Articles

Guides and explainers that go with the tools: how the formats work, which trade-offs matter, and when to reach for one approach over another.

2 min read
Hex, RGB, HSL or OKLCH: Which Should You Use?
Four ways to write the same colour, with different strengths. Why HSL lies about brightness, and what OKLCH fixes that the others cannot.
2 min read
How Long Does It Take to Double Your Money?
The rule of 72 answers it in your head, and it is accurate enough to be useful. Where it comes from, where it drifts, and what it quietly assumes.
2 min read
How Long Should a Password Be in 2026?
Why length beats complexity, what entropy actually measures, and how to pick a password length that will still hold up in ten years.
2 min read
How Much Should You Tip? What Custom Actually Says
Tipping norms differ enormously by country, and the reason is structural rather than cultural. How to work out the right amount somewhere unfamiliar.
2 min read
How to Calculate Percentage Change
One formula, and three places people get it wrong: which number goes on the bottom, why increases and decreases are not symmetric, and points versus percent.
2 min read
Is It Safe to Decode a JWT Online?
A decoder can be perfectly safe or quietly disastrous, and the difference is not visible from the page. How to tell, and what to do either way.
2 min read
Passphrase or Random Password: Which Should You Use?
Both can be strong, but they are strong in different ways. Where each one wins, and the mistake that makes most passphrases far weaker than they look.
2 min read
What Is a Unix Timestamp, and Why Does It Start in 1970?
A count of seconds since an arbitrary Tuesday. Why that date was chosen, what the format deliberately ignores, and what breaks in 2038.
2 min read
What Is a UUID, and When Should You Use One?
A plain explanation of what UUIDs are, where version 4 gets its randomness, and when reaching for one beats an auto-incrementing key.
2 min read
Why CSV Is Harder to Parse Than It Looks
Splitting on commas works until the first quoted field, and CSV has no real standard to fall back on. The cases that break naive parsers.
2 min read
Why Do Programmers Use Hexadecimal?
Not because it is closer to how machines work — it is not. Hex survives because of one arithmetic coincidence that makes binary readable to humans.
2 min read
Why Does a Longer Loan Cost So Much More?
A longer term lowers the monthly payment and raises the total by far more than it seems. Where the extra money goes, and how to see the trade clearly.
3 min read
Why Is My JSON Invalid? The Seven Usual Causes
Almost every JSON parse error comes from the same short list of mistakes. Here is each one, why it is tempting, and how to spot it quickly.