Regex Tester
Test regular expressions in real time.
Your pattern and text are processed entirely in your browser — never uploaded or stored.
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What is this tool?
The regex tester applies a regular expression pattern and flags to your test string instantly, highlighting matches and listing group captures in a table — handy for writing and debugging validation patterns or parsing rules.
Flags
- g: global — find all matches, not just the first.
- i: case-insensitive matching.
- m: ^ and $ also match the start/end of each line.
- s: . (dot) also matches newline characters.
- u: treat the pattern as Unicode code points.
- y: sticky — only match starting at lastIndex.
Note: without the g flag, only the first match is shown.
Privacy & processing
Everything runs in your browser. Your pattern and text are never uploaded or stored.
FAQ
What is a regular expression?
A regular expression is a notation for finding or validating patterns in strings — used for email/phone format checks, text replacement, log parsing, and more, supported by nearly every programming language including JavaScript.
What do flags like g, i, m mean?
Flags change matching behavior. g (global) finds all matches instead of just the first; i (ignoreCase) ignores case; m (multiline) makes ^ and $ match each line's start/end; s (dotAll) makes . match newlines too; u (unicode) processes by Unicode code point.
How do I check group captures?
Wrapping part of a pattern in parentheses ( ) creates a group; each match then captures that group's substring separately. This tool lists the full match and each group's captured value in the match table.
Can I see multiple matches without the g flag?
No. Without the g flag, a regex stops after the first match. To find every match in the string you must enable the g flag.
Is my pattern and text sent to a server?
No. All matching happens in your browser; your pattern and text are never uploaded or stored.
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