System Design Fundamentals
Learn the core building blocks of scalable systems (load balancing, caching, databases, APIs) in a beginner-friendly, text-based course. From the creators of Grokking the System Design Interview.
Level:
Beginner
Study Time:
20h
Lessons:
171
Assessments:
381
Updated
Last month
4.5
(31,161 ratings)
93,484 learners
Created byArslan Ahmad
Ex FAANG Manager, Expert Behind System Design FundamentalsCourse Overview
System Design Fundamentals is a beginner-friendly system design course that teaches the core building blocks of scalable systems. You will learn how load balancing, caching, CDNs, databases, data partitioning, and replication work, and when to use each one. Every chapter covers one concept. It explains what problem that part solves, what trade-offs it brings, and how it fits into a larger distributed system. You also learn the ideas that tie it all together, including the CAP theorem, back-of-the-envelope estimation, messaging with Kafka, and system design security basics like OAuth and JWT. This course is built for software engineers, CS students, and backend developers who are new to distributed systems. It is also the ideal starting point for your first system design interview. With 171 lessons, flashcards, and an adaptive assessment in every chapter, you build real understanding, not just vocabulary. You only need basic programming knowledge to begin. Once you finish, you will have the solid foundation needed for Grokking the System Design Interview and for designing systems that stay fast, reliable, and available as they grow.
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Best value
Lifetime access to this course
One-time payment. Yours forever.
Discussions
Certificate
Free updates
Want all 42+ courses?
What you'll learn in System Design Fundamentals
- Master the core building blocks of scalable systems: load balancing, caching, CDNs, and databases.
- Estimate QPS, storage, and bandwidth with back-of-the-envelope math before you design anything.
- Learn how database indexes work, from B-tree internals to LSM trees and distributed indexes.
- Use the CAP and PACELC theorems to reason about consistency and availability trade-offs.
- Protect systems with rate limiting, authentication, authorization, OAuth vs. JWT, and encryption.
- Reinforce every chapter with flashcards and an adaptive assessment, then take a final course quiz.
- Understand how the web works, from DNS and TCP to what happens when you type a URL into the browser.
- Compare SQL and NoSQL databases and understand ACID vs. BASE, normalization, and federation.
- Scale data with partitioning, sharding, redundancy, and replication, and know their trade-offs.
- Build real-time features with long-polling, WebSockets, and Server-Sent Events.
- Learn distributed patterns like quorum, heartbeat, and Bloom filters, plus messaging with Kafka.
- Build the foundation you need before taking Grokking the System Design Interview.
Course Content
2.
Key Characteristics of Distributed Systems
9 lessons
Scalability
Understand scalability in system design, covering vertical and horizontal scaling, stateless servers, caching, replication, sharding, and bottlenecks.
Availability
Understand availability in system design, covering the nines, single points of failure, redundancy, failover, MTBF and MTTR, and SLIs, SLOs, and SLAs.
Latency and Performance
Understand latency and throughput in system design, covering where the time goes, p95 and p99 percentiles, caching, data locality, and load balancing.
Concurrency and Coordination
Understand concurrency in distributed systems, covering race conditions, locking, optimistic concurrency control, synchronization, and consistency models.
Monitoring and Observability
Understand monitoring and observability, covering metrics, structured logging, distributed tracing, alerting, anomaly detection, and dashboards.
Resilience and Error Handling
Understand resilience in system design, covering cascading failures, timeouts, retries with backoff, circuit breakers, bulkheads, and degradation.
Fault Tolerance vs. High Availability
Compare fault tolerance and high availability, covering their promises on downtime and data loss, the techniques each uses, and when to choose one.
Flashcards Review
Review the key terms of distributed systems with flashcards on scalability, availability, latency, concurrency, observability, and resilience.
Chapter Assessment
Test what you learned about distributed systems with questions on scalability, availability, latency, concurrency, observability, and resilience.
3.
