How do I validate an email in PHP?

Use `filter_var($email, FILTER_VALIDATE_EMAIL)` instead of regex for best results. If you must use regex, `^[\w-\.]+@([\w-]+\.)+[\w-]{2,4}$` covers most cases.

What does the 'm' flag do in PCRE?

The 'm' (multiline) flag changes the behavior of `^` and `$` assertions. With it, they match the start and end of each line, not just the start and end of the string.

How to match a specific number of digits in PHP regex?

Use the quantifier `{n}`. For example, `\d{4}` matches exactly 4 digits. To match between n and m digits, use `{n,m}`, like `\d{2,4}`.

How does the Visual Regex Builder work?

Our Visual IDE allows you to build patterns using drag-and-drop blocks. It visualizes the logic of your regex, making it easier to understand matching behavior and debug errors without memorizing syntax.

Is my data safe when using this regex tester?

Yes. TestRegex.com operates with a **Local-First** architecture. Your regex patterns and test strings are processed entirely within your browser using WebAssembly. No data is sent to our servers.

Can AI help me fix my regex?

Yes. Our 'AI Refactor' tool analyzes your pattern and suggests optimizations for performance and readability, helping you avoid common pitfalls like catastrophic backtracking.

TestRegex

Blog Patterns About Quiz

Runtime: PCRE2 (Wasm)

Regular Expression Ctrl + /

- - 0.00 ms

Test String Ctrl + .

Match Information

Detailed match information will be displayed here automatically.

Lookup

Full Cheatsheet →

Match Information

Detailed match information will be displayed here automatically.

Lookup

Full Cheatsheet →

Regular Expression Ctrl + /

Test String Ctrl + .

Frequently Asked Questions

PCRE / PHP Regex Tester & Visual IDE

PCRE (Perl Compatible Regular Expressions) Visual IDE

Supported Flags & Features