5 Common Regex Patterns Every Developer Needs

Regex: The Developer's Superpower

Regular Expressions (Regex) are intimidating but incredibly powerful. A single line of regex can replace dozens of lines of string parsing code. Here are 5 patterns you'll use constantly in web development.

Tip: Test these patterns instantly in our Regex Tester!

1. Email Address Validation

A classic pattern to check if a string looks like an email.

^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$

• ^...$: Anchors to ensure the whole string matches.
• @: The separator.
• \.[a-zA-Z]{2,}: Matches the domain extension (must be at least 2 letters).

2. URL Matching

Grab URLs from a block of text.

https?:\/\/(www\.)?[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()@:%_\+.~#?&//=]*)

• https?: Matches http or https.

3. Password Strength (Complex)

Enforce: Uppercase, Lowercase, Number, Special Char, Min 8 chars.

^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[@$!%*?&])[A-Za-z\d@$!%*?&]{8,}$

• (?=.*[A-Z]): Positive lookahead checking for at least one capital letter.

4. Dates (YYYY-MM-DD)

Validate standard ISO dates.

^\d{4}-(0[1-9]|1[0-2])-(0[1-9]|[12]\d|3[01])$

5. Extract HTML Tags

Find HTML tags (useful for scraping or cleanup).

<[^>]*>

How to Learn Regex?

The best way is to practice. Don't just copy-paste—type these into our Online Regex Tester, change the input text, and see what matches. Understanding why it matches is the key to mastering this skill.