Guides JP

Text Diff Checker

Compare two texts side by side and highlight all differences with color coding. Advanced options to ignore whitespace, case, and more. All processing is done in your browser — no data is sent to our servers.

Last updated: 2026/10/16 Text Feedback & bug reports
Comparison Options
Original Text
Modified Text

How to Use

1

Enter Texts

Enter the original text on the left and the modified text on the right. You can also drag & drop files.

2

Set Options

Set comparison options (ignore case, whitespace, etc.) as needed.

3

Compare

Click the "Compare Texts" button to highlight all differences.

4

Review Results

Use the navigation buttons to jump between changes. Switch between side-by-side and inline views.

About This Tool

A powerful text diff checker that compares two texts and highlights all differences. On top of line-by-line diffing, it highlights changes within modified lines at the character or word level, and offers options to ignore whitespace, ignore case, and normalize full-width/half-width characters, plus statistics for added and removed lines. With advanced normalization options for Japanese text (full-width/half-width, hiragana/katakana), it's perfect for proofreading and document comparison. All processing happens in your browser — your data never leaves your device.

For bulk find-and-replace, try the Text Replace tool; to sort lines or remove duplicates, use the Text Sort & Dedupe tool; and to compare JSON structures, see the JSON Diff tool.

Key Features

  • Advanced Comparison OptionsIgnore whitespace, case, full-width/half-width differences and more.
  • Side by Side & Inline ViewCompare texts side by side or in a single-column inline view.
  • File Import SupportDrag & drop files directly for instant comparison.
  • Privacy FirstEverything processed in your browser. No data sent to servers.

Use Cases

  • Document revision checking and proofreading
  • Code change review
  • Contract and policy amendment tracking
  • Translation text comparison
  • Website content update management

FAQ

Is my data sent to a server?
No. All processing is done in your browser and text data is never sent to any server. You can safely compare confidential documents.
Can I ignore full-width and half-width differences?
Yes. Enable the "Ignore full-width/half-width" option to treat characters like "ＡＢＣ" and "ABC" as identical.
Can it detect hiragana/katakana differences?
Yes. By default, hiragana and katakana are treated as different characters. Enable the "Ignore hiragana/katakana" option to treat them as the same.
What is the maximum number of lines?
Up to 50,000 lines are supported. Processing may take longer for texts exceeding 10,000 lines.
Can I load files directly?
Yes. Drag & drop files directly onto the text area or use the file selection button. UTF-8, Shift_JIS, and EUC-JP encodings are supported.
Can I compare word by word?
Yes. Turn on the "Word-level" toggle in the result toolbar to highlight changes by word or phrase instead of by character. This makes edits easier to read in English text or program code where word boundaries are clear. Turn it off to return to character-level highlighting.
Can I see how many lines were added or removed?
Yes. The result view shows Added, Removed, Differences, and Change rate statistics at the top, so you can instantly see the number of added, removed, and modified lines along with the overall change rate. The statistics are recalculated automatically when you toggle options such as ignore whitespace, ignore case, or full-width/half-width normalization.

Related Tools

Character Counter Count characters, words, and lines in real-time Fullwidth/Halfwidth Converter Convert between halfwidth and fullwidth characters Text Replace Tool Find and replace text with regex support Mojibake Fixer Auto-detect and fix garbled text encoding あ Furigana Generator Automatically add furigana readings to Japanese kanji

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