Back-of-the-Envelope Estimation
6 lessons
What Is Back-of-the-Envelope Estimation
Understand what back-of-the-envelope estimation is for, the three rules that keep it fast, how accurate it must be, and where it belongs in an interview.
Numbers You Should Know
Learn the handful of numbers every estimate is built from: how big data is, how long common operations take, and how many seconds are in a day or a month.
Estimating QPS, Storage, and Bandwidth
Learn to estimate traffic, storage, and bandwidth from a user count, add the cache calculation, and work through the four of them in the right order.
A Worked Estimation Example
Follow a full estimation for a photo sharing service, from stated assumptions to traffic, storage, bandwidth, and cache, and see what each number decides.
Flashcards Review
Review the key ideas of back-of-the-envelope estimation with flashcards on the core numbers and the traffic, storage, bandwidth, and cache calculations.
Chapter Assessment
Test your understanding of back-of-the-envelope estimation: the core numbers, the four standard calculations, and how to state your assumptions.
4.
Network Essentials
7 lessons
HTTP vs. HTTPS
Understand how HTTP works, what HTTPS adds with TLS, how certificates stop man-in-the-middle attacks, and what encryption still does not hide.
TCP vs. UDP
Compare TCP and UDP, covering the three-way handshake, reliable ordered delivery, congestion control, head-of-line blocking, and when each one fits.
HTTP: 1.0 vs. 1.1 vs 2.0 vs. 3.0
Compare HTTP/1.0, 1.1, 2, and 3, covering persistent connections, multiplexing, header compression, head-of-line blocking, and QUIC over UDP.
URL vs. URI vs. URN
Understand how URIs, URLs, and URNs relate, the parts of a URL, absolute and relative forms, and what each one means for caching and stored identifiers.
What Happens When You Type a URL into the Browser
Follow one request end to end: URL parsing, DNS, the TCP and TLS handshakes, the CDN edge, the origin and its cache, and where the time goes.
Flashcards Review
Review the key ideas of network essentials with flashcards on HTTP versions, HTTPS and TLS, TCP and UDP, URLs, and the path of a single request.
Chapter Assessment
Test your understanding of network essentials: HTTP and HTTPS, TCP and UDP, the HTTP versions, URLs and URNs, and the path one request takes.
5.
Long-Polling vs. WebSockets vs. Server-Sent Events
7 lessons
Introduction to Real-Time Communication
Understand why a plain HTTP request cannot push updates, how polling fills the gap, and why polling stops scaling as users and update rates grow.
What is Long-Polling?
Understand how long-polling holds a request open until the server has data, what it costs in connections, and where this technique still fits.
What is WebSocket?
Understand how the WebSocket handshake turns one HTTP connection into a two-way channel, what it costs the server, and where WebSockets fit best.
What are Server-Sent Events?
Understand how Server-Sent Events stream one-way updates over a long-lived HTTP connection, their strengths and limits, and where they fit.
Difference Between Long-Polling, WebSockets, and Server-Sent Events
Compare long-polling, WebSockets, and Server-Sent Events side by side, learn how to choose between them, and how to explain that choice clearly.
Flashcards Review
Review the key ideas of real-time communication with flashcards on polling, long-polling, WebSockets, Server-Sent Events, and choosing between them.
Chapter Assessment
Test your understanding of real-time communication: why HTTP cannot push updates, polling, long-polling, WebSockets, and Server-Sent Events.
6.
Domain Name System (DNS)
5 lessons
Introduction to DNS
Understand what DNS does, how to read a domain name, the root, TLD, and authoritative levels, the common record types, and the kinds of resolvers.
DNS Resolution Process
Understand how a name resolves through recursive and iterative queries, how caching and TTL shape the answer, and how to change an IP address safely.
DNS Load Balancing and High Availability
Understand how DNS spreads load with round-robin, health-checked, weighted, and location-based answers, plus anycast routing and where it stops.
Flashcards Review
Review the key ideas of DNS with flashcards on the name hierarchy, record types, resolvers, recursive and iterative queries, caching, TTL, and anycast.
