System Design
Build Secure Systems by Default
Design architecture that is secure by design. Place components, draw trust boundaries, and route identity flows on a real canvas — then see your work graded against the invariants that matter.
Guided by The Architect
What it is
System Design, defined
Secure system design is architecture that upholds the invariants that matter — trust zones, least privilege, identity flows — so whole classes of attack simply can't happen. It's the one proactive security discipline: fixing the problem on the whiteboard, before a single line of code is written.
The career
A skill you get hired for
Architecture is the cheapest place to fix a security problem and the most expensive place to ignore one. It's the only discipline that prevents incidents instead of reacting to them.
Builds toward
Security Architect
Typical salary
$165K/yr avg
Market demand
500K+ open US roles
Who you'd work alongside
- Security architects
- Platform, infrastructure, and staff+ engineers
- Teams running secure design reviews and threat models
- Anyone deciding how systems fit together
The DefendTheOrg approach
How you'll learn it
Under The Architect — the only mentor who teaches a proactive discipline — you design on a real canvas: place components, draw trust boundaries, and route identity flows, then see your work graded against the invariants that matter:
Invariants, not topologies
There are many ways to build a system that works, but few that uphold the right invariants — 'the database is unreachable from the internet,' 'all auth crosses an IdP.' You're graded on those.
Think in blast radius
Trust zones, least privilege, and what happens when one component is compromised — you learn to design so failure stays contained.
Catch it before code
Spot the topology-vs-invariant mistakes that senior reviewers reject on sight — before they turn into incidents.
Stuck? Get walked through it.
Every Easy and Medium lab has a walkthrough from The Architect — one hint at a time, with a chance to try each step yourself before the answer. You get three a week, and using one never touches your score. It teaches the reasoning, not the solution.
Try it yourself
A taste of the real lab
This is a simplified, no-signup slice of a System Design lab — make your call and see how it's graded. The real labs go deeper.
Design a secure path
Connect the components so the database stays behind the API.
Drag from a node's edge to another to connect them. Route the traffic so the database is never exposed to the internet.
Push yourself
Where Hard and Expert labs take you
Every skill scales from your first lab to genuinely hard reasoning. Difficulty isn't a bigger wall — it's deeper thinking.
Hard
Hard labs run 18–25 rules across path invariants, identity flows, multi-tenant isolation, and async data paths — with the full component palette and no hints.
Expert
Expert labs go past 25 rules with adversarial constraints and composed invariant families, no reference shape to copy, and a 100% pass bar — you invent the topology and every rule has to hold.
Start system design training
Hands-on labs built from real engagement data. Learn by doing — guided by The Architect.