Regex for username

Note

Starts with a letter, then 3–16 characters in total of letters, digits and underscores. Adjust the {2,15} for other lengths.

Matches in the example

• "ana_92"
• "Bob"

Token by token

1. ^ the start of the string (or line, with the m flag)
2. [a-zA-Z] one of: “a” to “z” or “A” to “Z”
3. [a-zA-Z0-9_]{2,15} one of: “a” to “z”, “A” to “Z”, “0” to “9” or “_”, between 2 and 15 times, as many as possible
4. $ the end of the string (or line, with the m flag)

Other patterns

• Email address
• URL
• IPv4 address
• UUID
• Hex color
• Date (YYYY-MM-DD)
• Time (24-hour)
• US phone number
• Phone number (E.164)
• US ZIP code
• Credit card number
• URL slug
• Username
• Strong password
• HTML tag
• Semantic version
• MAC address
• JSON Web Token
• Hashtag
• @mention
• Number
• Leading and trailing whitespace
• Repeated word
• Blank lines
• Markdown link
• Quoted string
• Domain name
• File extension
• Base64
• Trailing comma