Background knowledge and practical explanations for the topics our tools cover — from cryptography to travel and visa rules, web standards, and security.
A short guide to hash algorithms: what makes MD5 insecure, what SHA-256 does better, and when to use which algorithm.
Read more →BMI is simple but has blind spots. We compare it with methods for measuring body fat percentage — and explain when each metric is useful.
Read more →How the rolling 180-day window actually works, common myths, and a few examples for visa-free travelers.
Read more →Header.Payload.Signature, signing algorithms, common claims, and security pitfalls — a practical intro to JWT.
Read more →The 5-field syntax, special characters, common patterns, and typical pitfalls — from the classic @daily to the Quartz variant.
Read more →Entropy, brute force, Diceware passphrases, password managers, and 2FA — everything that belongs to a modern password strategy.
Read more →