Handbook
Developer courses
Structured textbooks for core developer topics. Learn the subject first, then practice with related tools.
JSON Course
A structured introduction to JSON: syntax, types, parsing, generation, real-world patterns, and ecosystem tradeoffs.
Base64 Course
Learn Base64 encoding from first principles: binary-to-text, padding, URLs, and common pitfalls.
URL Encoding Course
Understand percent-encoding, query strings, and the difference between encodeURI and encodeURIComponent.
Unix Time & Timestamps Course
Learn Unix epoch time, seconds vs milliseconds, UTC, timezones, ISO 8601, and how to debug timestamps in logs and APIs.
UUID Course
Learn how UUIDs work, when to use v4, how formats differ, and what version and variant mean.
Password Security Course
Learn practical password length, randomness, passphrases, storage, and sharing habits.