RegEx Tester

User Guide

Overview

The RegEx Tester is a powerful tool for testing and debugging regular expressions. It provides real-time matching with visual highlighting, detailed match information, capture group extraction and support for all standard regex flags.

When to Use RegEx Tester

Pattern Development: Build and test regex patterns before using them in code
Data Validation: Verify patterns for email, phone, URL or custom format validation (for JSON validation, try our JSON Validator)
Text Extraction: Test patterns for extracting specific data from text
Debugging: Troubleshoot why a regex pattern isn't matching as expected
Learning: Understand how different regex features and flags work
Documentation: Create examples and test cases for regex patterns

How to Use

1. Enter Pattern: Type your regular expression pattern in the regex input field
2. Select Flags: Choose appropriate flags (g, i, m, s, u) for your use case
3. Add Test String: Enter or paste the text you want to test against
4. Test: Click "Test Regex" to see matches, capture groups and positions
5. Review Results: Examine highlighted matches, match count, and capture group details

Common Examples

Email Validation

Pattern: [a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}
Flags: i (case insensitive)

Test String:
Contact us at support@datamatastudios.com or sales@example.org

Matches:
- support@datamatastudios.com
- sales@example.org

Phone Number (US)

Pattern: (\d{3})-(\d{3})-(\d{4})
Flags: g (global)

Test String:
Call 555-123-4567 or 555-987-6543 for support

Matches:
- 555-123-4567 (Groups: 555, 123, 4567)
- 555-987-6543 (Groups: 555, 987, 6543)

Extract URLs

Pattern: https?://[^\s<>"{}|\\^[`]+
Flags: g (global)

Test String:
Visit https://datamatastudios.com or http://example.org for more info

Matches:
- https://datamatastudios.com
- http://example.org

Date Format (YYYY-MM-DD)

Pattern: (\d{4})-(\d{2})-(\d{2})
Flags: g (global)

Test String:
Events: 2024-01-15, 2024-03-22, 2024-12-31

Matches:
- 2024-01-15 (Groups: 2024, 01, 15)
- 2024-03-22 (Groups: 2024, 03, 22)
- 2024-12-31 (Groups: 2024, 12, 31)

Find Whole Words

Pattern: \bdata\b
Flags: gi (global, case insensitive)

Test String:
Data professionals use data analysis to extract database insights.

Matches:
- Data (position 0)
- data (position 25)

Use Cases

Web Development

Validate form inputs (emails, phones, URLs), parse API responses, extract data from HTML and sanitize user input.

Data Processing

Clean messy data, extract structured information from text, standardize formats, and filter records.

Log Analysis

Parse log files, extract timestamps and error codes, filter by patterns and identify anomalies.

Text Search

Find patterns in documents, replace text with complex rules, extract mentions or hashtags and validate formats.