Slack Bot / Webhook Token Regex for PHP

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching slack bot / webhook token, 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
// Slack Bot / Webhook Token
// ReDoS-safe | RegexVault — Security > API Keys & Tokens

define('SLACK_BOT_WEBHOOK_TOKEN_PATTERN', '/^(xoxb|xoxp|xoxa|xoxr|xoxs|xapp)-[A-Za-z0-9\-]{10,200}$|^https:\/\/hooks\.slack\.com\/services\/T[A-Z0-9]+\/B[A-Z0-9]+\/[A-Za-z0-9]+$/');

function validate_slack_bot_webhook_token(string $input): bool {
    return (bool) preg_match(SLACK_BOT_WEBHOOK_TOKEN_PATTERN, $input);
}

// Example
var_dump(validate_slack_bot_webhook_token("xoxb-123456789012-123456789012-ABC123def456GHI789jkl0")); // 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

Token prefixes: xoxb=bot token, xoxp=user token, xoxa=app-level token (legacy), xoxr=refresh token, xoxs=workspace token (legacy), xapp=Socket Mode app token. Webhook URLs are for incoming webhooks only and cannot read messages.