Regex Tester & Validator
Test and validate regular expressions with live pattern matching. Perfect for string validation, data extraction, and text processing.
How to Use the Regex Tester
Step 1: Enter Pattern
Type your regular expression pattern in the regex field. Start with simple patterns like hello or \d+ for numbers.
Step 2: Set Flags
Add flags for behavior: g (global), i (case-insensitive), m (multiline), s (dotall).
Step 3: Test Text
Enter test text to match against your pattern. Matches appear automatically and can be copied for use in your code.
Regular Expression Basics
Regular expressions (regex) are powerful patterns used for searching, matching, and manipulating text. They're supported in most programming languages and text editors.
Common Patterns
\d- Any digit (0-9)\w- Word character (a-z, A-Z, 0-9, _)\s- Whitespace character.- Any character except newline+- One or more*- Zero or more?- Zero or one
Frequently Asked Questions
What are regex flags and when should I use them?
Flags modify how the regex engine processes your pattern. Use g to find all matches (not just the first), i for case-insensitive matching, m to treat each line separately, and s to make . match newlines.
How do I match email addresses?
Try this pattern: [a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}. This matches most email formats, though complete email validation requires more complex patterns.
What's the difference between + and * quantifiers?
+ means "one or more" (requires at least one match), while * means "zero or more" (can match nothing). Use + when you need at least one occurrence, * when the pattern is optional.
How do I escape special characters?
Use backslash (\) before special characters like . + * ? ^ $ { } [ ] | \ ( ). For example, to match a literal period, use \. instead of .
Can I test regex for different programming languages?
Our tester uses JavaScript regex engine, which is similar to most languages but may have slight differences. The core patterns work across Python, Java, C#, PHP, and other languages, though some advanced features may vary.
Common regex examples
Useful patterns for everyday tasks:
- Phone number:
\d{3}-\d{3}-\d{4} - URL:
https?://[^\s]+ - Date (YYYY-MM-DD):
\d{4}-\d{2}-\d{2} - Hex color:
#[0-9A-Fa-f]{6} - Word boundaries:
\bword\b