Regex Tester
FreeBuild, test, and debug regular expressions with real-time highlighting of matches. See capture groups, match positions, and detailed explanations of your regex pattern. Supports JavaScript, Python, and PHP regex flavors. Includes a quick-reference cheat sheet and common regex pattern library to speed up your development workflow.
How It Works
Upload or enter your data
Drag and drop your file or paste your content into the tool input area.
Configure options
Adjust settings and preferences to get exactly the output you need.
Get your result
Download your processed file or copy the output. Everything happens in your browser.
Frequently Asked Questions
Our tester supports JavaScript (default), Python, and PHP regex flavors. Each flavor has slightly different syntax rules and features, which are clearly documented in the reference panel.
Yes, capture groups are highlighted with distinct colors. The match details panel shows each group's value, start/end position, and named group labels if applicable.
Yes, a built-in cheat sheet covers common patterns, character classes, quantifiers, anchors, lookaheads, and more. You can also browse a library of common regex patterns for emails, URLs, dates, etc.
Related Tools in Developer Tools
JSON Formatter & Validator
Format, validate, and beautify JSON data instantly
Base64 Encode/Decode
Encode and decode Base64 strings and files
URL Encode/Decode
Encode and decode URL components and query strings
HTML/CSS/JS Minifier
Minify HTML, CSS, and JavaScript to reduce file sizes
Color Picker & Converter
Pick colors and convert between HEX, RGB, HSL, and more
JWT Decoder
Decode and inspect JSON Web Tokens instantly
Markdown to HTML
Convert Markdown to clean, semantic HTML
Code Beautifier
Format and beautify code in 20+ programming languages