Cheat Sheet

Dense 5–15 minute refreshers. Not another lesson track — just the syntax and interview points you already know.

Backend

Queries, aggregation pipelines and data modelling

Event loop, streams, async patterns and performance

Joins, window functions and query planning

Data structures, caching strategies and expiry

Topics, partitions, consumer groups and delivery guarantees

Images, layers, networking and compose

Core services, IAM and deployment patterns

Data structures, algorithms and complexity

OOP, SOLID and design patterns applied

Scaling, storage choices and trade-offs