🔍 Text Diff Comparison Pro

Advanced text comparison tool with multiple view modes, character-level diffing, merge support, and version control features. Perfect for code review, document comparison, and change tracking.

✅ Privacy First

Runs entirely in your browser
No text is uploaded to any server
No registration required
Free to use

Original Text (Text A):

Modified Text (Text B):

Chars A

Chars B

Words A

Words B

Lines A

Lines B

📊 Diff Results:

Enter both texts and click "Compare Texts" to see differences...

Character-Level Changes:

Total Lines

Added Lines

Removed Lines

Changed Lines

Similarity

💡 How to use:

Split View: Side-by-side comparison with line numbers
Unified View: Combined view showing all changes
Character Diff: Detailed character-level changes
Green highlights show added or modified content
Red highlights show removed content
Yellow highlights show partial changes
Gray shows unchanged content

📝 Example:

Original Text (Text A):

The quick brown fox jumps over the lazy dog in the forest

Modified Text (Text B):

The quick brown fox runs over the sleeping dog in the dark forest

📚 Use Cases:

Compare document versions and track changes
Code review and version control comparison
Identify character and line-level differences
Content verification and quality assurance
Detect unauthorized modifications
Documentation and change history tracking
Merge conflict resolution assistance

ℹ️ Note: This tool provides line-by-line, word-by-word, and character-by-character comparison. Similarity percentage shows how much content matches between the two texts.

Lines are compared by position

This is not a Git-style diff that hunts for matching blocks. Line 1 of A is held against line 1 of B, line 2 against line 2, to the end of the longer text. Insert one line at the top and everything below shifts out of step:

A: one    two    three   -
B: zero   one    two     three
   changed changed changed added   -> similarity 75%

The percentage is the honest one: it comes from a longest-common-subsequence count over whole lines, so it still reports three of the four lines as shared even though the coloured output calls them all changed. When the panes drift like that, pad the shorter text with a blank line to bring the blocks back into register.

What the counters and panels mean

Changed is a position where both texts have a line and they differ; it is printed as a red minus and a green plus on the same line number. Added and removed occur only past the end of the shorter text.
Blank lines identical in both texts are omitted from the result.
Split and Unified change the input layout only - Unified hides the second box while you scroll. The diff list itself is the same in both.
Character Diff expands the first differing line pair only, and never resynchronises, so one inserted letter paints the rest of that line as changed.

Similarity is built from a full comparison table, so two 5,000-line texts mean 25 million cells. Expect a pause at that size.

Frequently asked questions

Why is every line after my edit marked as changed?

Because you added or deleted a line, and the comparison is positional. From that point on, line 12 of the original is being held against line 13 of the new version. Match the line counts and the noise disappears.

How is the similarity percentage worked out?

It is the length of the longest common subsequence of lines, divided by the line count of the longer text. Lines match only in full, so changing one word costs the whole line.

Is my text uploaded anywhere?

No. The comparison runs in the page, and the Download button builds the file in the browser from what is already on screen. Nothing is sent to a server, so the tool works with the network off.