100% Client-Side • 0 B Data Leaves Browser
security
American Express (Amex) Card Regex
Validates 15-digit American Express credit cards starting with prefixes 34 or 37.
Regular Expression Pattern:
/^3[47][0-9]{13}$/
Valid Match Example:
378282246310005
Invalid / Non-Match Example:
388282246310005
Regex Syntax Breakdown & Explanation
- •^3[47] : Amex cards strictly begin with either 34 or 37
- •[0-9]{13}$ : Exactly 13 digits follow for a 15-digit total card number
Implementation in Popular Languages
JavaScript / TypeScript
const regex = /^3[47][0-9]{13}$/;
const isValid = regex.test("378282246310005");
console.log(isValid); // truePython (re)
import re
pattern = r"^3[47][0-9]{13}$"
match = re.match(pattern, "378282246310005")
print(bool(match)) # TrueGo (regexp)
package main
import (
"fmt"
"regexp"
)
func main() {
re := regexp.MustCompile(`^3[47][0-9]{13}$`)
fmt.Println(re.MatchString("378282246310005"))
}Frequently Asked Questions
Frequently Asked Questions
Everything you need to know regarding specifications, syntax, and security best practices.
The regular expression pattern is /^3[47][0-9]{13}$/. Validates 15-digit American Express credit cards starting with prefixes 34 or 37.