How to Compare Two Texts and Find the Differences (Diff Checker)

Which version is newer? What did the other person change in the contract? Did anyone alter the figures in the email? Reading two long texts side by side to spot differences is slow and error prone. A diff checker does it in a second, and the free Text Diff Checker is built for exactly that.

Quick answer

Paste the original text in one box and the changed text in the other, and choose line-by-line or word-by-word comparison. Added parts are shown in green and removed parts in red and crossed out. Nothing is uploaded.

When it is useful

• Contracts and agreements. Find the quiet changes between two drafts.
• Essays and articles. See what an editor altered.
• Emails and messages. Check what was added or removed in a forwarded version.
• Code and configuration. See what changed between two files.
• Translations and notes. Compare versions over time.

Line by line or word by word?

• Line by line is best for code, lists and structured text, where a whole line changes.
• Word by word is best for prose and small edits inside a paragraph, such as a changed number or a different adjective.

Choose the mode that matches how the text was edited.

How to compare, step by step

1. Open the Text Diff Checker.
2. Paste the original text in the first box.
3. Paste the changed text in the second box.
4. Choose line by line or word by word.
5. Read the result: green for added, red and crossed out for removed.

Reading the result

• Green shows text that exists only in the new version.
• Red, crossed out, shows text that exists only in the original.
• Unmarked text is the same in both.

Go through the highlighted parts one by one and decide whether each change is acceptable.

Comparing PDFs and Word files

This tool compares pasted text. For PDFs, you can use Compare PDF, which marks removed words in red and added words in green in one result document. For Word files, copy the text of both versions into the diff checker, or convert them with Word to Text first.

Tips for accurate comparison

• Paste plain text rather than formatted text to avoid noise from invisible formatting.
• Remove extra spaces and blank lines with Remove Duplicate Lines if they cause false differences.
• Check numbers and dates carefully. Small changes there are often the most important.
• Keep both versions until you have confirmed the changes.

Privacy

Nothing is uploaded. The comparison runs in your browser, which makes it suitable for private drafts and agreements.

Use cases in more detail

Reviewing contracts

Legal and commercial documents are often revised several times. Paste the old and new clauses and read only the highlighted changes: new obligations in green, removed protections in red. Always have a qualified person review anything important.

Proofreading and editing

Writers can compare their draft with the editor's version to see exactly what was changed and to accept or reject each edit.

Checking copied content

If you suspect that two documents are almost the same, a diff shows where they differ. This is useful in teaching and in checking that a translation or a form letter follows the original.

Code and configuration

Developers compare versions of a script or settings file to find which line caused a problem.

Tips for cleaner comparisons

• Paste both texts in the same format. One with line breaks and one without will look completely different.
• Normalise spaces with Find and Replace when double spaces cause noise.
• Sort lists first with Remove Duplicate Lines if order is not important.
• Compare small parts of long documents, section by section.
• Use word mode for prose and line mode for lists and code.

Limits

A diff checker shows differences, not meaning. A single changed word, such as "may" to "must", can change the whole sense of a sentence, so read each highlighted change with care. It also does not understand moved paragraphs; a moved block shows as removed in one place and added in another.

Privacy and trust

The comparison runs in your browser and nothing is uploaded, so you can compare confidential drafts. Still, remember to close the page on shared computers afterwards.

Quick checklist

1. Paste the old and new text.
2. Choose line or word mode.
3. Review every highlighted change.
4. Keep both versions.

A worked example: reviewing a revised rental agreement

A landlord sends back a revised agreement with the message "just small changes". The tenant pastes the old clauses on the left and the new ones on the right, and chooses word-by-word mode. The result shows that the monthly service charge has risen by 500, the notice period has changed from 30 days to 60 days, and a sentence allowing early termination has been removed. None of these were mentioned in the message. Thanks to the comparison, the tenant raises the points before signing instead of discovering them later.

Good habits when comparing

• Compare before you sign, not after.
• Ask for a tracked-changes version whenever you can; a diff is a safety net.
• Check numbers and dates first, as they matter most.
• Keep both versions with dates in the file names.
• Get professional advice for important legal documents.

Frequently asked questions

What do the colours mean? Green is added text, red and crossed out is removed text.

What is the difference between line and word mode? Line mode marks whole lines; word mode marks individual words within a line.

Can I compare code? Yes, line-by-line mode works well for code.

Is my text uploaded? No. Nothing is uploaded.

Is it free? Yes.

Can I compare two Word files? Copy the text from each file and paste it in the two boxes, or use Word to Text first.

Does it compare formatting? No. It compares text only.

What if the texts are very long? Compare them in sections for easier reading.

Can I compare more than two texts? Compare them in pairs, one after another.

Does it ignore capital letters? It compares exact text, so differences in case will show.

Next step

Open the Text Diff Checker below and find out exactly what changed.