rather than needing it converted to text first.
Does it work with other languages and emoji?
Yes. Text is compared by character rather than by byte, so accented letters, non-Latin scripts and emoji are each treated as a single character and are never broken apart in the result.