Text Diff Checker
Paste two versions of a document into the boxes below and click Compare to see exactly what changed. Added lines are highlighted in green, removed lines in red, and unchanged lines are shown in grey. The tool runs entirely in your browser — nothing is uploaded.
How to Use the Text Diff Checker
Paste your original text in the left box and your modified version in the right box. Click Compare. The tool performs a line-by-line diff and shows both versions side by side with colour highlighting:
- Green lines — appear only in Version B (added).
- Red lines — appear only in Version A (removed).
- Grey lines — identical in both versions (unchanged).
Common Use Cases for a Diff Checker
- Document revision tracking — compare two drafts of an essay or report.
- Code review — spot differences between two versions of a config file or script.
- SEO content audits — compare updated web copy against the previous version.
- Contract or legal text — identify clause changes between versions.
- Data validation — check if two data exports match line for line.
Line-by-Line vs Word-by-Word Diff
This tool performs a line-by-line diff, which is the standard approach for code and structured text. For prose where sentences flow across lines, consider breaking your text into sentences first, one per line, using the Remove Line Breaks tool or a text editor.
Frequently Asked Questions
What does a diff checker show?
It compares two versions of text line by line, highlighting lines that were added (green), removed (red), or unchanged (grey).
Can I compare code with this tool?
Yes. It works on any plain text including source code, JSON, HTML, CSS, Markdown or prose — comparing line by line regardless of content type.
Is the comparison case-sensitive?
Yes by default. Enable "Ignore case" to treat lines with different capitalisation as identical.
How many lines can I compare?
The tool handles large documents in your browser. Performance is good up to several thousand lines.