Interview Prep
The questions interviews actually ask
The 1200 most-asked questions across 12 topics, ranked by how often each one comes up in real interviews, from startups to big tech. Every question has an interactive solution you can watch run, and every topic has lessons that teach it from scratch.
How to use it: learn the pattern, solve the #1–#30 questions in each topic first (they're the most common), and say your thinking out loud.
Core Algorithms
Arrays, strings, hash maps, two pointers, sliding windows, stacks, binary search and linked lists: the coding rounds at almost every company.
Trees, Graphs & DP
Trees, heaps, tries, graphs, backtracking and dynamic programming: what separates a pass from a strong pass at big tech.
JavaScript
Closures, this, promises, the event loop, and the utility functions front-end and full-stack interviews ask you to build by hand.
Python
Mutability, comprehensions, generators, decorators, classes and the standard library: what Python-heavy teams test.
Java
equals and hashCode, collections internals, strings, exceptions, generics, streams, concurrency, the JVM and modern Java: what Java and Spring teams test.
SQL & Databases
Joins, GROUP BY, subqueries, CTEs and window functions, run on real tables in your browser. Asked for back-end, data and full-stack roles.
Web & Frontend
HTML, CSS layout, the DOM, HTTP, browsers, React, security and accessibility: front-end and full-stack interview staples.
React Native
Components and styling, the new architecture, hooks, list performance, navigation, native modules, storage, animations, testing and shipping to the app stores.
System Design
Scaling, caching, databases, queues and the classic "design X" questions, each with a diagram you can step through.
CS Fundamentals
Big-O, memory, processes and threads, operating systems, networking, databases, security and OOP: the theory rounds.
Git, Tools & AI
Git, debugging, testing, the command line, Docker, CI/CD and working with AI: what proves you can work on a real team.
Behavioral
Tell me about yourself, conflict, failure, leadership: build real stories with STAR and rehearse them against a timer.