Guides

Substantive, practical writing about regular expressions and the tools around them. Written for engineers who’d rather understand regex than memorize it.

• Regex 101: a working developer's introduction

  Start here. The minimum mental model you need to read and write regex without copy-pasting Stack Overflow blindly.

  12-min read·Read

• Lookahead vs lookbehind, explained

  Zero-width assertions — what they do, when you actually need them, and the engines that don't support them.

  9-min read·Read

• ReDoS and catastrophic backtracking — how to spot and stop it

  The class of regex bug that took Cloudflare down for 27 minutes in 2019. How to recognize, test, and rewrite vulnerable patterns.

  11-min read·Read