Domain Name (Basic Hostname) Regex for Go

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching domain name (basic hostname), 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

// Domain Name (Basic Hostname)
// ReDoS-safe | RegexVault — Web & Network > Domain

package validation

import "regexp"

var domainNameBasicHostnameRe = regexp.MustCompile(`^(?:[a-zA-Z0-9](?:[a-zA-Z0-9\-]{0,61}[a-zA-Z0-9])?\.)*[a-zA-Z0-9](?:[a-zA-Z0-9\-]{0,61}[a-zA-Z0-9])?$`)

func ValidateDomainNameBasicHostname(s string) bool {
    return domainNameBasicHostnameRe.MatchString(s)
}

// Example
// fmt.Println(ValidateDomainNameBasicHostname("example.com")) // true

Test Cases

When to use this pattern

This pattern is drawn from the Web & Network > Domain 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

Does not validate TLD existence or length. Each label limited to 63 chars per RFC 1034. Total hostname should be ≤253 chars (not enforced here).