Close your skill gaps with resources that actually exist.

Martin Fowler’s guide to what to test, at which level, and why.

The official book: ownership, types, error handling, concurrency and tooling.

A popular open-source guide to designing large-scale systems and preparing for system design interviews.

A concise methodology for building deployable, scalable software-as-a-service applications.

The official guide to TypeScript’s type system for JavaScript developers.

OWASP’s introduction to identifying, analysing and mitigating threats in a system design.

PortSwigger’s free, hands-on training with labs on web vulnerabilities.

MIT OpenCourseWare’s full course with lecture videos, notes and problem sets.

Google’s free book on running production systems: SLOs, monitoring, incidents and release engineering.

Stanford’s graduate course on natural language processing, with lecture material online.

A series of practical exercises that teach real-world cryptography by breaking it.