Developer Guides
JSON vs CSV vs XML: Which Data Format to Use
JSON handles nesting and types, CSV is the leanest choice for tables, and XML carries documents and schemas. Here's how they compare and what breaks when you convert.
Blog
Guides, tips and how-tos for getting more out of free web tools, from formatting JSON to building better passwords.
Developer Guides
Regex for Beginners: 15 Patterns You'll Actually Use
The handful of regex building blocks you need, 15 tested patterns for everyday validation, searching and cleanup, and the mistakes that trip up beginners.
Security & Privacy
How Credit Card Numbers Work: The Luhn Algorithm
Card numbers carry their own typo check. Here's how the Luhn algorithm works step by step, what the leading digits mean, and what a passing check can't tell you.
Everyday Math & Text
How Loan Amortization Works (and What Extra Payments Save)
Why early mortgage payments go mostly to interest, how the payment formula works, and what extra payments really save, worked through on one $300,000 loan.
Web & SEO
UTM Naming Conventions That Keep GA4 Clean
Case-sensitive values, unrecognized mediums and vague campaign names are why GA4 reports get messy. Here are seven rules and a naming sheet you can adopt as-is.
Developer Guides
URL Encoding Explained: %20 vs + and When to Use Each
A space can be %20 or +, depending on where it is. Here's how percent-encoding works, which JavaScript function to use, and how to avoid double encoding.
Developer Guides
The Year 2038 Problem, Explained
Signed 32-bit Unix time runs out at 03:14:07 UTC on January 19, 2038. Here's why, what's already fixed, what's still at risk, and how to check your own systems.
Security & Privacy
Hashing vs Encryption vs Encoding: The Difference
Encoding can be reversed by anyone, hashing can't be reversed at all, and encryption needs a key. Here's one message run through all three, and how to choose.
Everyday Math & Text
Percent Change vs Percentage Points
A rate going from 4% to 5% rose by 1 percentage point, or by 25%. Here's how to calculate each, when to use which, and the mistakes that make numbers misleading.
Web & SEO
Link Preview Not Showing? Fixing Open Graph Images
A missing or outdated link preview almost always comes down to the tags, crawler access, the image itself or a cached copy. Here's how to check each one and force a refresh.
Developer Guides
What Is Base64 Encoding (and Why Is It 33% Bigger)?
Base64 rewrites any bytes using 64 safe text characters. Here's how the encoding works, where the extra third comes from, and where you'll run into it.
Security & Privacy
How Long Should a Password Be? What NIST Now Says
NIST's current guidelines call for at least 15 characters, no forced complexity and no scheduled changes. Here's why length wins, with real numbers for passwords and passphrases.