Learn
37 short lessons on the layer nobody grades you on — how the things you studied actually behave in production, and what has changed since you graduated. Written for engineering graduates and early-career backend developers.
Each one is a five-to-twelve minute read with a concrete exercise at the end. Read them in order or jump to what you need. If you want to track progress, the brush-up tracker ticks off the same lessons.
Fundamentals, the production version
You learned these for exams — this is where they actually bite
Big-O where it actually bites
7 min · 23 JulNot proving bounds — spotting the accidental O(n²) before it reaches real data.
Concurrency, for real
9 min · 23 JulRace conditions, deadlocks, optimistic locking, and how an event loop differs from threads.
Memory in a managed runtime
8 min · 24 JulHow GC behaves in Node/JVM/Python, and what a genuine leak looks like.
Networking past the OSI chart
8 min · 26 JulTLS handshakes, connection pooling, keep-alive, and why p99 is a different story from p50.
Databases, past the CRUD layer
You know SQL — these are the parts that separate junior from senior
Indexing strategy
9 min · 26 JulWhen an index helps, when it taxes every write, and why composite column order matters.
Transactions and isolation levels
9 min · 27 JulRead committed vs repeatable read vs serializable — which anomalies each still allows.
Query plans and N+1
9 min · 28 JulRead EXPLAIN well enough to catch the pattern in review, not in an incident.
SQL vs NoSQL, the honest version
8 min · 28 JulNot "NoSQL is faster" — the real trade-offs for a specific access pattern.
Caching and invalidation
9 min · 29 JulCache-aside vs write-through, TTL choices, and deciding how stale is acceptable.
System design
The gap between "I built a CRUD app" and "I can design a system"
The two warm-up designs
11 min · 29 JulA URL shortener and a rate limiter, on paper, before reading anyone else’s answer.
CAP, applied
8 min · 31 JulWhich side you would pick for a specific product, and what you tell users when it degrades.
Load balancing and horizontal scale
10 min · 31 JulSharding, replication, stateless services, and how one scaling decision forces the next.
Queues and async processing
10 min · 1 AugWhen decoupling is worth it, at-least-once vs exactly-once, and idempotent consumers.
Reading real engineering writeups
6 min · 1 AugReal constraints and real regrets, not toy diagrams.
APIs, auth and backend architecture
Solidify the layer you touch every day
REST vs RPC vs GraphQL
8 min · 2 AugWhen each genuinely fits, beyond syntax preference.
OAuth 2.1, JWT and PKCE
11 min · 3 AugExplain the full authorization-code flow out loud, without notes.
Versioning and backward compatibility
8 min · 3 AugChange an API without breaking clients you cannot deploy or contact.
Rate limiting and idempotency
9 min · 5 AugToken buckets, idempotency keys, and retries that are safe to repeat.
Timeouts, retries and circuit breakers
9 min · 6 AugExponential backoff with jitter, circuit breakers, and errors a client can act on.
Infrastructure and deployment
What is standard now, not what was standard when you started college
Containers, properly
9 min · 7 AugNamespaces, cgroups and layers — what Docker actually does, not just the CLI.
CI/CD as the default
8 min · 7 AugAutomated tests and deploys as baseline, with a rollback you have actually tested.
Observability
10 min · 8 AugLogs, metrics and traces — debugging production without adding print statements.
Serverless vs containers vs VMs
8 min · 10 AugCold starts, cost curves and operational load — when each is genuinely right.
Infrastructure as code
8 min · 10 AugClicking through a cloud console does not survive a second environment.
Security
Usually skipped in college, assumed in every real job
The OWASP Top 10, by shape
12 min · 11 AugInjection, XSS, CSRF, broken access control — know the shape of each, not the name.
Encryption basics
9 min · 12 AugSymmetric vs asymmetric, hashing vs encryption, and how a TLS certificate earns trust.
Secrets management
8 min · 13 AugWhy a .env in git is a breach waiting to happen, and what a vault plus rotation solves.
Least privilege
8 min · 13 AugDesign so one leaked token cannot do everything. Scope it, expire it, audit it.
Staying current
The habit that stops the brush-up from going stale again
One engineering blog post a week
5 min · 15 AugProduction lessons, not tutorials.
Follow what ships in your stack
5 min · 16 AugKnow what changed in your language and framework, and why they changed it.
Read one open-source codebase
7 min · 16 AugStudy the structure and the taste, not just the API.
Explain something out loud monthly
5 min · 17 AugGaps surface within about two minutes of talking.
Prove it — practice ladder
This sticks when you build, not when you read
Rebuild one old project properly
7 min · 18 AugSame idea, production standards — tests, real auth, a real database, deployed.
Ship an API with auth and a real database
9 min · 20 AugThe whole loop end to end, running somewhere other than your laptop.
Add a queue to something
8 min · 21 AugProducer, consumer, retries, dead-letter queue — then kill the consumer mid-job.
Dockerize and automate an existing project
8 min · 22 AugCompose file, tests in CI, deploy on merge.
Load-test it and fix the bottleneck
9 min · 22 AugFind the first thing that breaks under load, fix it, measure again.