Diff Checker
Compare two versions of text, code, or files. Highlight line-by-line and word-level changes, find additions and deletions, and review differences instantly.
Private by design: comparisons run entirely in your browser. Your text and files are not uploaded anywhere.
Original Text
Pasted TextModified Text
Pasted TextComparison settings
Line endings (CRLF, LF) are always normalized before comparing, so they never cause false differences.
Result
Similarity = 2 × unchanged ÷ (units in original + units in modified). Units are lines in line mode and characters in word and character modes.
Plain-text unified diff (for manual copying)
What Is a Diff Checker?
A diff checker compares two versions of text or code and identifies additions, deletions, and unchanged content. It is useful for reviewing edits, comparing configuration files, and finding what changed between drafts.
How to Compare Two Texts
Paste or upload the original text on the left and the modified text on the right. Choose a mode and any ignore options, then press Compare. Review the highlighted changes, step through them with Previous and Next, and export the result if you need it.
Line Diff vs Word Diff
Line mode shows which whole lines were added, removed, or changed, and highlights the changed words inside paired lines. Word-level and character-level modes compare the whole text as a token stream, so small edits inside a sentence stand out.
Compare Files
Supported text-based files such as code, JSON, Markdown, CSV, logs, and configuration files can be loaded with the upload button or by dragging them onto a panel. Binary files are rejected with a message.
Is This Diff Checker Private?
Yes. The comparison is calculated locally in your browser. Your text and files are not sent to a server or to any third-party service.
Can It Compare Large Files?
Each uploaded file is limited to 1 MB. Performance depends on input size, the selected mode, and your device. Character-level comparison is limited to 20,000 characters per side, and very different inputs may be shown as one replacement block.
Frequently Asked Questions
Can I compare two code files?
Yes. Load both files or paste them in. Line mode shows changed lines and highlights the changed words within them. The tool treats code as plain text and does not run or validate it.
Can I ignore spaces and line breaks?
You can ignore capitalization, leading and trailing whitespace, the amount of whitespace inside lines, and blank lines. Line-ending differences (CRLF versus LF) are always normalized. Ignored differences are shown as equal, so they are not reported as changes.
Is the unified diff a standard patch?
The unified diff uses the standard hunk format with @@ headers and three lines of context. It is generated from the actual line comparison and can be read by common patch tools.
Why might two files look identical when they are not?
Options such as ignoring capitalization or whitespace intentionally treat some differences as equal. The result tells you which settings are active, so the match is normalized rather than byte-for-byte.
Can I use it on my phone?
Yes. The editors stack vertically on small screens. Very large comparisons are easier on a desktop browser.