Regex Generator
Set your conditions like building blocks and generate a practical regex immediately, with live test feedback.
Required Contents
Allowed Character Set
Flags and Anchors
Tip: if you want strict format validation, keep "allow only selected sets" enabled and keep both ^ and $.
- Choose character sets under "Allowed Characters" (lowercase, uppercase, digits, symbols, and more).
- Set required character conditions under "Must Include".
- Set min/max length, flags, and anchors (^ / $).
- Type in "Test String" to check matching in real time.
- Or use "Quick Presets" for common patterns like email and URL.
When would you use this?
- Quickly build validation rules for email or phone number formats
- Filter or extract specific text patterns in code
- Test whether an existing regex matches as expected
What is a regular expression (Regex)?
A regex is a syntax for describing text patterns, commonly used to search, validate, or replace strings that match a specific format — widely used in programming and data processing.
What do the flags do?
i ignores case, m makes ^ and $ match the start/end of each line, s lets . match newlines, and u enables Unicode mode. Check the flags you need.
What is greedy matching?
By default, regex uses greedy mode and matches as much as possible. To match the shortest result, add ? after a quantifier (e.g., .+? for non-greedy).
Can the generated regex be used directly in code?
Yes. The generated regex follows ECMAScript standards and works in JavaScript, Python, PHP, and other major languages. Always verify the behavior using the test field before deploying.
Complete Regular Expression Guide: From Basics to Practical Applications
Regular Expression (Regex) is the most powerful text processing tool in modern programming. This comprehensive guide covers symbol meanings, common patterns, advanced techniques, and practical applications to help you master regex for data validation, extraction, and replacement.
URL Encoding Guide: Percent-Encoding, Pitfalls, and Practical Patterns
URL encoding looks simple, but it often causes broken parameters, double-encoding bugs, and subtle security issues. This guide explains percent-encoding rules, encodeURI vs encodeURIComponent, and reliable API workflows.