Courses

Connect to remote machines securely, use keys instead of passwords, copy files, open tunnels and harden a server.

Beginner 6 lessons, 60 min

You can use a terminal and want to manage remote servers safely.

What a hash is, how it differs from encryption, how passwords should be stored and how to verify a download.

Beginner 4 lessons, 36 min

You build or use software that handles passwords, downloads or checksums.

What a JSON Web Token is, how it is built, how signatures work and the mistakes that cause security bugs.

Intermediate 3 lessons, 28 min

You work with APIs or logins and keep seeing long strings starting with "eyJ".

How names become addresses, what each record type does, why changes take time and how to query DNS yourself.

Beginner 4 lessons, 42 min

You own a domain or manage servers and want DNS to stop feeling like magic.

What a large language model is, how tokens and context windows work and how to estimate what an API will cost you.

Beginner 4 lessons, 40 min

You are about to use an AI API in a project and want to understand tokens and pricing before you get a bill.