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System Design Interview
Go from a blank whiteboard to a clear, defensible system design using a practical step-by-step process.
- Level
- Mid → Senior
- Runtime
- ≈ 4 hours
- Access
- Lifetime
SYSTEM DESIGN
DESIGN FOR SCALE
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Course Overview
Knowing architecture patterns is useful. In an interview, the harder part is deciding what matters now, explaining why and keeping the conversation coherent under time pressure.
You start drawing too early
Without a discovery phase, the architecture solves assumptions rather than the actual problem.
Your decisions sound arbitrary
Naming Kafka, Redis or microservices is not enough when the interviewer asks why they belong.
You lose the thread
A large design quickly becomes a collection of disconnected boxes without a repeatable narrative.
You run out of time
Candidates often over-invest in one detail and leave reliability, bottlenecks or trade-offs untouched.
Now imagine
A repeatable process for the entire conversation
Instead of hoping the right idea appears, you move through a deliberate sequence and make your reasoning visible.
- ✓Turn vague prompts into a clear, interview-ready plan.
- ✓Estimate scale and choose components for explicit reasons.
- ✓Explain trade-offs instead of presenting one “perfect” architecture.
- ✓Lead the conversation while staying responsive to interviewer feedback.
Introducing
System Design Interview
The draft course is organized around the three transitions that decide most interviews: understanding the problem, shaping the architecture and defending the trade-offs.
Frame the problem
Clarify the product, define requirements, estimate scale and agree on scope.
- → Requirements
- → Capacity estimates
- → APIs and data model
Build the architecture
Move from a simple end-to-end flow to a design that handles the most important constraints.
- → Core flow
- → Storage
- → Caching and asynchronous work
Defend the trade-offs
Find bottlenecks, discuss failure modes and explain how the design evolves.
- → Failure modes
- → Bottlenecks
- → Follow-up questions
Course experience
What's Inside
These details are placeholders for the first release and will be updated as the curriculum is finalized.
Video lessons
Focused explanations
Short, structured lessons designed for deliberate practice.
Framework
Reusable process
Templates and checklists that work across many system design prompts.
Worked examples
Step by step
See the reasoning process, not only the final architecture diagram.
Lifetime access
One-time purchase
Draft commercial terms for the first CodeWithLucian course release.
Course curriculum
From blank canvas to defended design
A draft curriculum that follows the actual interview flow. Module names and individual lessons will be refined with the final recordings.
Course orientation and interview strategy
Build the mental model and learn how to practise with the course.
- → Stop Memorizing Diagrams
- → The System Design Interview Framework
- → The Backend System Design Map
API boundaries, performance and trust
Understand the decisions at the front door of a backend system.
- → REST API Design
- → REST API Performance
- → How TLS Works
Data, traffic and distribution
Choose storage and distribute load with a reason.
- → Database Models
- → Rate Limiting
- → Consistent Hashing
Specialized systems at scale
Study interaction patterns with unusual latency and connection needs.
- → WebSockets at Scale
- → Search Autocomplete
Complete case studies
Apply the framework to realistic end-to-end systems.
- → How to Approach Case Studies
- → Design Twitter
- → Design Payments
Modern systems and interview readiness
Close with a modern architecture and a reusable final checklist.
- → Bonus: RAG at 10 Million Documents
- → Final Interview Checklist
Course format
Designed for focused, practical study
Short lessons, concrete examples and supporting resources are planned so you can review the framework before an interview without replaying hours of material.
- ✓Concise video lessons with English subtitles.
- ✓Architecture walkthroughs and decision checkpoints.
- ✓Downloadable templates and interview checklists.
- ✓Protected access through your CodeWithLucian account.
The right fit
Who is this course for?
It is designed as an interview and communication course—not as a first introduction to programming.
- ✓Backend engineers preparing for mid-level or senior interviews.
- ✓Engineers who know individual components but need a repeatable design process.
- ✓Candidates who want to communicate trade-offs with more structure and confidence.
- ✓Developers who learn best from worked examples and concrete decision frameworks.
Pricing and access
Choose the product that matches your preparation
The course is a one-time purchase. The Question Library remains a subscription, while the Pack combines both products without automatic renewal in v1.
Practice
Interview Question Library
Find your knowledge gaps through focused interview practice.
$12 monthly available
- Full interview question library and answers
- Progress and flags across every topic
- New questions added over time
- First 5 questions in every topic are free
Cancel your subscription at any time.
Learn
System Design Course
Use a practical process to design and defend systems with confidence.
Lifetime access
- Complete video course with English subtitles
- Practical step-by-step interview framework
- Progress tracking and resume
- 6 complete preview lessons
15-day refund policy.
Best ValueLearn + Practice
System Design Interview Pack
Combine the complete course with focused interview practice.
Course lifetime access + 12 months of practice
- Everything in the System Design Course
- 12 months of Question Library access
- Lifetime access to the complete course
- All free previews included
15-day refund policy.
The Course has a secure one-time checkout and a 15-day refund policy. Question Library checkout is available separately; the Pack will be connected in its dedicated task.
Secure one-time purchase
One course. One-time purchase. Lifetime access.
Get the complete System Design Interview course for a one-time $99 payment. Sign in, complete the secure Stripe checkout and start learning immediately.
Lifetime course access · 15-day refund policy · Checkout by Stripe
Student stories
Testimonials
The final page will use substantial comments from Lucian’s YouTube audience. These cards only define the intended layout.
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YouTube learner
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Placeholder for a comment about clarity, practical examples or interview confidence.
Backend engineer
Real testimonial to be selected
Placeholder for a substantial student story rather than generic praise.
Course learner
Real testimonial to be selected
Questions
Frequently Asked Questions
Draft answers for the questions students are most likely to ask before enrollment.
How long is the course?
The first release is planned at approximately four hours. The final runtime will be updated after editing.
Is this course for beginners?
It assumes basic backend development knowledge and focuses on interview reasoning rather than programming fundamentals.
How will I access the course?
Sign in with your CodeWithLucian account, complete the secure Stripe checkout and open the protected learning area immediately after your payment is confirmed.
Is access included with the Question Library subscription?
No. The first version treats the course as a separate one-time purchase.
Your instructor
Meet Lucian Oprea
Lucian is a backend software engineer and educator focused on system design, Java and practical interview preparation. This biography is a draft and will be replaced with the final instructor story before launch.
More about Lucian →Start when you are ready
Prepare a process you can trust under pressure.
Get lifetime access to the full course with one secure payment.