Chapter Assessment
Test your understanding of DNS: the name hierarchy, record types and TTL, recursive and iterative resolution, caching, and DNS load balancing.
7.
Proxies
5 lessons
What is a Proxy Server?
Understand what a proxy server does, how forward and reverse proxies differ, what each one hides, and which jobs each of them is used for.
Uses of Proxies
Learn the ten common jobs a proxy does, grouped into making traffic faster, making it safer, and keeping control of what passes through it.
VPN vs. Proxy Server
Compare a VPN and a proxy server on encryption, scope, and trust, learn the five differences between them, and know which one to reach for.
Flashcards Review
Review the key ideas of proxies with flashcards on forward and reverse proxies, caching, collapsed forwarding, the common uses, and VPNs.
Chapter Assessment
Test your understanding of proxies: forward and reverse proxies, what each one hides, caching, collapsed forwarding, the common uses, and VPNs.
8.
Load Balancing
10 lessons
Introduction to Load Balancing
Understand what a load balancer does, how it picks a server, plus health checks, session persistence, TLS termination, and where to place one.
Load Balancing Algorithms
Compare nine load balancing algorithms, from round robin and least connections to IP hash and least response time, and learn how to choose one.
Uses of Load Balancing
Learn the five main uses of load balancing: high availability, horizontal scaling, zero-downtime deployments, attack mitigation, and SSL termination.
Load Balancer Types
Compare the types of load balancer: hardware, software, cloud, DNS, global server load balancing, hybrid, and the Layer 4 and Layer 7 split.
Stateless vs. Stateful Load Balancing
Compare stateless and stateful load balancing, how each one treats a client session, and what each approach costs in memory and flexibility.
High Availability and Fault Tolerance
Learn how to stop a load balancer from becoming a single point of failure, using redundancy, failover strategies, health checks, and shared state.
Scalability and Performance
Learn how to scale load balancers horizontally and vertically, manage connection and request rate limits, and limit their effect on latency.
Challenges of Load Balancers
Learn the seven common problems with load balancers: single points of failure, configuration, scaling limits, latency, sticky sessions, and cost.
Flashcards Review
Review the key ideas of load balancing with flashcards on the algorithms, health checks, load balancer types, the OSI layers, and sticky sessions.
Chapter Assessment
Test your understanding of load balancing: where a balancer sits, the algorithms, the types and OSI layers, stateless routing, and failover.
9.
API Gateway
5 lessons
Introduction to API Gateway
Understand what an API gateway does, why systems use one, how a request flows through it, how it differs from a load balancer, and what it costs.
Usage of API gateway
Learn the twenty jobs an API gateway does, grouped into routing requests, reshaping them, protecting the backend, and running an API as a business.
Advantages and disadvantages of using API gateway
Weigh the advantages and disadvantages of an API gateway, read its latency cost honestly, and decide when one is worth adding to a system.
Flashcards Review
Review the key ideas of API gateways with flashcards on routing, authentication, rate limiting, request reshaping, and gateway versus load balancer.
Chapter Assessment
Test your understanding of API gateways: what one does, how a request flows through it, its common jobs, and how it differs from a load balancer.
10.
Rate Limiting and Throttling
6 lessons
What Is Rate Limiting
Understand what rate limiting caps, who counts as one client, how throttling relates to it, why systems need it, and what a limited client sees.
Rate Limiting Algorithms
Compare the token bucket, leaky bucket, fixed window, sliding window log, and sliding window counter, and see how each one handles a burst.
Distributed Rate Limiting
Understand why a limit multiplies across servers, how a shared counter fixes it, the race that lets extra requests through, and cheaper approximations.
Rate Limiting in Practice
Learn where the limiter should sit, what to tell a rejected client, how clients should retry, and how to choose the number behind a limit.
Flashcards Review
Review the key ideas of rate limiting with flashcards on the five counting algorithms, bursts, distributed counters, and what a rejected client sees.
