Diff Checker — 2つのテキストをオンラインで比較

2つのテキストを並べて比較し、差分を即座に検出。行・単語・文字単位のdiff、分割/統一表示対応。完全ブラウザ処理、無料。

粒度

表示

オプション大文字小文字を無視空白を無視JSONモード（自動整形）未変更を折りたたむ

元のテキスト

変更後のテキスト

2つのテキストを貼り付けて「比較」をクリックすると差分が表示されます。

機能

100% Browser-Based

All comparison runs locally in your browser. Your text never leaves your device.

Free & No Sign Up

No registration, no limits, no hidden fees. Just paste and compare.

Instant Results

See differences highlighted in real time as soon as you click Compare.

Line / Word / Character Diff

Switch between line, word and character-level granularity to find the exact change.

Split & Unified Views

Side-by-side for wide screens, Git-style unified diff for narrow screens or sharing.

JSON-Aware Mode

Auto-format both sides as JSON before diffing — no more noise from minified payloads.

How to use the Diff Checker

Paste your original text into the left panel.
Paste the modified text into the right panel.
Choose granularity: Lines, Words, or Chars (and toggle JSON mode if comparing JSON).
Click Compare — additions and deletions are highlighted instantly.
Switch between Split and Unified view, or use Swap / Copy / Clear as needed.

Common Use Cases

Code Review

Quickly review changes before committing — see exactly which identifiers, literals or operators were touched.

Config Drift

Compare environment configs (JSON / YAML / .env) between staging and production to spot drift.

Document Editing

Compare two versions of a contract, blog draft or email to see exactly what was rewritten.

Log Investigation

Diff two log snapshots to isolate what changed between a working run and a broken one.

API Regression

Compare two JSON API responses to confirm whether a code change broke the expected payload.

Merge Conflict Help

Paste two branches of a conflicted file to visualise differences before resolving by hand.

Pro Tips

✓ Use Lines for code, Words for prose, Chars for hunting single-character typos.
✓ Turn on "Ignore whitespace" when comparing code that may have been re-indented.
✓ Turn on "Ignore case" for case-insensitive prose comparison.
✓ Switch to Unified view before pasting a diff into an issue or email — it travels better than a screenshot.
✓ Enable JSON mode to compare minified vs. pretty payloads without noise.
✓ Use Swap to flip the two sides if you accidentally pasted them in the wrong order.

よくある質問

How do I compare two texts online?

Paste your original text into the left panel, the modified text into the right panel, then click Compare. The tool highlights additions in green, deletions in red, and unchanged lines in neutral.

What is the difference between split and unified view?

Split view shows the original and modified versions side by side in two columns — best for wide screens and long files. Unified view interleaves both versions in a single column with + and − markers, similar to git diff output — best for narrow screens or pasting into a ticket.

When should I use line, word, or character diff?

Use line diff for code and structured text, word diff for prose and documents, and character diff for precise editing or single-character typos. Most code reviews start with line diff and zoom into word/character only when needed.

Can I compare JSON or minified code?

Yes. Toggle the JSON mode and the tool will pretty-print both sides as JSON before diffing, so structural changes show up cleanly without noise from one-liner formatting.

Is my data sent to any server?

No. The entire comparison runs inside your browser using a local diff library. Nothing is uploaded, stored, or transmitted — your text is yours alone.

How big a text can I compare?

There is no fixed cap, but very long inputs (tens of thousands of lines) may slow your browser. For best performance keep each side under ~10,000 lines.