10-20 minutes a day
Algorithms, AI Coding and System Design in short daily rounds. Solve by reasoning, tracing and tapping on diagrams rather than typing code, then go head to head with someone else on the same questions and the same clock.
Or start in your browser: pick a course or battle a rival. One account, one streak, on both.
Quick Play
Daily review
Data structures and algorithms as the patterns behind the problems. Trace the code, name the pattern, put the solution in order, find the bug.
6 courses
Plus company practice tracks, Quick Play and Battle.
Working with AI as an engineer. What it is and isn't, when to trust an answer and how to check it, tool calls and permissions, reading AI-written code, writing a good task, prompt injection and safe use.
8 courses
Claude Code in Practice and Agent Harnesses in Practice are tool guides.
Frame the requirements, size the load with small numbers, choose the parts, defend the tradeoff. Lessons draw the system: animated request flows, failures and scaling on component diagrams you tap.
4 courses
The case studies: a social feed, chat, a payments ledger, a video platform, a search engine.
Learn builds the pattern. Battle proves you have it.
Structured courses, at your pace.
Head to head, under a clock.
Open Today's Practice and get 10–20 short exercises from the subjects you picked, with feedback after every answer. You can finish a session over lunch, on the train, or before bed.
A Quick Play questionIs ([)] valid? Pick from four answers, then see why the tempting choice is wrong.
Multiple choiceTraceShort answer
Company tracks drill the patterns and questions those interviews are known for. They are part of AlgoFox Pro, on the web and in the app.
Inside the company tracksTake apart Trapping Rain Water, Number of Islands, and Koko Eating Bananas before rebuilding the optimal approach.
AmazonGoogleMeta
Wrong answers return in later sessions instead of disappearing into a completion score. Each subject keeps its own map of where to spend the next ten minutes.
The six Algorithms review categoriesTrack your progress across Arrays & Strings, Linear Structures, Trees, Graphs, Heaps & Intervals, and DP & Backtracking.
Mistake reviewPattern mapReview
Space complexity
Unit 1Capstone
By patternReview
I used to save interview prep for the weekend, then skip it. Ten minutes after lunch is a much lower bar, and I have finally stopped restarting from zero every few weeks.
The code tracing drills exposed something I had been hiding with pattern memorization. I could name DFS, but I could not always tell you what the stack was doing.
Mistake review is the part I keep coming back to. It does not let a lucky guess quietly count as understanding.
Start practising in your browser right now, for nothing. AlgoFox is on the App Store and on Google Play when you want it in your pocket too.
TraceDebugApproach