Chapter Assessment
Test your understanding of rate limiting: what a limit is made of, the five algorithms and bursts, distributed counters, and what to tell a client.
11.
Caching
11 lessons
Introduction to Caching
Understand what a cache is, how hits and misses work, what eviction and staleness mean, where caches live in a system, and what caching costs.
Why is Caching Important?
Learn why caching matters: lower latency, better performance, less network load, higher scalability, and a smoother experience for users.
Types of Caching
Compare the types of caching, from in-memory, disk, and database caches to client-side, server-side, CDN, and DNS caching, and where each belongs.
Cache Replacement Policies
Compare the cache replacement policies that decide what to evict when a cache fills up: least recently used, least frequently used, FIFO, and random.
Cache Invalidation
Learn why invalidation matters, the write-through, write-around, write-back, and write-behind strategies, and methods like purge, ban, and TTL.
Cache Read Strategies
Compare the read-through and read-aside cache strategies, covering which component fetches data on a miss and what each one asks of your code.
Cache Coherence and Consistency Models
Understand cache coherence across many caches, and the consistency models that decide how quickly every copy of the data sees an update.
Caching Challenges
Learn the six common cache problems and their fixes: thundering herd, cache penetration, big keys, hot keys, cache pollution, and cache drift.
Cache Performance Metrics
Learn the metrics that show whether a cache is earning its place: hit rate, miss rate, cache size, and cache latency, and how to read them.
Flashcards Review
Review the key ideas of caching with flashcards on hits and misses, replacement policies, write strategies, invalidation, and the common problems.
Chapter Assessment
Test your understanding of caching: hits and misses, the caching types, replacement policies, write and read strategies, invalidation, and metrics.
12.
CDN
6 lessons
What is CDN?
Understand what a CDN is, how points of presence, edge servers, and the origin fit together, how a request is served, and what to put on a CDN.
Origin Server vs. Edge Server
Compare the origin server with an edge server, what each one stores and does, and how the two work together to serve a single request.
CDN Architecture
Understand where CDN servers sit, how anycast, DNS, and GeoIP routing find an edge server, how cached copies stay fresh, and the network topologies.
Push CDN vs. Pull CDN
Compare pull and push CDNs on who moves the content to the edge servers and when, and learn which model suits which kind of site.
Flashcards Review
Review the key ideas of CDNs with flashcards on points of presence, edge servers, the origin, request routing, TTL and purging, and push versus pull.
Chapter Assessment
Test your understanding of CDNs: points of presence and edge servers, how a request reaches the nearest edge, keeping copies fresh, and push versus pull.
13.
Data Partitioning
7 lessons
Introduction to Data Partitioning
Understand what data partitioning is, the terms behind it, and why splitting a large dataset into smaller independent partitions makes it manageable.
Partitioning Methods
Compare the three partitioning schemes, horizontal, vertical, and hybrid, and learn what each one splits and when large applications reach for it.
Data Sharding Techniques
Compare six sharding techniques: range-based, hash-based, directory-based, geographical, dynamic, and hybrid, and see why none of them is SQL-only.
Benefits of Data Partitioning
Learn the ten benefits of data partitioning, from faster queries and scalability to load balancing, parallel processing, and faster recovery.
Common Problems Associated with Data Partitioning
Learn the seven problems partitioning brings: complexity, data skew, key selection, cross-partition queries, migration, maintenance, and cost.
Flashcards Review
Review the key ideas of data partitioning with flashcards on horizontal and vertical splits, the sharding techniques, partition keys, and data skew.
Chapter Assessment
Test your understanding of data partitioning: the partitioning methods, the sharding techniques, choosing a key, data skew, and cross-partition queries.
14.
Redundancy and Replication
6 lessons
What is Redundancy?
Understand what redundancy is, how it removes a single point of failure, what it buys in reliability and recovery, and what it costs to run.
What is Replication?
Understand what database replication is, how it differs from redundancy, and compare synchronous, asynchronous, and semi-synchronous replication.
