// The System Design Primer

Become elite at
system design.

SD Primer is your daily system design coach — delivering drills, AI-guided challenges, and structured learning paths that build real system design interview intuition, not just tricks.

Start Learning Free See How It Works

Client

Load Balancer

API Gateway

Auth Service

Core Service

Cache Layer

PostgreSQL

Message Queue

fig. 01 — distributed system architecture

Format

Daily Training

Focus

Interview Prep

Tracking

Growth Metrics

Audience

Senior Engineers

// Features

Everything you need to master system design

From daily drills to AI-guided challenges, SD Primer covers every angle of system design mastery.

Daily MCQ Drills

One carefully curated system design question every day. Build consistency with bite-sized learning that compounds over time.

System Design Lab

Patch broken architecture diagrams in 3-5 minute visual challenges. Face AI-guided follow-up questions that sharpen your thinking.

Signal Tips

60-second interview tips after each question. Learn the key idea, common mistakes, and exactly how a senior engineer would phrase it.

Streak & XP System

Track your daily streak, earn XP, level up, and unlock achievements. Make consistent learning feel like progress, not a chore.

Coding Patterns

Master essential patterns like Sliding Window, Two Pointers, BFS, DFS, and Dynamic Programming with targeted practice sets.

Industry Awareness

Stay current with curated news across AI, architecture, security, and hiring trends. Know what senior engineers are talking about.

// System Design Lab

Patch real architecture under pressure

The Lab gives you a broken system and a ticking clock. Drag components onto the architecture diagram to fix it, then defend your solution to an AI reviewer.

Read the incident briefing

Understand what went wrong in the system

Patch the architecture diagram

Add components to fix the broken system

Defend your fix to the AI reviewer

Answer follow-up questions about your design decisions

Get scored with detailed feedback

Tradeoffs, key takeaways, and reasoning quality

lab — incident challenge

lab — ai review

patterns — two pointers

// Coding Patterns

Recognize the pattern, solve any problem

Most coding interview problems are variations of ~15 core patterns. Train your pattern recognition daily so the solution becomes obvious before you write a single line of code.

Sliding Window

Two Pointers

Binary Search

BFS & DFS

Hash Map

Dynamic Programming

Greedy

Monotonic Stack

Union-Find

Backtracking

// Beyond Interviews

Tools to accelerate your entire engineering career

SD Primer isn't just interview prep. It's a daily operating system for engineers who want to think, communicate, and ship like senior staff.

mastery

Workplace Mastery

Daily scenarios that teach you how to navigate real engineering situations — from pushing back on feature requests to communicating tradeoffs.

cheatsheet

Interview Cheat Sheet

A step-by-step playbook used by top engineers to ace any coding interview. Master the process, not just the problems.

take-home

Take-Home Guide

A checklist of best practices that top candidates follow to make their take-home project submissions stand out.

// Stay Informed

AI-summarized news for busy engineers

Curated articles across AI, architecture, security, hiring, and startups — each with an AI-generated summary and key takeaways. Know what senior engineers are talking about without drowning in feeds.

AI Architecture Security Hiring Startups Career Tech

news — daily digest

// Why It Works

Consistency beats cramming. Every time.

Bite-Sized Daily Sessions

Two minutes a day. That's all it takes to keep your streak alive and your system design skills sharp.

Spaced Repetition

Our smart queue resurfaces topics at optimal intervals, so knowledge sticks for interviews and beyond.

Career-Relevant Content

Every question maps to real-world scenarios you'll face in senior and staff-level interviews.

Visible Progress

Watch your streak grow, your XP accumulate, and your topic mastery expand — proof that daily effort compounds.

results — ai feedback

results — detailed analysis

// Testimonials

Engineers who level up daily

“

SD Primer made system design click for me. The daily format means I actually stick with it — unlike courses I'd abandon after week two.

Alex Chen

Senior Software Engineer

“

The incident lab challenges are brilliant. Patching architecture diagrams under pressure is exactly the kind of practice that translates to real interviews.

Priya Sharma

Staff Engineer

“

I went from dreading system design rounds to looking forward to them. The Signal Tips alone are worth it — finally, interview-ready phrasing.

Marcus Johnson

Engineering Manager

// FAQ

Frequently asked questions

What is system design?

System design is the process of defining the architecture, components, modules, interfaces, and data flow of a system to satisfy specified requirements. It covers topics like scalability, load balancing, caching, databases, and distributed systems. System design skills are essential for senior and staff-level engineering roles and are a core part of technical interviews at top companies.

What is a system design primer?

A system design primer is a comprehensive resource that teaches the fundamentals of designing large-scale distributed systems. SD Primer takes this further by combining structured learning with daily practice — covering scalability, databases, caching, load balancing, networking, and security through interactive drills and AI-guided challenges.

How do I prepare for a system design interview?

The best way to prepare for a system design interview is consistent daily practice. SD Primer acts as your personal system design coach — delivering daily MCQ drills, AI-guided incident challenges where you patch real architecture diagrams, and signal tips that teach you exactly how to phrase your answers. Start with the fundamentals in our free System Design Primer guide, then build interview-ready intuition through daily training.

Is SD Primer free?

SD Primer offers free daily system design training including MCQ drills, news, and learning content. The System Design Primer guide with all 9 chapters is completely free to read on the web. Premium features like the System Design Lab with AI-guided challenges are available through the iOS app.

Who is SD Primer for?

SD Primer is built for software engineers preparing for senior, staff, and principal-level interviews at top tech companies. Whether you're studying system design for the first time or sharpening existing skills, the daily training format helps you build lasting intuition rather than cramming before interviews.

Become elite atsystem design.