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.
Tool Summary Answer Block
This tool accepts structured input and returns deterministic output in the browser with no server upload.
- Tool name
- Find and Replace (Regex)
- Input intent
- Provide source content to transform, validate, or analyze.
- Output intent
- Receive normalized output suitable for copy, reuse, or debugging.
- Example input
- The quick brown fox jumps over the lazy fox. Foxes are fast. Find: fox · Replace: cat · Whole word: on
- Example output
- 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
$$ — literal dollar sign
\n \t — newline / tab (in replacement)
Tool Introduction
Find and replace text in one paste — with literal matching or full JavaScript regex, case-sensitivity and whole-word toggles, multiline / dot-all / Unicode-aware flags, and capture-group references (`$1`, `$&`, `$\``) in the replacement. Watch the live match count update as you type so you know exactly what will change before you copy.
Tool Overview
Most online find-and-replace tools either don't support regex or hide capture groups behind a paywall. This one runs entirely in your browser, supports every flag the underlying JavaScript engine offers, and gracefully reports invalid patterns instead of silently doing nothing. Pair it with the existing Regex Tester for crafting a pattern, then bring it here to apply the replacement at scale.
Use Cases
- Bulk-rename variables or imports across a pasted code block
- Reformat a list of items with a regex template
- Strip URL parameters across many lines at once
- Replace placeholder values in an email template
- Convert date formats with capture groups (e.g., 2024-01-15 → 15/01/2024)
Input/Output Examples
Whole-word match leaves 'Foxes' (different word) untouched.
Input Intent
The quick brown fox jumps over the lazy fox. Foxes are fast. Find: fox · Replace: cat · Whole word: on
Output Intent
The quick brown cat jumps over the lazy cat. Foxes are fast.
FAQ
What regex flavor is this?+
JavaScript regex. Everything supported by V8 / SpiderMonkey works — lookbehind, named groups, Unicode property escapes, etc.
Can I reference capture groups in the replacement?+
Yes. $1 through $9 are capture groups, $& is the whole match, $` is text before, $' is text after, and $$ 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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