Guides

Engineering guides

These are the topics I keep having to re-explain: what a token actually contains, why a schedule fires more often than intended, which identifier to put in a primary key. Each guide covers one thing properly and hands you the tool that goes with it.

Authentication

What is actually inside a JWT
A JSON Web Token is three base64url segments, and only the third one protects anything. Here is what each part holds, what it does not hide, and the mistakes that follow from getting that backwards.
Beginner·9 min·2026-09-08

Scheduling

Cron expressions explained, including the trap
Five fields, a handful of operators, and one rule that makes cron fire far more often than people expect. Day-of-month and day-of-week are combined with OR, not AND.
Beginner·8 min·2026-09-07

Databases

UUID v4 or v7 as a database key
Random primary keys fragment an index and slow inserts as a table grows. UUID v7 puts a timestamp in the leading bits so new rows land at the end. Here is the trade-off, including what v7 gives away.
Intermediate·7 min·2026-09-06

Built in public.

Progress, revenue and mistakes get posted as they happen rather than saved up for a launch.

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Engineering guides

Authentication

What is actually inside a JWT

Scheduling

Cron expressions explained, including the trap

Databases

UUID v4 or v7 as a database key

Built in public.