Agent X Alpha

Regex Tester & Builder

Client-SideOffline Ready

Write, test, and explain Regular Expressions in real-time against sample text with visual highlights.

Presets:
//
63 chars
7 Matches
Hello World, this is a Test String with Some Capitalized Words.
Match Details (7)
#1"Hello"Groups: ["H"]
idx: 0 (len: 5)
#2"World"Groups: ["W"]
idx: 6 (len: 5)
#3"Test"Groups: ["T"]
idx: 23 (len: 4)
#4"String"Groups: ["S"]
idx: 28 (len: 6)
#5"Some"Groups: ["S"]
idx: 40 (len: 4)
#6"Capitalized"Groups: ["C"]
idx: 45 (len: 11)
#7"Words"Groups: ["W"]
idx: 57 (len: 5)

Real-time Regex Engine

Test, evaluate, and debug Regular Expressions instantly with visual match highlighting and capture group breakdowns.

Visual Pattern Builder

Construct complex regex patterns visually without memorizing arcane syntax using configurable character rules.

Substitution & Code Generator

Simulate text replacements with capture group backreferences and export code snippets in JS, Python, Go, and PHP.

Frequently Asked Questions

Which regular expression flavor is supported by this tester?
The tester uses standard JavaScript ECMAScript (ES2024) regex engine with full support for global (`g`), case-insensitive (`i`), multiline (`m`), dotAll (`s`), and unicode (`u`) flags.
Can I inspect capture groups and match indices?
Yes. All matches and capture groups are highlighted in real-time with color-coded badges, character offsets, and match counters.
Is my test data uploaded to any server?
No. Pattern compilation and string matching run 100% locally in your browser memory. Your proprietary text, logs, and sensitive regex patterns never leave your machine.
Does the tool provide built-in regex presets for common formats?
Yes. Presets include email validation, URLs, IPv4/IPv6 addresses, ISO dates, hex colors, UUIDs, phone numbers, and slug validation patterns.
Recommended For You

More Dev Tools Utilities

View all Dev Tools tools
Dev Tools

AI Crawler & Robots.txt Simulator

Simulate and test robots.txt compliance against AI scrapers (GPTBot, ClaudeBot, CCBot, Bytespider) and search engines (Googlebot, Bingbot). Audit URL paths and generate AI-safe rules.

Server APILaunch
Dev Tools

Mock JSON / Seed Data Generator

Generate realistic schema-driven mock datasets in JSON, NDJSON, SQL INSERT statements, CSV, and TypeScript interfaces 100% locally in your browser.

Client-SideLaunch
Dev Tools

SVG to React / TypeScript Component Converter

Transform raw SVG markup into production-ready React (JSX/TSX) components with custom props, forwardRef, size controls, and currentColor inheritance.

Client-SideLaunch