Diff Checker
Compare two blocks of text and see line-by-line differences highlighted.
What Is This Tool?
Compare two blocks of text and instantly see what was added, removed, or left unchanged, highlighted line by line. Everything runs locally in your browser, nothing is uploaded anywhere.
How to Use
- Paste the original text into the left textarea.
- Paste the changed text into the right textarea.
- The highlighted diff appears automatically below as you type.
Common Use Cases
- Comparing two drafts of an article or document
- Spotting changes between two versions of a config file or code snippet
- Reviewing edits before merging or publishing content
Tips & Tricks
- Green highlights are additions, red highlights (struck through) are removals.
- Works with any plain text, not just code.
Frequently Asked Questions
What do the different highlight colors mean in the diff output?
Green highlights mark text that was added in the second version, while red highlights with strikethrough mark text that was removed from the original — unchanged text has no highlight.
Does the diff compare line by line or character by character?
It compares line by line for overall structure while highlighting the specific changed portions within each line, giving you both a high-level and detailed view of what changed.
Can I use this to compare code, not just prose?
Yes. It works with any plain text, including source code, configuration files, or log output — anywhere you need to spot changes between two versions.
Does whitespace-only changes show up in the diff?
Whitespace differences, like extra spaces or different indentation, are typically detected as changes since the comparison is exact — keep this in mind when comparing reformatted code.
Is my text uploaded to a server for comparison?
No. The diff is computed entirely in your browser — neither version of your text is ever transmitted anywhere, so it's safe to compare confidential documents.
Compare two blocks of text and instantly see line-by-line differences highlighted. Free, fast, and processed entirely in your browser.