Diff Checker
Compare two blocks of text and see the differences highlighted. Perfect for code reviews, document comparison, and more.
Differences
What Is a Diff Checker?
A diff checker (also called a text comparison tool) lets you compare two pieces of text and instantly see what has changed between them. It highlights additions, deletions, and modifications line by line, making it easy to spot differences in code, documents, configurations, or any text content.
Common Use Cases
- Code reviews — Compare two versions of source code to see what changed
- Document comparison — Find differences between contract drafts or articles
- Configuration files — Spot changes in server configs, .env files, or JSON settings
- Debugging — Compare expected vs. actual output to find bugs
- Content editing — Track changes between document revisions
How It Works
Our diff checker uses the Longest Common Subsequence (LCS) algorithm to find the optimal alignment between the two texts. Lines that exist only in the original are marked as removed, lines only in the modified version are marked as added, and matching lines are shown as unchanged. Everything runs in your browser — no data is sent to any server.
Frequently Asked Questions
Is my data safe?
Yes. The comparison runs entirely in your browser using JavaScript. No text is uploaded to any server.
Can I compare code files?
Absolutely. The diff checker works with any plain text — source code, JSON, XML, Markdown, configuration files, or prose.
What does "ignore whitespace" do?
When enabled, the tool trims leading and trailing spaces from each line before comparing, so differences caused only by indentation changes are ignored.