Visa Card Number Regex for Go

What this pattern does

This page provides a lightweight, single-purpose regular expression for matching visa card number, ported and verified for Go. Financial data validation has zero tolerance for false negatives — a missed invalid entry can corrupt downstream calculations. The snippet below is ready to drop into your Go project — whether you're validating in a Gin handler, a gRPC service, or a command-line tool.

Go Implementation

// Visa Card Number
// ReDoS-safe | RegexVault — Finance > Card Numbers

package validation

import "regexp"

var visaCardNumberRe = regexp.MustCompile(`^4[0-9]{12}(?:[0-9]{3})?$`)

func ValidateVisaCardNumber(s string) bool {
    return visaCardNumberRe.MatchString(s)
}

// Example
// fmt.Println(ValidateVisaCardNumber("4111111111111111")) // true

Test Cases

When to use this pattern

This pattern is drawn from the Finance > Card Numbers category and carries a ReDoS-safe certification. That matters for Go developers because Go's RE2 engine is inherently safe from catastrophic backtracking, but this pattern has been additionally verified for correctness. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

Visa uses prefix 4. 13-digit Visa cards are legacy (some still in circulation). 16-digit is standard. Luhn validation required separately. Input should have spaces/hyphens stripped before matching.