Regex Tester — Live Match Highlighting & Pattern Library
Test regular expressions with live match highlighting, flags, and a prebuilt pattern library.
About this tool
Test regular expressions instantly with real-time match highlighting. Toggle flags (g, i, m, s, u), inspect all matches with their positions and capturing groups, and choose from a prebuilt Regex Foundry library of common patterns like email, URL, phone, and password validators.
manage_searchRegex Foundry
Skip writing regex from scratch. The built-in Regex Foundry provides verified, ready-to-use patterns for the most common validation tasks — email, URL, phone number, strong password, and more.
Click any pattern in the Foundry to instantly load it into the tester with a sample test string.
Quick Usage Guide
- 1Real-time regex testing with live match highlighting
- 2Toggle flags: g (global), i (case-insensitive), m (multiline), s (dot-all), u (unicode)
- 3Displays all matches with index positions and capturing groups
- 4Regex Foundry — prebuilt patterns for email, URL, phone, password, and more
- 5Graceful error handling for invalid patterns
- 6100% browser-based — your patterns and data stay private
Frequently Asked Questions
help_outlineWhat regex flags does the tester support?
All standard JS regex flags: g (global), i (case-insensitive), m (multiline), s (dotAll — makes . match newlines), and u (unicode).
verifiedDoes it support capturing groups?
Yes. Each match shows its full matched text plus all capturing groups (group 1, group 2, etc.) individually.
quizWhat is the Regex Foundry?
A built-in library of common, ready-to-use patterns — email, URL, phone, password strength, and more. Click any pattern to instantly load it into the tester with a sample string.
account_balance_walletWhat happens if my regex is invalid?
An error message is shown immediately so you can fix the pattern — the tool never crashes.