Guides & deep dives
Plain-language write-ups on the formats and algorithms behind our tools — how they work, where they break, and what to actually use them for. Written by the person who builds the tools, not spun up to fill a page.
Base64 Explained: What It Actually Does and Where It Breaks
A practical, from-the-bytes-up guide to Base64: why it exists, how the 3-to-4 character mapping works, why UTF-8 trips up naive encoders, what URL-safe means, and the security mistake almost everyone makes at least once.
Reading a JWT: What the Three Parts Actually Contain (and What They Do Not)
A JSON Web Token looks like random noise, but it is three Base64url segments doing three different jobs. This guide shows how to decode one by hand, what the header and payload claims really mean, why the signature is not encryption, and the verification mistakes that cause real vulnerabilities.
The WCAG Contrast Ratio: The Formula, the Thresholds, and the Traps
Color contrast is the most measurable part of accessibility, yet the numbers are widely misunderstood. This guide walks through the actual relative-luminance formula, why AA is 4.5:1 and AAA is 7:1, how large text gets a pass, and the cases where a passing ratio still yields unreadable text.
Unix Timestamps: Seconds, Milliseconds, and the Bugs They Cause
A timestamp like 1700000000 is unambiguous — until you forget whether it is seconds or milliseconds, or assume it means local time. This guide explains what a Unix timestamp really counts, why three-digit and thirteen-digit values behave differently, and the timezone and DST traps that break date math.