How to Use the Free Regex Tester

Regular Expressions (Regex) are incredibly powerful patterns used to match character combinations in strings. Our free client-side Regex Tester allows you to build, validate, and debug complex regular expressions instantly without ever sending your sensitive text data to an external server.

Simply enter your pattern between the forward slashes / /, modify the matching flags (like g for global or i for case-insensitive), and paste your target text below. The tool will highlight matches in real-time.

Frequently Asked Questions (FAQ)

Which Regex syntax is supported?

StudioLimb's Regex Tester runs directly in your browser using the JavaScript (ECMAScript) Regex engine. This means it fully supports JS-specific features like lookahead, lookbehind (in modern browsers), and named capture groups.

Is my test data private?

100% Private. If you are testing regex patterns against confidential user data, passwords, or emails, it is crucial that this data is not intercepted. Because our tool is pure Client-Side logic, nothing is ever uploaded to a backend. It functions offline.

What do the flags mean?

Flags change how the regex engine searches. g (global) finds all matches rather than stopping after the first. i (ignoreCase) makes [A-Z] match [a-z]. m (multiline) makes ^ and $ match the start/end of a line, not just the whole string.

Online Regex Tester — Real-Time Pattern Matching

Test and debug regular expressions in real time with match highlighting, group captures, and flag support. Works with JavaScript regex syntax.

help How to Use

Enter your regex pattern in the pattern field
Set flags (g, i, m) as needed
Enter test text in the input area
Matches and groups are highlighted in real time

check_circle Common Patterns

Email: [a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}
URL: https?:\/\/[^\s]+
Phone: [\+]?[(]?[0-9]{3}[)]?[-\s\.]?[0-9]{3}[-\s\.]?[0-9]{4,6}
Hex color: #([A-Fa-f0-9]{6}|[A-Fa-f0-9]{3})

tips_and_updates Tips

Start simple — build patterns incrementally
Use g flag to find all matches, not just the first
Use i flag for case-insensitive matching
Capture groups () extract specific parts of a match

Regex Tester

Test String

Match Results