Replication Methods
Compare seven replication arrangements, from single-leader and multi-leader to leaderless quorums, chain, read-replica, snapshot, and hybrid.
Data Backup vs. Disaster Recovery
Understand why replication is not a backup, how data backup and disaster recovery differ, and how all three ideas fit together in one plan.
Flashcards Review
Review the key ideas of redundancy and replication with flashcards on single points of failure, the replication modes, leaders, and backups.
Chapter Assessment
Test your understanding of redundancy and replication: single points of failure, the replication modes and methods, and backup versus disaster recovery.
15.
CAP & PACELC Theorems
8 lessons
Introduction to CAP Theorem
Understand what the CAP theorem claims, where the choice is actually made, why partitions are not optional, and how familiar products reflect it.
Components of CAP Theorem
Understand consistency, availability, and partition tolerance in their strict technical sense, and why the C in CAP is not the C in ACID.
Trade-offs in CAP Theorem
Understand why no system gets all three guarantees, walk through the impossible case, and compare the CP, AP, and CA categories.
Examples of CAP Theorem in Practice
See how MongoDB, Cassandra, ZooKeeper, and DynamoDB land on either side of the CAP choice, and what each one does when the network splits.
Beyond CAP Theorem
Understand what CAP leaves out, how PACELC adds latency to the picture, and how CRDTs and per-operation choices soften the trade-off.
System Design Trade-offs in Interviews
Learn five moves for handling a consistency trade-off, from asking the deciding question to naming what the choice costs and offering a mixed approach.
Flashcards Review
Review the key ideas of CAP and PACELC with flashcards on the three properties, the CP and AP categories, real systems, and the latency trade-off.
Chapter Assessment
Test your understanding of CAP and PACELC: the three properties, why partitions are a given, the CP and AP categories, and real system examples.
16.
Databases (SQL vs. NoSQL)
12 lessons
Introduction to Databases
Understand what a database and a DBMS are, and the five differences between relational and non-relational systems that matter from the start.
SQL Databases
Understand how relational databases model data in tables with primary and foreign keys, what SQL does, the main engines, and where this model strains.
NoSQL Databases
Understand the six types of NoSQL database, the four you will be asked about, what you gain and give up, and when this model actually fits.
SQL vs. NoSQL
Compare SQL and NoSQL on data model and schema, scalability, consistency and transactions, query complexity, performance, and operational cost.
ACID vs BASE Properties
Understand the four ACID promises and the three BASE properties, why the C in ACID differs from the C in CAP, and how to choose between them.
Real-World Examples and Case Studies
See where SQL won, where NoSQL won, and where systems used both, and learn what the pattern across those choices tells you about your own.
SQL Normalization and Denormalization
Understand how normalization splits data to remove duplication, how denormalization brings it back for cheap reads, and the trade between them.
In-Memory Database vs. On-Disk Database
Compare in-memory and on-disk databases on speed, durability, and cost, and learn which kinds of workload belong in each one.
Data Replication vs. Data Mirroring
Compare data replication with data mirroring, learn the five differences between them, and see why many systems end up using both.
Database Federation
Understand how database federation presents several independent databases as one, how a federated query actually runs, and what it suits.
Flashcards Review
Review the key ideas of databases with flashcards on tables and keys, the NoSQL types, ACID and BASE, normalization, and federation.
Chapter Assessment
Test your understanding of databases: the relational model, the NoSQL types, SQL versus NoSQL, ACID and BASE, normalization, and federation.
17.
Indexes
7 lessons
What are Indexes?
Understand what an index stores, how it replaces a full table scan, why selectivity decides whether it helps, and what it costs in writes.
How a B-Tree Index Works
Understand the shape of a B-tree, why it stays three or four levels deep, how it serves point and range reads, and what an insert really costs.
Types of Indexes
Compare eleven index types, from primary, unique, and clustered to composite, covering, partial, bitmap, full-text, hash, and geospatial.
B-Tree vs. LSM Tree
Compare B-trees and LSM trees on updating in place versus appending, read cost, compaction, the three amplifications, and how to choose.
