テキスト比較

The Text Diff tool compares two blocks of text side by side and highlights which lines were added, removed, or unchanged. It uses a line-based LCS (Longest Common Subsequence) algorithm, similar to the Unix diff utility.

Paste your original text in the left panel and the modified text in the right panel. The diff output updates automatically below, with green highlighting for added lines, red for removed lines, and neutral styling for unchanged lines.

A + prefix (green) marks lines present only in the modified text. A - prefix (red) marks lines present only in the original. A space prefix (neutral) marks lines identical in both versions. This follows the standard unified diff format.

Yes — above the diff output, the tool shows a count of added lines, removed lines, and unchanged lines so you can quickly assess the scope of changes without reading through every line.

Yes — the tool is fully Unicode-aware and works with any language or script, including CJK characters, Arabic, Hebrew, and emoji. Line comparison is done on the raw text content regardless of script.

Yes — the default comparison is case-sensitive, so 'Hello' and 'hello' are treated as different lines. This mirrors standard diff tools and is the most predictable behavior for code and structured text.

Yes — the monospace font and line-by-line output make it well-suited for comparing code snippets, configuration files, and any structured text. For full version-control diffing, a dedicated tool like git diff provides more features.

The tool runs the LCS algorithm entirely in the browser with no file size limit enforced. Performance depends on the size of the input and your device; very large files (thousands of lines) may cause a brief delay.

Unicode text can contain look-alike characters, invisible characters, or mixed encodings that are visually identical but technically different. Text Diff will show these as changed lines, helping you spot encoding inconsistencies that a visual read-through would miss.

No — all comparison processing runs locally in your browser using JavaScript. Your text is never sent to any server, making the tool safe for diffing sensitive or confidential content.