DIFF (Text Diff Comparison)
Compare text and show the differences
Features
Color-codes the changes
Deletions in red, additions in green, so differences are clear at a glance
Precise character-level highlighting
Colors only the characters that changed within a line to make differences explicit
Side-by-side before-and-after comparison
Displays before and after side by side with line numbers
Try it instantly with a sample
Load the provided example text and check how it works right away
How to use
Enter the two texts to compare
Paste the before text on the left and the after text on the right (up to 10,000 characters each)
Compare with the run button
Press the run button to compute the differences and display the results table
Review the diff results
Scroll through the results table to inspect the changed lines and differing characters in order

Use cases
Proofreading and revising documents
Compare drafts before and after editing to catch every addition and deletion
Reviewing source code changes
Line up code before and after editing to quickly grasp the scope of changes
Checking revisions to contracts and terms
Compare old and new clauses to inspect changed wording without missing anything
Cross-checking translations and rewrites
Contrast the original with the rewritten version to confirm the intended changes were applied
Basic Knowledge
What is diff (difference)?
Diff is the process of comparing two texts to identify added, deleted, or changed parts, as well as the result of that comparison. It is widely used from verifying program changes to reviewing document revisions.
Why differences appear even when things look the same
Diff comparison is performed on a character-by-character basis, so differences that are hard to notice visually are detected. Differences between half-width and full-width spaces, the presence or absence of line breaks, and differences between full-width and half-width alphanumeric characters appear as separate characters in diffs even though they look nearly identical on screen.
Safety and privacy
Runs entirely in your browser
Your input data is processed only within your browser and is never sent externally.
Processing only in your browser
comparing the differences is processed entirely within your browser, and input data is not sent to any server.
Communications encrypted with HTTPS
Page loading is also encrypted by TLS, and content cannot be read by third parties.
No transmission to third parties
Input content is not sent to external services such as ad networks or trackers.
No automatic saving of results
the compared text and input suggestions are not stored on the server.
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Updates
- update #98
Improved readability of DIFF (text comparison) line number backgrounds and difference colors
Featured Tools
RAKKOTOOLS is free to use!
Available free of charge for individuals and corporations, commercial and non-commercial use alike.No prior permission or usage application is required. Feel free to use it in various situations.

Use in streaming and videos
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Use in schools, work, and events
Can be used in various situations such as classes, team division, internal work, and events.

Introduction on Web, books, and SNS
Feel free to introduce it as a useful tool on web media, books, SNS, and other platforms.

Commercial use
Can be used for commercial purposes such as research, calculation, processing, and conversion in business and production.
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If using in streaming and videos
Link to RAKKOTOOLS in the description, or Mention or display that you are using RAKKOTOOLS in the stream or video.
Credit example for the description
Usage guidelinesYou are free to use it for normal purposes. However, use for purposes that violate laws, infringe on third-party rights, impose significant load on the service, or otherwise interfere with service operation is prohibited.
We do not guarantee the accuracy or completeness of information and calculation results obtained from each tool.
This notice is a translation of the original Japanese text. If there is any discrepancy between the translation and the original, the Japanese original takes precedence.
