Free Online Diff Checker

A diff checker compares two pieces of text and highlights the differences between them. Lines that were added appear in green, lines that were removed appear in red, and unchanged lines are shown without highlighting. It is commonly used to review code changes, compare document versions, or verify edits.

Unified diff shows all changes in a single column with + and - prefixes for added and removed lines. Side-by-side diff shows the original text on the left and the modified text on the right, making it easier to see corresponding lines.

When enabled, the diff checker treats lines as identical even if they differ only in spaces, tabs, or trailing whitespace. This is useful when comparing code that may have been reformatted but is functionally the same.

Yes. This diff checker works with any text including source code in any programming language. Paste your original and modified code to see exactly what changed, line by line.

When ignore case is enabled, the comparison treats uppercase and lowercase letters as identical. For example, 'Hello' and 'hello' would not be marked as different. This is useful for case-insensitive text comparisons.

Yes. All comparisons happen entirely in your browser using JavaScript. No text is uploaded to any server. Your data never leaves your device, making it safe for comparing sensitive documents or proprietary code.

Green highlighting indicates lines that were added in the modified text. Red highlighting indicates lines that were removed from the original. Lines without highlighting are unchanged between the two versions.

Yes. The diff checker handles large texts efficiently since all processing happens in your browser. For very large files (thousands of lines), the side-by-side view may be easier to navigate than the unified view.