What is Regex Builder?
Regex Builder is a free online tool for visually constructing and testing regular expressions. It provides live match highlighting with color-coded capture groups, a common patterns library for quick insertion, and detailed match breakdowns. Unlike basic regex testers, this builder helps you construct patterns step by step with visual feedback.
Common Use Cases
Pattern Development
Build complex regex patterns incrementally with instant visual feedback on matches and capture groups.
Data Extraction
Craft regex patterns to extract specific data like emails, URLs, dates, or phone numbers from text.
Input Validation
Design and test validation patterns for form fields, API inputs, and configuration values.
Log Analysis
Create patterns to parse and extract structured data from log files and server output.
How to Use This Tool
- Enter your regex pattern in the input field (without delimiters)
- Toggle regex flags (g, i, m, s, u) as needed
- Paste or type your test string in the text area below
- View highlighted matches and capture group details in real-time
- Use the quick patterns bar to insert common patterns like email or URL
- Copy match results as JSON for use in your code