ISO 3166-1 Alpha-2 Country Code Regex for Go

What this pattern does

This page provides a lightweight, single-purpose regular expression for matching iso 3166-1 alpha-2 country code, ported and verified for Go. A rigorously tested regex reduces debugging time and protects your application from edge-case failures. 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

// ISO 3166-1 Alpha-2 Country Code
// ReDoS-safe | RegexVault — Localization > Locale & Language

package validation

import "regexp"

var iso31661Alpha2CountryCodeRe = regexp.MustCompile(`^[A-Z]{2}$`)

func ValidateIso31661Alpha2CountryCode(s string) bool {
    return iso31661Alpha2CountryCodeRe.MatchString(s)
}

// Example
// fmt.Println(ValidateIso31661Alpha2CountryCode("US")) // true

Test Cases

When to use this pattern

This pattern is drawn from the Localization > Locale & Language 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

ISO 3166-1 alpha-2 uses uppercase. Exceptions: UK is not a valid code (GB is used for the United Kingdom). XK is used for Kosovo informally. EU is a special supranational code. Validate against the official ISO 3166 Maintenance Agency list.