Regex Tester

Free Regex Tester

This free online regex tester lets you build and check regular expressions in real time. Type a pattern, pick your flags, paste any test string, and every match is highlighted instantly — with a live match count, the captured groups, and the index of each result. It’s free, needs no sign-up, and runs entirely in your browser, so your patterns and text never leave your device.

How to use the regex tester

1. Enter your pattern in the expression box (for example \d+). Don’t add the surrounding slashes — they’re shown for you.
2. Tick the flags you need: g for all matches, i to ignore case, and so on.
3. Paste your test string into the test box on the left.
4. Watch the matches highlight on the right, and read each match’s capture groups in the details list below.
5. Click Copy matches to grab every matched substring at once.

Regex quick reference

A regular expression describes a search pattern. These are the tokens you’ll reach for most often:

• \d — any digit (0–9); \w — a word character (letters, digits, underscore); \s — any whitespace.
• . — any character (except newline, unless the s flag is on).
• + — one or more; * — zero or more; ? — zero or one (optional).
• ^ — start of the string (or line with m); $ — end of the string or line.
• [abc] — a character set matching any one listed character; [a-z] matches a range.
• (...) — a capture group, so you can extract part of the match separately.

The flags change how the whole pattern behaves: g (global) finds every match instead of just the first, i makes matching case-insensitive, m (multiline) makes ^ and $ match at line breaks, s (dotall) lets . match newlines, u enables full Unicode handling, and y (sticky) anchors each search to the previous match’s end.

Frequently asked questions