AlgoScope is a visual lab for algorithms
382 data structure and algorithm topics over 102 lessons, each one a run you step through rather than an animation you watch. Watch. Predict. Understand.
- 382topics in the curriculum
- 102lessons
- 666worked runs
- 3,900questions it asks you
The picture is the algorithm running
Every frame on this site comes from the engine executing the algorithm and recording what changed: 7,915 steps across 666 runs, exported at build time. Nothing is drawn by hand and nothing is a video. That is why the picture, the highlighted code line and the variables can never disagree with each other - they are three views of the same step, and the step is the thing that actually happened.
It stops and asks
At 3,900 points across the curriculum the player freezes before a decision and asks what happens next. You answer, then you see. Watching an algorithm is easy to mistake for understanding it; being asked to call the next comparison, and getting it wrong, is not.
One engine, three apps
The same engine runs in your browser, in the iOS app and in the Android app. None of the three implements an algorithm: they render the same recorded run, so a lesson behaves identically wherever you open it. The browser version compiles that engine to WebAssembly, which is what lets a lesson run on input you type in rather than only on the examples that ship.
What it costs
Every lesson here is free to open and needs no account, and there are no ads. An account remembers where you stopped and what you answered, across devices. Writing your own implementation and running it against a lesson's cases is free as well. The paid tier the home page describes - your own code driving the visualization step by step, a diff against the reference run, a readiness score - is not released yet, and nothing on this site charges for anything today.
What it is not
It is not a reference encyclopedia: 382 topics is a curriculum, not everything that exists. It is not a course with deadlines, grades or a certificate. And it does not write code for you - the point is the opposite, which is why the player asks before it tells.
Getting in touch
Mistakes in a lesson are worth reporting and get fixed: contact has the address and what to put in the report. If you are looking for where to start, the tracks are an ordered path through the curriculum rather than 29 categories to choose between.