How to use it
Type a pattern, tick the flags you need and paste text below it. Matches light up as you type, and the table lists each match with its capture groups. The explainer breaks the pattern into pieces, so you can see why it matches. Tick Replace with to preview a substitution using $1, $<name> or $&.
The share link carries only the pattern and flags, never your test text. A pattern that backtracks badly is stopped after two seconds instead of freezing the tab.
Which regex flavour is this?
It uses your browser’s own JavaScript engine. That matches what you get in browser tools, Node.js and most web apps. Python, PCRE (PHP, grep -P) and .NET agree on most basics but differ on some syntax. Python writes named groups as (?P<name>…), and only some engines support possessive quantifiers or atomic groups. Test in the language you will run it in before relying on it.
Regex in OSINT work
Regular expressions pull selectors out of messy text: emails from a leak, IPs from logs, wallet addresses from a forum dump. Our IOC extractor does this automatically for indicators. Use this tester when you need a custom pattern, such as a username format, an order number or a phone style from one country.
Frequently asked questions
Is my text uploaded anywhere?
No. Matching runs in your browser tab, in a separate worker thread. The share link carries only the pattern and flags.
Why does my pattern work here but not in Python?
This page uses the JavaScript regex engine. Python, PCRE and .NET differ on some syntax, such as named groups, lookbehind limits and possessive quantifiers. Test in your target language too.
What does catastrophic backtracking mean?
Some patterns, often nested quantifiers like (a+)+, try an enormous number of paths when a match fails. The tester stops any run after two seconds and tells you, instead of freezing the page.
How do I match across lines?
Tick s so that the dot also matches newlines. Tick m if you want ^ and $ to match at the start and end of every line instead of the whole text.
Can I export the matches?
Yes. Download matches saves every match with its position and capture groups as a CSV file, made in your browser.