Indexes in Distributed Systems
Understand what sharding takes away, how local and global secondary indexes differ, what scatter-gather costs, and the traps in global indexes.
Flashcards Review
Review the key ideas of indexes with flashcards on selectivity and table scans, B-trees and LSM trees, the index types, and sharded indexes.
Chapter Assessment
Test your understanding of indexes: selectivity and table scans, how a B-tree stays shallow, page splits, the index types, and sharded indexes.
18.
Bloom Filters
6 lessons
Introduction to Bloom Filters
Understand how a bit array and several hash functions answer set membership, why a wrong no is impossible, and how to size a filter properly.
Benefits & Limitations of Bloom Filters
Weigh the five benefits of a Bloom filter, from tiny memory to constant-time checks, against the five limits, including false positives.
Variants and Extensions of Bloom Filters
Compare the Bloom filter variants, counting, compressed, spectral, scalable, and cuckoo, and learn what each one pays for the limit it removes.
Applications of Bloom Filters
See the five main uses of Bloom filters, from skipping disk reads to spam checks, and learn the single pattern behind all of them.
Flashcards Review
Review the key ideas of Bloom filters with flashcards on bit arrays and hash functions, false positives, sizing, the variants, and the uses.
Chapter Assessment
Test your understanding of Bloom filters: bit arrays and hash functions, false positives versus false negatives, sizing, and the variants.
19.
Quorum
4 lessons
Why Quorum?
Understand why systems keep replicas, the new problem replication creates when copies disagree, and what a system needs to settle on one answer.
What is Quorum?
Understand how a quorum settles an operation, how to size it, why an odd node count helps, the R + W > N rule, and how to tune it to a workload.
Flashcards Review
Review the key ideas of quorum with flashcards on replicas, quorum size, odd node counts, the R + W > N rule, and tuning reads and writes.
Chapter Assessment
Test your understanding of quorum: why replicas disagree, quorum size, odd node counts, the R + W > N rule, and tuning reads and writes.
20.
Leader and Follower
3 lessons
What is Leader and Follower Pattern?
Understand how one leader coordinates its followers, what happens when the leader fails, and the strengths, weaknesses, and uses of the pattern.
Flashcards Review
Review the leader and follower pattern with flashcards on the leader's job, replication to followers, failover and elections, and the pattern's limits.
Chapter Assessment
Test your understanding of the leader and follower pattern: the leader's job, replication to followers, failover, and where the pattern falls short.
21.
Heartbeat
3 lessons
What is Heartbeat?
Understand how heartbeat messages detect a failed server, how to pick the interval and the timeout, and why one missed beat is not proof of failure.
Flashcards Review
Review the key ideas of heartbeats with flashcards on failure detection, the timeout rule, picking an interval, and false suspicion of a server.
Chapter Assessment
Test your understanding of heartbeats: why failure detection matters, the timeout rule, picking the interval, and why a missed beat is not proof.
22.
Checksum
4 lessons
What is Checksum?
Understand what a checksum is, how it is computed and verified, how it catches a single flipped bit, and what it cannot protect against.
Uses of Checksum
See where checksums are used, from network transfers and disk corruption to comparing replicas and verifying downloads, and where they do not fit.
Flashcards Review
Review the key ideas of checksums with flashcards on hash functions, verification, detecting corruption, comparing replicas, and the limits.
Chapter Assessment
Test your understanding of checksums: how one is computed and verified, what it detects, where it is used, and what it cannot protect against.
23.
Distributed Messaging System
8 lessons
Introduction to Messaging System
Understand why services stop talking directly, what a messaging system is, the queue and publish-subscribe models, and what a broker does.
Introduction to Kafka
Understand Kafka as a distributed commit log: its common terms, its high-level architecture, its use cases, and how the cluster tracks its own state.
Messaging patterns
Compare the five messaging patterns: point-to-point, publish-subscribe, request-reply, fan-out and fan-in, and the dead letter queue.
