Regex Tester

Test regular expressions against strings.

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Features

Real-time Matching

Instantly see regex matches highlighted in your text as you type.

Full Flag Support

Toggle Global (g), Case Insensitive (i), Multiline (m), and other regex flags.

Search & Replace

Test substitution patterns with a built-in replace tool.

About Regex Tester

This Regex Tester is a powerful online utility for developers to build, test, and debug JavaScript Regular Expressions. It provides real-time feedback with syntax highlighting, letting you visualize exactly what your pattern matches. Whether you are validating emails, extracting data, or performing complex text substitutions, this tool simplifies the process. It supports all standard JavaScript regex flags and includes a replacement feature to test string transformation logic without writing a single line of code.

How to Use Regex Tester

  • 1
    Enter Regex Pattern

    Type your regular expression in the input field. Do not include the forward slashes /.../.

  • 2
    Set Flags

    Enable flags like 'g' for multiple matches or 'i' for case-insensitive matching.

  • 3
    Add Test String

    Paste the text you want to analyze into the Test String area.

  • 4
    Test Replacement

    Use the Replace section to test substitution strings and view the final output.

Regex Tester - Online Regular Expression Debugger & Tester