Regex Tester
Updated on:Test regular expressions online with match highlighting.
How it works
1. Enter pattern. 2. Enter text. 3. Choose flags. 4. Click Test.
Advantages
Instant matching. Group display. Flag support i, m, s. Timeout protection.
Common mistakes to avoid
- Escaping special characters: . * + ? | ( ) [ ] { } \ have special meaning. To search them literally, use backslash: \. \* etc.
- Greedy vs lazy: .* is greedy (captures as much as possible). Use .*? for lazy matching (as little as possible).
- Differences between engines: JavaScript, Python, .NET and PCRE regex have subtle differences. This tool uses JavaScript.
- Performance: complex regex with lots of backtracking can be very slow ("catastrophic backtracking"). Test on small inputs first.
- Multiline: by default, ^ and $ match the start/end of the entire string. With the m flag, they match start/end of each line.
Description
Online Regular Expression Tester
Our regex tester lets you test and verify regular expressions in real time. Regular expressions are patterns used to search, validate and manipulate text strings, fundamental in software development.
Features
- Real-time testing
- Match highlighting
- Supported flags (global, case-insensitive, multiline)
Uses
Email, phone, URL validation. Data extraction, advanced find & replace, log parsing.
FAQ
Standard flags are supported: 'i' (case insensitive), 'm' (multiline) and 's' (dotAll, dot matches newlines too). You can combine them freely.
Yes, capture groups (both numbered and named) are fully supported. The tester shows both the full match and the individual captured groups.
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Category
Web/Dev ToolsSommario