Popular Messaging Queue Systems
Meet the four messaging systems you will face most often, RabbitMQ, Kafka, Amazon SQS, and ActiveMQ, and learn how to think about the options.
RabbitMQ vs. Kafka vs. ActiveMQ
Compare RabbitMQ, Kafka, and ActiveMQ on the ideas they are built on, their key differences, and how to choose one of them for a system.
Scalability and Performance
Learn how a messaging system scales, through partitioning, consumer groups, parallel processing, and message batching and compression.
Flashcards Review
Review the key ideas of distributed messaging with flashcards on brokers, queues and publish-subscribe, the patterns, Kafka terms, and partitions.
Chapter Assessment
Test your understanding of distributed messaging: brokers, queues and publish-subscribe, the five patterns, Kafka, and scaling consumers.
24.
Distributed File Systems
5 lessons
What is a Distributed File System?
Understand how a distributed file system spreads files across machines while showing one folder tree, plus its common uses and its challenges.
Architecture of a Distributed File System
Understand how a read travels through a distributed file system, why metadata is kept apart from file data, and how HDFS puts it together.
Key Components of a DFS
Understand the three properties that shape a distributed file system: how it replicates blocks, how it scales, and what consistency it offers.
Flashcards Review
Review the key ideas of distributed file systems with flashcards on metadata servers, storage nodes, blocks, replication, and consistency.
Chapter Assessment
Test your understanding of distributed file systems: metadata servers and storage nodes, how a read travels, blocks, replication, and consistency.
25.
Security
9 lessons
What is Security and Privacy?
Understand how security and privacy differ, why distributed systems are harder to protect, and the defenses this chapter covers in detail.
What is Authentication?
Understand how authentication proves identity, the three kinds of proof, how a login works, and the common authentication methods and types.
What is Authorization?
Understand how authorization decides what an identified user may do, how roles and permissions work, and how a permission check runs.
Authentication vs. Authorization
Compare authentication and authorization, see the key differences in one example, and learn why the two gates are so easy to mix up.
OAuth vs. JWT for Authentication
Understand what OAuth grants and what a JWT carries, the key differences between a protocol and a token format, and how the two fit together.
What is Encryption?
Understand how encryption scrambles data, how symmetric and asymmetric keys differ, where encryption is used, and the challenges it brings.
What are DDoS Attacks?
Understand how a DDoS attack floods a service with fake traffic, the common types of attack, and the strategies that mitigate them.
Flashcards Review
Review the key ideas of security with flashcards on authentication and authorization, OAuth and JWT, encryption keys, and DDoS mitigation.
Chapter Assessment
Test your understanding of security: authentication and authorization, OAuth and JWT, symmetric and asymmetric encryption, and DDoS attacks.
26.
Misc Concepts
10 lessons
Batch Processing vs. Stream Processing
Compare batch and stream processing on when each one handles data, their key differences, and how to pick one for a given workload.
XML vs. JSON
Compare XML and JSON as data exchange formats, covering syntax, size, and readability, and learn which one suits which kind of interface.
Synchronous vs. Asynchronous Communication
Compare synchronous and asynchronous communication, what waiting for an answer costs a system, and how to decide for each hop in a request.
Push vs. Pull Notification Systems
Compare push and pull notification systems on who starts the conversation, the delay a user sees, and the load each model puts on servers.
Microservices vs. Serverless Architecture
Compare microservices and serverless architecture on who runs the code, how each one scales and is billed, and when each model is the better fit.
Message Queues vs. Service Bus
Compare a message queue with a service bus, see what a bus adds beyond carrying messages, and learn which middle piece a system needs.
Stateful vs. Stateless Architecture
Compare stateful and stateless architecture, see where the state goes once servers stop holding it, and learn what each choice costs.
Event-Driven vs. Polling Architecture
Compare event-driven and polling architecture on how one part learns that something changed, the delay each adds, and what each one costs.
Flashcards Review
Review this chapter with flashcards on all eight comparisons, from batch and stream processing to event-driven and polling architecture.
