Developer Guides
In-depth technical guides on JSON, regular expressions, Git diffs, JWT tokens, and more — written for working software engineers.
A Developer's Guide to Regular Expressions
Regular expressions are one of the highest-ROI skills a developer can learn. This guide covers syntax, flags, groups, lookaheads, and practical patterns.
Lookaheads and Lookbehinds: The Regex Feature That Finally Makes Sense
Zero-width assertions are the most powerful regex feature most developers avoid. Here is a clear explanation of positive and negative lookaheads and lookbehinds with practical examples.
The 20 Regex Patterns Every Developer Needs (With Explanations)
Most cheat sheets give you the pattern without explaining why it works. Here are 20 essential patterns — email, UUID, semver, JWT, and more — each with a breakdown of how it actually works.
Regex vs String Methods: When Each One Is the Wrong Choice
Most developers have strong opinions about regex but make the same mistake: using it for simple string operations. Here is when regex wins, when it loses, and the hot take you need to hear.
Python vs JavaScript Regex: The Same Syntax, Completely Different Behavior
Developers who use regex in both Python and JavaScript carry a dangerous assumption that the patterns are interchangeable. They are not. Here are every behavioral difference.
Regex Flags Are More Powerful Than You Think — And More Dangerous
The g flag has a stateful side effect that bites even experienced developers. The u flag changes Unicode handling in ways that matter for internationalized apps. Here is every flag explained.
Catastrophic Backtracking: The Regex Bug That Can Take Down Your Server
On July 2, 2019, Cloudflare's global network went down for 27 minutes because of one regex with catastrophic backtracking. This is not theoretical — here is how it works and how to prevent it.
Why Your Form Validation Regex Is Wrong (And What to Do Instead)
Email regex, phone validation, password rules — form validation is where developers write the most buggy regex. Here are the correct patterns and the philosophy that produces better outcomes.
Named Capture Groups Are the Most Underused Regex Feature
Positional capture groups create fragile, unreadable regex. Named groups make patterns self-documenting and refactoring-safe. Here is how to use them across JavaScript and Python.
10 Real-World Regex Problems and How Professionals Solve Them
Regex tutorials teach syntax. Real work throws messy ambiguous problems at you. Here are 10 real scenarios with complete solutions: log redaction, CSV parsing, template variables, and more.