Text Diff Checker
Compare two blocks of text.
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About Text Diff Checker
Text Diff compares two blocks of text line by line and shows you exactly what changed. Paste an original version on the left and a changed version on the right, and it highlights added lines in green with a plus and removed lines in red with a minus, while unchanged lines stay neutral. It also counts how many lines were added, removed, and left untouched.
The tool is completely free with no sign-up, no limits, and no watermarks. It runs entirely in your browser using a built-in LCS diff algorithm, so the text you paste never leaves your device or gets uploaded to any server.
Frequently asked questions
- Is the Text Diff tool free to use?
- Yes, it is 100% free with no account, no sign-up, and no usage limits. You can compare as many texts as you want, as often as you want.
- Is my data uploaded anywhere when I compare text?
- No. The entire diff is computed locally in your browser using JavaScript. Nothing you paste is ever sent to a server, stored, or uploaded, so it is safe for private or sensitive text.
- How does the line-by-line diff work?
- It uses a Longest Common Subsequence (LCS) algorithm to find the lines the two versions share, then marks the rest as added or removed. Added lines appear green with a + prefix and removed lines appear red with a - prefix.
- Can I compare code, documents, or configuration files?
- Yes. Any plain text works, including source code, JSON, CSV, markdown, essays, and config files. The diff is based on lines, so it is well suited to code and structured text.
- What does the 'Ignore leading and trailing whitespace' option do?
- When enabled, lines that differ only by spaces or tabs at the start or end are treated as unchanged. This is handy when indentation or trailing spaces were reformatted but the actual content is the same.
- Does it work in dark mode and on mobile?
- Yes. The added and removed highlights use semi-transparent colors that stay readable in both light and dark themes, and the layout is responsive so it works on phones, tablets, and desktops.