Developer
Regex Tester
Test regular expressions against text with live match highlighting.
Text
Find and Replace (Regex)
Find and replace text in one paste — with literal matching or full JavaScript regex, case-sensitivity and whole-word toggles, multiline / dot-all / Unicode-aware flags, and capture-group references (`$1`, `$&`, `$\``) in the replacement. Watch the live match count update as you type so you know exactly what will change before you copy.
ツール要約
このツールは構造化された入力を受け取り、サーバーへアップロードせずにブラウザで決定的な出力を返します。
- ツール名
- Find and Replace (Regex)
- 入力の目的
- 変換・検証・分析するソースコンテンツを入力してください。
- 出力の目的
- コピー・再利用・デバッグに適した正規化された出力を受け取ります。
- 入力例
- The quick brown fox jumps over the lazy fox. Foxes are fast. Find: fox · Replace: cat · Whole word: on
- 出力例
- The quick brown cat jumps over the lazy cat. Foxes are fast.
Recent inputs0
Your last 5 inputs will appear here.
3 matches
The quick brown cat jumps over the lazy dog. The quick brown cat jumps over the lazy dog. cates are fast.
Replacement syntax cheatsheet
$& — the whole match
$1, $2, ... — capture group N
$` — text before the match
$' — text after the match
$$ — literal dollar sign
\n \t — newline / tab (in replacement)
ツールの紹介
Find and replace text in one paste — with literal matching or full JavaScript regex, case-sensitivity and whole-word toggles, multiline / dot-all / Unicode-aware flags, and capture-group references (`$1`, `$&`, `$\``) in the replacement. Watch the live match count update as you type so you know exactly what will change before you copy.
ツール概要
Most online find-and-replace tools either don't support regex or hide capture groups behind a paywall. This one runs entirely in your browser, supports every flag the underlying JavaScript engine offers, and gracefully reports invalid patterns instead of silently doing nothing. Pair it with the existing Regex Tester for crafting a pattern, then bring it here to apply the replacement at scale.
ユースケース
- Bulk-rename variables or imports across a pasted code block
- Reformat a list of items with a regex template
- Strip URL parameters across many lines at once
- Replace placeholder values in an email template
- Convert date formats with capture groups (e.g., 2024-01-15 → 15/01/2024)
入力／出力の例
Whole-word match leaves 'Foxes' (different word) untouched.
入力の目的
The quick brown fox jumps over the lazy fox. Foxes are fast. Find: fox · Replace: cat · Whole word: on
出力の目的
The quick brown cat jumps over the lazy cat. Foxes are fast.
よくある質問
What regex flavor is this?+
JavaScript regex. Everything supported by V8 / SpiderMonkey works — lookbehind, named groups, Unicode property escapes, etc.
Can I reference capture groups in the replacement?+
Yes. $1 through $9 are capture groups, $& is the whole match, $` is text before, $' is text after, and $$ is a literal dollar sign.
Why is 'Whole word' disabled in regex mode?+
In regex mode you can add `\b...\b` yourself for precise control. The whole-word checkbox is a convenience for literal mode.
Will it stop on infinite-loop regex patterns?+
Yes — the engine guards against zero-width matches so a pattern that matches the empty string doesn't lock the page.
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