Chapter Assessment
Test your understanding of the eight comparisons: batch and stream, XML and JSON, sync and async, push and pull, and stateful and stateless.
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About the Author
Arslan Ahmad
Design Gurus Founder
Ex-FAANG Manager
Meta
Microsoft
Google
Amazon
Uber
Industry Expertise & Leadership
Arslan Ahmad is the lead author of System Design Fundamentals. As the founder of Design Gurus and a former FAANG hiring manager, he has worked at industry giants like Facebook (now Meta) and Microsoft.
He has conducted hundreds of system design interviews, giving him unique insight into what top tech companies look for in candidates.
The course also incorporates expertise from senior engineers at Google, Meta, Amazon, Microsoft, and Uber, ensuring you learn system design best practices from professionals who have built and scaled real-world systems.
500+
Interviews Conducted
10k+
Students Taught
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FAQs
What are the fundamentals of system design?
They are the building blocks every large system is made from and the ideas behind them: scalability, availability, and latency; load balancing, caching, CDNs, and proxies; data partitioning, replication, indexes, and SQL and NoSQL databases; the CAP theorem; messaging and queues; and distributed patterns like quorum, heartbeat, and leader and follower. This course teaches each one in its own chapter, in the order you need them.
Are there any prerequisites for System Design Fundamentals?
No, there are no strict prerequisites; this course is designed to be beginner-friendly. It starts with the basics of system design, so as long as you have basic programming knowledge, you can easily follow along and learn system design fundamentals from scratch.
Can I take this course with no distributed systems experience?
Yes. Every part is described in plain words before its technical name appears, and each chapter explains what problem the part solves and what new problem it creates, so you do not need to have run a large system to follow along.
Which topics does the course cover?
The key characteristics of distributed systems, back-of-the-envelope estimation, network essentials, real-time delivery with long-polling, WebSockets, and server-sent events, DNS, proxies, load balancing, API gateways, rate limiting, caching, CDNs, data partitioning, redundancy and replication, the CAP and PACELC theorems, SQL and NoSQL databases, indexes, Bloom filters, quorum, leader and follower, heartbeat, checksum, distributed messaging with Kafka, distributed file systems, and security.
Do I need to know how to code to learn system design?
Basic programming knowledge is enough. The lessons contain no coding exercises; they explain how the parts of a system work and when to use them, with diagrams, flashcards, and quizzes rather than code.
Is this course text-based or video-based?
The course content is delivered entirely through text-based lessons (no video lectures). This format lets you read and learn at your own pace, with clear explanations and diagrams throughout to help you understand each concept.
How long does it take to complete this fundamentals course?
The course has about 20 hours of content, but since it is self-paced, you can take as long as you need to finish. Many learners complete it in a few weeks by studying a bit each day, while others spread it out over a couple of months; the timing is completely up to you.
Does this course include quizzes or practice exercises?
Yes. Every chapter ends with a flashcards review and an adaptive chapter assessment, and the course finishes with a final quiz drawn from a question bank covering every chapter, so you can test yourself on each topic before moving on.
Will System Design Fundamentals help me prepare for system design interviews?
Absolutely, this course builds the foundation that system design interviews test: load balancing, caching, data partitioning, replication, and the CAP theorem, plus interview skills like back-of-the-envelope estimation. Once you finish, Grokking the System Design Interview is the recommended next step.
Should I take this course or Grokking the System Design Interview first?
Take this course first if you cannot yet explain what a load balancer, a cache, a replica, and a message queue each do. If you can, and your interview is close, start with Grokking the System Design Interview and come back to a chapter here whenever a building block feels unclear.
Is there a free way to start?
Yes. You can read the opening lessons of the course free before you buy, and the free five-day email mini course on system design interviews covers the key principles, scalability and availability, and the system design master template.
Is this the same course as Grokking System Design Fundamentals?
Yes. We renamed the course to System Design Fundamentals; the content and your progress are unchanged.
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