Free Regex Tester

Test a JavaScript pattern against real sample text — matches, capture groups and a replace preview, with no upload. Paste production log lines safely: everything runs locally.

Privacy Level 1 — 100% local: your files never leave your browser

Free plan: unlimited patterns and test text, no signup. Regex testing often happens on real data — actual customer emails, actual log lines — so this tester runs entirely in your browser: your pattern and test string never leave the device.

Regular expression (without / / delimiters)

Or start from a common pattern

Flags

g — global: find every match

i — case-insensitive

m — multiline

s — dotAll (. matches newlines)

u — unicode

y — sticky

Test text

Replacement preview (optional, $1, $2, $& supported)

Something not working?

Tell us what went wrong — it helps us fix the tool. Only what you type below is sent.

Need more power? Meet Regex Tester Pro

One-time payment. Yours forever. No subscription.

$29

single payment · lifetime updates included

Feature	Free	Pro
Live matches with indices and capture groups	Yes	Yes
Replace preview with $1, $2 and $&	Yes	Yes
Common-pattern presets (email, URL, date, slug)	Yes	Yes
Saved pattern library and test cases	—	Yes
Ads	—	Yes

Get Pro — $29 one-time

Frequently asked questions

Is my test text uploaded?

No. Matching uses your browser's built-in RegExp engine. The pattern and test string never leave your device — that is the whole point, since regex testing is usually done on real log lines and customer data.

Which regex flavour is this?

JavaScript, the same engine Node.js and every browser use. Most Python, PCRE and Java patterns work unchanged, but JavaScript has no possessive quantifiers or atomic groups.

Why does my pattern only find one match?

Without the g flag, a regex stops at the first match — that is also how String.replace behaves. Tick g to find every match.

What do $1 and $& mean in the replacement?

$1, $2 and so on insert capture groups, $& inserts the whole match, and $$ inserts a literal dollar sign — exactly the syntax JavaScript's replace method accepts.