Which learning path should I pick?

New to system design: start with System Design Foundations. A system design interview coming up: Interview in 30 Days. Five or more years in and aiming for Staff: Senior/Staff Depth. Building with LLMs: AI Engineer Foundations, then Production Agents.

Are the learning paths free?

Every path page is free, and every path starts with free lessons you can read with no account. The rest of each path's lessons are in a course, which is one payment for lifetime access.

Can I follow more than one path?

Yes. Many lessons appear on more than one path. When you are signed in, a lesson you finish is ticked on every path that uses it.

Do the paths include practice?

Yes. Each path ends with a milestone: a real system to design, using an interview guide, and a mock interview with the AI interviewer, which scores you on ten points with quotes from your own answers.

Learning paths

974 lessons is a lot. Here is the order to read them in.

Five paths, each for one kind of reader. Each one names the exact lessons, in order, says how long they take, shows which are free, and ends with a milestone you can prove: a real system you design and defend in a mock interview.

pick one · start free · tick them off as you go

The paths are free to follow, and each starts with free lessons. The rest are in two courses, one payment each, lifetime access: System Design $49 · AI Engineering $49.

See both courses

System Design5 steps, week by week · about 14 hours

System Design Foundations

For: career switchers, junior developers, and anyone who builds with AI and wants to know what runs underneath
Goal: Understand the core building blocks
First milestone: Design a scalable read-heavy web app, like a URL shortener, and defend it in a mock interview.

29 lessons (10 free) · 1 interview guide · 1 mock interview

See the Beginner path

System Design30 days · about 28 hours

Interview in 30 Days

For: anyone with a system design round already on the calendar
Goal: Prepare efficiently
First milestone: Finish the framework (days 1 to 10), ten common systems, and three mock interviews.

50 lessons (7 free) · 13 interview guides · 3 mock interviews

See the Interview in 30 days path

System Design6 steps, week by week · about 18 hours

Senior/Staff Depth

For: engineers five or more years in, filling the gaps before a Staff or Principal loop
Goal: Reason about trade-offs and failures
First milestone: Consistency, consensus, multi-region and observability, finished with a staff-level mock interview.

37 lessons (0 free) · 1 mock interview

See the Senior to Staff depth path

AI Engineering5 steps, week by week · about 24 hours

AI Engineer Foundations

For: engineers shipping LLM features, RAG or agents to real users
Goal: Build production AI systems
First milestone: A RAG baseline and an eval harness that tells you when it gets worse.

25 lessons (3 free) · 1 interview guide · 1 mock interview

See the AI Engineer path

AI Engineering5 steps, week by week · about 27 hours

Production Agents

For: engineers putting AI agents in front of real users, with real tools and real data
Goal: Ship controlled agents
First milestone: A tool loop, a governor (limits on steps, time and money), tracing, and human approval.

25 lessons (2 free) · 1 interview guide · 1 mock interview

See the Production agents path

Questions

Which learning path should I pick?: New to system design: start with System Design Foundations. A system design interview coming up: Interview in 30 Days. Five or more years in and aiming for Staff: Senior/Staff Depth. Building with LLMs: AI Engineer Foundations, then Production Agents.
Are the learning paths free?: Every path page is free, and every path starts with free lessons you can read with no account. The rest of each path's lessons are in a course, which is one payment for lifetime access.
Can I follow more than one path?: Yes. Many lessons appear on more than one path. When you are signed in, a lesson you finish is ticked on every path that uses it.
Do the paths include practice?: Yes. Each path ends with a milestone: a real system to design, using an interview guide, and a mock interview with the AI interviewer, which scores you on ten points with quotes from your own answers.

Every path runs through one of two courses. Both, at your price.

Paths 1 to 3

System Design Masterclass

770 lessons · about 283 hours · 18 free to read

$49 once, lifetime access · pay with PayPal

Get System Design · $49 Read 18 lessons free first

Paths 4 and 5

AI Engineering

204 lessons · about 211 hours · 10 free to read

$49 once, lifetime access · pay with PayPal

Get AI Engineering · $49 Read 10 lessons free first

Either course includes the AI tutor beside every lesson, 10 questions a day, and the full seven-stage mock interview. Try a mock interview

Learning paths

974 lessons is a lot. Here is the order to read them in.

pick one · start free · tick them off as you go

The paths are free to follow, and each starts with free lessons. The rest are in two courses, one payment each, lifetime access: System Design $49 · AI Engineering $49.

See both courses

System Design5 steps, week by week · about 14 hours

System Design Foundations

For: career switchers, junior developers, and anyone who builds with AI and wants to know what runs underneath
Goal: Understand the core building blocks
First milestone: Design a scalable read-heavy web app, like a URL shortener, and defend it in a mock interview.

29 lessons (10 free) · 1 interview guide · 1 mock interview

See the Beginner path

System Design30 days · about 28 hours

Interview in 30 Days

For: anyone with a system design round already on the calendar
Goal: Prepare efficiently
First milestone: Finish the framework (days 1 to 10), ten common systems, and three mock interviews.

50 lessons (7 free) · 13 interview guides · 3 mock interviews

See the Interview in 30 days path

System Design6 steps, week by week · about 18 hours

Senior/Staff Depth

For: engineers five or more years in, filling the gaps before a Staff or Principal loop
Goal: Reason about trade-offs and failures
First milestone: Consistency, consensus, multi-region and observability, finished with a staff-level mock interview.

37 lessons (0 free) · 1 mock interview

See the Senior to Staff depth path

AI Engineering5 steps, week by week · about 24 hours

AI Engineer Foundations

For: engineers shipping LLM features, RAG or agents to real users
Goal: Build production AI systems
First milestone: A RAG baseline and an eval harness that tells you when it gets worse.

25 lessons (3 free) · 1 interview guide · 1 mock interview

See the AI Engineer path

AI Engineering5 steps, week by week · about 27 hours

Production Agents

For: engineers putting AI agents in front of real users, with real tools and real data
Goal: Ship controlled agents
First milestone: A tool loop, a governor (limits on steps, time and money), tracing, and human approval.

25 lessons (2 free) · 1 interview guide · 1 mock interview

See the Production agents path

Questions

Which learning path should I pick?: New to system design: start with System Design Foundations. A system design interview coming up: Interview in 30 Days. Five or more years in and aiming for Staff: Senior/Staff Depth. Building with LLMs: AI Engineer Foundations, then Production Agents.
Are the learning paths free?: Every path page is free, and every path starts with free lessons you can read with no account. The rest of each path's lessons are in a course, which is one payment for lifetime access.
Can I follow more than one path?: Yes. Many lessons appear on more than one path. When you are signed in, a lesson you finish is ticked on every path that uses it.
Do the paths include practice?: Yes. Each path ends with a milestone: a real system to design, using an interview guide, and a mock interview with the AI interviewer, which scores you on ten points with quotes from your own answers.

Every path runs through one of two courses. Both, at your price.

Paths 1 to 3

System Design Masterclass

770 lessons · about 283 hours · 18 free to read

$49 once, lifetime access · pay with PayPal

Get System Design · $49 Read 18 lessons free first

Paths 4 and 5

AI Engineering

204 lessons · about 211 hours · 10 free to read

$49 once, lifetime access · pay with PayPal

Get AI Engineering · $49 Read 10 lessons free first

Either course includes the AI tutor beside every lesson, 10 questions a day, and the full seven-stage mock interview. Try a mock interview