Regex Tester

What Is the Regex Tester?

A regex tester lets you write a regular expression pattern and test it against a string to see all matches, their positions, and capture groups—without writing code.

Writing correct regexes is notoriously hard. A visual tester lets you iterate quickly, see exactly what your pattern matches, and validate it before embedding it in code.

How to Use the Regex Tester — Step by Step

1. 1

   Enter pattern

   Type your regular expression (no slashes needed).

2. 2

   Set flags

   Optionally add i (case-insensitive), m (multiline), or s (dot matches newline).

3. 3

   Enter test string

   Paste or type the text you want to check.

4. 4

   Test

   All matches are highlighted in the output; details show position and captured groups.

Frequently Asked Questions

Which regex flavour is used?

Python's built-in re module, which is compatible with most standard PCRE patterns.

What are flags?

Flags modify pattern behaviour: i = case-insensitive, m = ^ and $ match start/end of each line, s = dot matches newline characters.

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