What is a Regex Tester?

A Regex Tester is an online tool that allows you to write, test, and debug regular expressions in real-time. It highlights matches, groups, and replacements instantly.

Which regex flavors are supported?

The tool supports JavaScript (ECMAScript) regex, with many patterns also compatible with PCRE, Python, PHP, C#, and Java.

Can I use regex for replacements?

Yes. You can test regex-based replacements and preview transformed text instantly.

Is my input text stored?

No. Everything runs locally in your browser, ensuring your test text and regex patterns remain private.

Toolzium

Regex Tester

Test & debug regular expressions online.

Pattern & Flags

Write your regex, toggle flags, tweak limits.

Pattern

Flags

g=global, i=ignore case, m=multiline, s=dotAll, u=unicode, y=sticky

Presets

Match limit

Timeout (ms)

Auto-run

Re-run on every change

/\b[A-Za-z]+\b/g

Test Area

Type or paste your text to test the pattern on.

Test Text

Matches (0)

No matches found.

UUID / NanoID Generator

Generate unique UUIDs (v4), NanoIDs, and short IDs online. Create universally unique identifiers for…

Color Converter

Convert between HEX, RGB, HSL, and CMYK color formats. Color picker and converter with live preview.…

Regex Library

Collection of useful regular expression patterns for email, URL, phone, credit card validation, and …

Markdown Previewer

Preview Markdown syntax and convert to HTML in real-time. Markdown editor with GitHub-flavored markd…

Number Base Converter

Convert numbers between binary, octal, decimal, and hexadecimal bases. Base converter with support f…

Hash Generator

Generate MD5, SHA1, SHA256, SHA512, and other cryptographic hashes online. Hash text, files, and pas…