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Regex Tester & Debugger

Developer Utilities

Interactive client-side Regular Expression tester and syntax debugger. Features live match highlighting, capture group inspectors, regex flags, and instant templates for emails, URLs, dates, and IPs.

100% Client-Side
//gi
SYNTAX://gi
Hover groups to highlight in text
Flags:
0 Matches Found
Group Legend:
Full Match ($0)
Group 1 ($1)
Group 2 ($2)
Group 3 ($3)
Group 4 ($4)
Preset Patterns with Capture Groups

Regex Replace / Substitution Sandbox

Zero-Knowledge Privacy Guarantee

This Regex Tester & Debugger executes 100% locally in your browser’s JavaScript memory using client-side Web APIs. No inputs, keys, tokens, files, or outputs are ever uploaded to any server or logged in any database.

Key Features & Capabilities

  • Real-time regex matching with live character highlighting
  • Full flag support: Global (g), Case-Insensitive (i), Multiline (m), DotAll (s), Unicode (u)
  • Detailed match list with index positions and named/numbered capture groups
  • Built-in quick templates: Email, URL, IPv4, Phone, Hex Color, ISO Date
  • 100% private: regex testing executes in browser JavaScript

How to Use This Tool

  1. 1Enter your regular expression pattern and toggle desired flags.
  2. 2Paste your test string into the text area.
  3. 3Inspect highlighted matches and capture group breakdowns.
  4. 4Select a preset template to quickly load common regex patterns.

Frequently Asked Questions (FAQ)

It uses the native JavaScript RegExp engine built into modern browsers with full ECMAScript standard compliance.

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