Free · No sign-up · Runs in browser

Regex Tester

Build and debug JavaScript regular expressions with live highlighting, capture groups, and match counts. All processing runs locally in your browser.

Pattern & Test Text
Matches✓ 3 matches
Alice 2024 moved to Austin. Bob 2023 joined Denver, and Carol 2025 relocated to Portland.
#1"Alice 2024"at 0· groups: "Alice", "2024"
#2"Bob 2023"at 28· groups: "Bob", "2023"
#3"Carol 2025"at 56· groups: "Carol", "2025"

About Regex Tester Tool

This free online regex tester lets you build and debug JavaScript regular expressions with live match highlighting. Enter a pattern, choose your flags (gimsuy), and watch matches update in real time as you type. Positional and named capture groups are listed for every match. Perfect for building validators, scrapers, parsers, and search features.

Supported Flags

g global, i case-insensitive, m multiline,s dotAll, u Unicode, y sticky. The tool enforces the g flag internally to enumerate matches while preserving the semantics of your other flags.

Key Benefits

  • Live highlighting: Matches appear in-text as you edit the pattern or flags
  • Capture groups: Positional and named groups are listed for every match
  • Match positions: Each match shows its start index in the source text
  • Fully private: Patterns and test data stay in your browser
  • Guard rails: Up to 1000 matches displayed to keep the UI responsive

Live matching

Matches update instantly as you edit the pattern, flags, or test text.

Fully private

Patterns and test data stay in your browser — safe for proprietary data.

Group capture

Positional and named groups are shown for every match for easy debugging.