Text Diff Checker
Compare two texts line by line and see exactly what was added, removed, or left unchanged, with counts for each.
Text Diff Checker Online Free
Comparing two versions of a document by eye is slow work, and it is easy to miss the one line that changed. A contract, an essay or a page of code can look identical at a glance while a date, a price or a whole sentence has quietly moved. A diff checker does the close reading for you, comparing both texts line by line and marking every line that was added, removed or left unchanged. This free tool shows added lines in green, removed lines in red, and gives you the counts for each, all inside your browser. Paste the original, paste the new version, click Compare, and see exactly what changed in seconds.
What Is a Diff Checker?
A diff checker is a tool that compares two pieces of text and reports the differences between them. This checker works line by line, so every line of the first text is matched against the lines of the second text. Lines that appear in both are left unchanged, lines found only in the new text are marked as added, and lines found only in the original are marked as removed.
The result is shown in a panel labelled Diff result. Added lines appear on a green background with a plus sign, removed lines appear on a red background with a minus sign, and unchanged lines are shown plainly. Above the result, badges show how many lines were added and how many were removed, so you can judge the size of the change before reading it in detail.
Unlike comparison features buried inside paid office software, this tool runs in your browser the moment the page loads. Your texts are compared on your own device and are never uploaded, which makes the tool safe for contracts, drafts and other private documents. It accepts up to 2000 lines on each side, which covers most documents people compare day to day.
How to Compare Two Texts Online
Open the Text Diff Checker
Open the tool page in your browser on any device. You will see two text boxes side by side on wide screens, labelled Original and Modified, with a Compare button below them and no account or payment needed to begin.
Paste the original text
Click inside the box labelled Original and paste the version of your text that you want to compare against. Its placeholder reads Paste the original text here. Keep the line breaks as they are, because the comparison follows them.
Paste the modified text
Click inside the box labelled Modified and paste the version of your text you want to check. Its placeholder reads Paste the modified text here. Order matters, because it decides which lines count as added and which count as removed.
Click the Compare button
Click the Compare button below the two boxes. The tool splits both texts into lines and works through them, matching lines that stayed the same and marking the rest as added or removed, then builds your result panel.
Read the Diff result panel
Read the Diff result panel that appears below. Added lines sit on a green background with a plus sign, removed lines sit on a red background with a minus sign, and unchanged lines are shown in a muted style.
Check the added and removed counts
Look at the two badges above the result, which show how many lines were added and how many were removed. If either text passed 2000 lines, a note explains that the comparison was capped at 2000 lines per side.
Copy the result and act on it
Use the copy option on the Diff result panel to save a plain text version of the comparison, with a plus or minus sign on every changed line. Then fix your document, or paste revised texts and compare once more.
Key Features
Completely free with no limits on typical use
Compare as many documents as you need without a paywall, a daily quota or a trial that expires halfway through your work.
No signup or account required
Open the page and start comparing at once. There is no email form, no password and no profile to manage first.
Private by design
Both texts are compared locally in your browser and are never uploaded to a server, so contracts and private drafts stay on your device.
Line by line comparison
Every line is matched against the other text, so changes are reported at the exact line where they happened rather than as a rough summary.
Colour coded results
Added lines glow green with a plus sign and removed lines glow red with a minus sign, while unchanged lines stay muted and easy to skip.
Added and removed counts
Badges above the result state how many lines were added and how many were removed, giving you the size of the change at a glance.
Copyable plain text result
The copy option saves the whole comparison as plain text with plus and minus marks, ready to paste into an email, a ticket or your notes.
Who Needs This Tool?
Writers and editors
Drafts change many times before they are finished, and authors forget what moved. Comparing the last two drafts shows every edited line, so nothing is lost or repeated by accident.
Software developers
Code reviews and file updates often come down to a handful of changed lines in a long file. A quick comparison shows exactly which lines changed before the update goes live.
Students and teachers
Students can compare an essay draft with the improved version to see their own progress, and teachers can check what a student actually changed between two submissions of the same work.
Office and legal teams
Contracts, policies and letters go through rounds of edits between teams. Comparing versions line by line proves which wording changed, which protects everyone when the final version is signed.
Proofreaders
A proofreader needs to confirm that only the agreed corrections were made and nothing else shifted. The colour coded result turns that check into a quick scan instead of a full reread.
Website owners
Page copy, product details and help articles are updated again and again. Comparing the old and new text before publishing confirms the update says exactly what it was meant to say.
Tips for Best Results
Keep the line structure the same in both texts
The comparison follows line breaks, so one long paragraph counts as a single line. Give both versions the same line breaks, and small edits inside a paragraph become easy to spot.
Put the versions in the right order
Original goes in the first box and the newer version goes in the second. Swapping them turns every added line into a removed line, which makes the result confusing to read.
Split very long documents into parts
Each side is compared up to 2000 lines, and a note appears when a text goes past that. For longer files, compare chapter by chapter so every line gets checked.
Read the counts before the details
The added and removed badges tell you whether you are looking at a light edit or a major rewrite. Knowing that first helps you decide how carefully to read each line.
Save a copy of the result for your records
The copied plain text version keeps the plus and minus marks, so it works as a simple change record. Paste it into the project notes before you close the page.
Watch for blank line changes
An empty line added or removed still counts as a changed line, and spacing edits can fill the result. If counts look high, check whether blank lines explain the difference.
Frequently Asked Questions
Is the diff checker free to use?
Yes. The tool is completely free, with no account, no subscription and no hidden charges. You can compare as many pairs of texts as you need, and the Compare button, the colour coded result and the copy option all work for every visitor. There is no paid tier waiting behind the result, and nothing about the comparison is limited by a daily quota.
Are my texts uploaded to a server?
No. The comparison runs entirely in your web browser on your own device, and both texts stay there from start to finish. That is why the tool is safe for private material such as contracts, letters, drafts and settings files. Nothing is stored after you close the page, and there is no history of your comparisons kept anywhere for anyone to see.
How does the checker decide what was added or removed?
The tool splits each text into lines and matches the lines of one text against the lines of the other. A line that appears in both counts as unchanged, a line found only in the Modified text counts as added, and a line found only in the Original text counts as removed. The result then lists every line in order with its mark.
Why does one edited line show as removed and added?
Because the comparison works on whole lines, any change inside a line marks the entire line. The old wording appears once as a removed line in red, and the new wording appears once as an added line in green, even if only one word changed. Reading the red and green pair together shows you exactly what the edit was.
What happens if my text has more than 2000 lines?
The checker compares up to 2000 lines on each side, which covers most documents, essays and files people compare by hand. If either text is longer, only the first 2000 lines of that side are compared, and a note above the result tells you the cap was reached. For very long files, split the text into sections and compare one section at a time.
Can I save or share the comparison result?
Yes. The copy option on the Diff result panel copies the whole comparison as plain text, with a plus sign on added lines, a minus sign on removed lines and plain spacing on unchanged lines. You can paste that text into an email, a document or a project ticket, where it reads clearly even without the green and red colours.
Conclusion
Finding the exact lines that changed between two versions should take seconds, not a careful reread of both documents. Paste the original, paste the modified version, click Compare, and read a colour coded result with clear counts and a copy you can keep. Whether you are polishing an essay, reviewing code or checking a contract, this free checker shows you what changed and lets you move on with confidence.
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