RegExp Tester
Test regular expressions with live matches.
Runs in your browser: what you paste is never uploaded
Flags
How to use RegExp Tester
- 1Paste or type your inputUse the box above, or click Sample to try it with an example.
- 2Choose your optionsEnter the pattern and flags (g, i, m, s, u, y), then the test text; add a replacement to preview substitutions.
- 3Copy the resultCopy it with one click. Nothing is sent anywhere.
About RegExp Tester
Test JavaScript regular expressions against your text with live highlighting, capture groups and a replace preview.
Frequently asked questions
Which regex flavour is this?
JavaScript (ECMAScript), as used in browsers and Node.js. Other flavours like PCRE differ in some features.
What happens with a pattern that never finishes?
Runaway patterns (catastrophic backtracking) are stopped after a second instead of freezing the page.
Is what I paste sent anywhere?
No. The tool runs entirely in your browser and never sends what you type or paste to a server.
Is it free?
Yes. It's free, with no sign-up and no limits.
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