Anthropic API Key Regex for PHP

What this pattern does

This page provides a well-structured, multi-part regular expression for matching anthropic api key, ported and verified for PHP. In security-sensitive code, using an unverified regex can open the door to both false positives and denial-of-service attacks. The snippet below is ready to drop into your PHP project — whether you're validating in a Laravel validator, a WordPress plugin, or a standalone PHP script.

Php Implementation

<?php
// Anthropic API Key
// ReDoS-safe | RegexVault — Security > API Keys & Tokens

define('ANTHROPIC_API_KEY_PATTERN', '/^sk-ant-[A-Za-z0-9_\-]{32,128}$/');

function validate_anthropic_api_key(string $input): bool {
    return (bool) preg_match(ANTHROPIC_API_KEY_PATTERN, $input);
}

// Example
var_dump(validate_anthropic_api_key("sk-ant-api03-aBcDeFgHiJkLmNoPqRsTuVwXyZ0123456789aBcDe")); // bool(true)

Test Cases

When to use this pattern

This pattern is drawn from the Security > API Keys & Tokens category and carries a ReDoS-safe certification. That matters for PHP developers because especially relevant in PHP where PCRE backtracking limits can trigger silent failures on malicious input. 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

Anthropic API keys use the sk-ant- prefix. Scoped to the organization. If leaked, immediately rotate at console.anthropic.com. Fine-grained API key scopes are available in the Anthropic Console.