Backend Engineer

Learn Go: the language behind Docker, Kubernetes, and most of modern infrastructure. Static types, fast compiles, no class hierarchies. Every lesson is hands-on with real go run execution.

Level up from Go Fundamentals. Interfaces, error handling patterns, goroutines, channels, select, defer/panic/recover. The features that make Go unique — and how real Go services use them.

Beyond Go Intermediate. Context cancellation, sync primitives in depth, generics (1.18+), reflection, unsafe. The features Go services running at scale actually use.

Learn SQL: the language for talking to databases. Used by literally every backend that stores anything. SELECT, JOIN, GROUP BY, aggregates, subqueries — once you have these you can answer any question your data can answer.

Level up from SQL Fundamentals. Subqueries, CTEs, window functions, set operations, transactions, indexes. The SQL features serious analytics and reporting use every day.

Build a fully functional Redis clone from the ground up. You'll implement the RESP protocol, key-value storage, expiry, lists, hashes, sets, sorted sets, and transactions — all through test-driven exercises. By the end, you'll deeply understand how one of the world's most popular databases works internally.

Build a production-grade key-value store from scratch. You'll start with an in-memory hash map, add ordered iteration and TTL, persist with write-ahead logging, build sorted SSTables, implement the LSM tree read path with compaction and Bloom filters, and add ACID transactions with MVCC snapshot isolation. By the end you'll deeply understand LevelDB, RocksDB, Cassandra, etcd, and FoundationDB.

Build a fully functional HTTP/1.1 server from raw TCP up. You'll parse requests, build responses, route paths, serve static files, handle keep-alive connections, manage worker concurrency, and produce real Common Log Format access logs. By the end you'll deeply understand what nginx, Apache, Caddy, and net/http actually do.

Build production-grade rate limiters: fixed window, sliding window, token bucket, leaky bucket. Then make them distributed (via Redis) and tiered (per-IP, per-user, per-plan). Used by every API gateway, web server, and microservice.

Build a production-grade L7 load balancer from scratch. You'll implement round-robin, weighted, and least-connection selection; active and passive health checks; circuit breakers; consistent hashing; sticky sessions; rate limiting; TLS termination (SNI); and Prometheus metrics. By the end you'll deeply understand what NGINX, HAProxy, Envoy, and AWS ALB actually do.

Build the registry behind Consul, Eureka, and Kubernetes service discovery: registration with TTLs, tags + metadata, health checks, load-balanced lookup, replicated HA, and the Kubernetes/service-mesh patterns. Used by every microservice architecture.

Implement JWT (JSON Web Tokens) end-to-end: base64url encoding, signing with HS256/RS256, claim validation, key rotation via kid, and defenses against the well-known JWT attacks (alg=none, key confusion, weak secrets). Used by every modern auth system.

Implement an OAuth 2.0 authorization server: authorization code flow, PKCE for public clients, access + refresh tokens with rotation, scopes, redirect URI validation, state-based CSRF defense, and token introspection. The auth protocol behind 'Login with Google/GitHub/Facebook' and every B2B SaaS.