Make the invisible click.
A backend engineer’s library for learning backend engineering and system design - from what a server actually is, to the first request, to the last deployed container.
Backend engineering topics, mapped
We skip the jargon. Let’s form better technical instincts together.
Backend fundamentals, before the deep dives
The plain-English basics that most tutorials assume you already know - what a server actually is, how a request becomes a response, and who is responsible for what.
14 lessons liveLanguage runtimes and execution mechanics
A plain-English look at how popular backend languages run your code, share work, and use memory.
8 lessons liveProtocols, APIs, and networking
How a request travels between a user and your backend, from a web address to a response.
10 lessons liveData structures and algorithms, in context
The data structures and algorithms real backend systems run on, each explained by the specific problem it solves.
10 lessons liveData storage, distributed systems, cloud infrastructure, and production engineering are being written next.
How real systems are built
Case studies from companies that actually run this stuff.
Designing for failure instead of hoping it won't happen
A dispatch problem that's really a real-time geospatial problem
Millions of concurrent WebSocket connections, and the language choices that followed
Money can't be 'probably correct' - reliability as the actual product
Breaking apart a Ruby on Rails monolith without breaking the business
Hundreds of autonomous services, and the cloud migration that took years
Because a mental model is worth a thousand lines of log files.
Traditional computer science resources are either too abstractly academic or too hyper-focused on syntax. Backend Engineer bridges that gap for backend engineers and backend developers of every level, using clean, interactive illustrations that explain the invisible mechanics of scalable computing, system design, and cloud architecture.
Visual First
We map the invisible data flows, cache states, and network routing visually so they click instantly.
Deep but Readable
Written for engineers who want to understand the 'why' behind infrastructure decisions without reading research papers.
Always Free
High-quality, independent engineering education should be open to all developers, everywhere.
A workspace, not just a reading list.
54 questions
Interview Prep
Real interview questions, leveled for SDE1, SDE2, and SDE3+/Senior - each one tied to the full lesson behind it, not a generic list.
Interactive
System Design Canvas
Drag components onto a canvas, wire them into a system, and run a load simulation that shows exactly where it breaks - and why.
3 projects
Build It
A rate limiter, a URL shortener, a real-time chat server - each with a real implementation guide, not just a spec.
36 terms
Glossary
Backend terms defined in plain English - idempotency, backpressure, p99 latency - each linked back to the full lesson.
18 categories
AWS vs GCP vs Azure
Cloud services mapped by what they actually do, organized by category instead of vendor marketing names.
12 explainers
Deep Dives
How VPNs, cloud gaming, BitTorrent, and video streaming actually work - standalone explainers, same no-fluff style as everything else here.
Built by one backend engineer, for the backend engineer he used to be.
Most backend resources are either academic papers or shallow tutorials that skip the “why.” This site starts from the parts nobody explains - what a server actually is, why HTTP forgets you - and builds up to real system design, visually.
No paywall, on any of it. 42 lessons live across four phases - fundamentals, runtimes, protocols and APIs, and data structures in backend context - with data storage and distributed systems being written next.
Questions people usually ask first.
Is Backend Engineer actually free?
Yes, all of it - no paywall, no signup wall.
Do I need prior backend experience to start?
No. Phase 0 covers the fundamentals most tutorials skip.
Who is this actually for?
Junior-to-mid engineers, interview prep, and curious full-stack devs.
How much of the curriculum is live right now?
42 lessons across four phases - fundamentals, runtimes, protocols and APIs, and data structures in backend context.
Is it just lessons, or is there anything hands-on?
An interactive system design canvas, three build-it-yourself projects, real company architecture case studies, and role-leveled interview questions.
Still have a question? [email protected]
Start here
Three lessons to begin with.
Phase 0 · Backend fundamentals, before the deep dives
What is a server, really?
A server is just a program. See what a process, a port, and a socket actually are underneath the word 'server'.
Phase 1 · Language runtimes and execution mechanics
Node.js event loop
See how Node.js keeps handling work without waiting for every slow task to finish.
Phase 3 · Data structures and algorithms, in context
LRU caches: a hash map and a doubly linked list, working together
Why "evict the least recently used item" needs two data structures at once, and how that combination keeps both lookup and eviction O(1).
Get monthly visual system design breakdowns.
No spam, no fluff. Just a single monthly digest focusing on real-world backend engineering concepts and mental models.
One email a month, easy to unsubscribe from. Sent from [email protected].