How to Test Regex Online

Quick guide · 2 min read

Quick Answer

Use an online regex tester to write, test, and debug regular expressions in real-time. See matches highlighted instantly as you type.

Regex Tester

Test regular expressions with real-time matching

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Common Use Cases

  • Complex patterns - Regex syntax can be confusing, especially for complex patterns
  • Debugging - Finding why a pattern doesn't match as expected
  • Learning - Understanding how regex engines process patterns
  • Validation - Ensuring patterns work before deploying to production

Step-by-Step Guide

  1. Enter your regex pattern - Type your regular expression in the Regex Tester
  2. Add test strings - Enter sample text to test against your pattern
  3. See matches instantly - The tool highlights all matches in real-time, helping you debug and refine your pattern

Example

Input:

\d{3}-\d{3}-\d{4}

Output:

Matches: 123-456-7890, 555-123-4567

Frequently Asked Questions

What is a regex tester? ▼
A regex tester is a tool that lets you write and test regular expressions against sample text. It shows matches in real-time, helping you debug and refine your patterns.
Why use an online regex tester? ▼
Online regex testers provide instant feedback, syntax highlighting, and explanations. They're faster than testing in code and help you understand patterns better.
What regex flavors are supported? ▼
Most online regex testers support JavaScript regex, which is similar to PCRE. Some also support Python, PHP, and other flavors. Check the tool's documentation.
How do I escape special characters in regex? ▼
Special characters like . * + ? ^ $ { } [ ] \ | ( ) need to be escaped with a backslash. For example, to match a literal dot, use \.