Diff Checker

A fast diff checker that compares two texts, highlights changes, and exports patch outputs for developers, writers, and QA teams.

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1,120+

Total Calculations Run

< 15ms

Browser Execution Speed

100%

Client-Side Privacy

4.9 / 5.0

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About This Tool

Diff Checker compares two text passages to identify additions, deletions and substitutions, producing a diff report and an optional patch. It targets developers, writers, QA engineers and editors who review versioned content or code comments.
The tool uses a diff engine to align content at the chosen granularity character, word or line. Options to ignore whitespace and to treat case as sensitive or not refine the matching. Outputs include a unified diff string, a similarity percentage and a patch payload for applying changes.
Unique value lies in precise granularity control, robust handling of large texts, and exchangeable outputs compatible with standard patch tools. Typical use cases include code review, document revision checks, and content auditing across teams.

Save your calculation history with a free account

How to Use

Provide Text A and Text B as inputs.
Select diff mode as character, word or line, and set optional flags for ignore_whitespace and case_sensitive.
Run calculation to generate the diff report, similarity score and patch.
Review the diff_output to see additions, deletions and changes.
Copy or export the patch for applying changes in your workflow.

Frequently Asked Questions

Find Quick Answers

What formats can be exported?

The tool exports a standard unified diff as text suitable for patch applications and can provide a patch payload. For machine consumption, a JSON diff payload can be produced on request. Outputs are designed to integrate with common version control workflows.

How is similarity computed?

Similarity is calculated from the edit script produced by the diff engine. Specifically, similarity equals 100 times one minus the number of edits divided by the maximum length of the two texts. Edits include insertions, deletions and substitutions.

Can this handle large texts?

Yes, within memory and time constraints. For very large inputs, consider chunking the texts or streaming usage. The engine processes a single text pair at a time and reports results when the diff is complete.

Need to run multiple calculations?

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