Every compare lifts. Every swap arcs. Every finished element locks green. AlgoLens animates the meaning of each step — so you can watch with the sound off and still understand exactly what the algorithm did.
live · the actual AlgoLens engine sorting a random array on loop — amber compares, red swaps, green settles
One motion vocabulary, shared by every algorithm on the platform. A compare looks the same in bubble sort as it does in a binary search tree — so once you can read it, you can read everything.
The two elements under inspection lift and pulse amber — identical in bubble sort and in a BST search.
Out-of-order elements arc past each other. Nothing ever teleports; motion carries the meaning.
A finalized element drops into place with a spring bounce and locks green. Finality feels final.
Graph exploration spreads as a ripple from the source — BFS and DFS become distinguishable by shape alone.
A dead end flashes red with a quick shake — visually “no, not this one” — then fades back to neutral.
Every algorithm is a pure generator that yields state snapshots. The engine is a tape player: it can pause, scrub backwards, and replay any moment — because the steps are values, not side effects. That is also why the whole visualizer works offline and why a new algorithm is one new file.
// one file. no engine changes. no UI changes.
export const yourAlgorithm = {
id: "your-algorithm",
category: "sorting",
*generateSteps(input) {
yield {
description: "Compare a[0] with a[1]",
state: { kind: "array", ... },
};
},
};19 algorithms, all live, all watchable end to end.
63 original interview problems across the classic patterns — arrays, graphs, trees, DP, and more. Write real JavaScript or Python, graded instantly: JS runs in your browser, Python runs in an isolated sandbox with no network access. Nothing leaves your machine either way.
Start practicing✓ two_sum([2,7,11,15], 9)
✓ two_sum([3,2,4], 6)
✓ two_sum([3,3], 6)
✓ two_sum([-1,-2,-3,-4,-5], -8)
All 4 tests passedNo tutorials to copy — only project briefs to fulfill, staged Shu-Ha-Ri: follow the form, break it, then leave it behind. First path: Backend Engineering.
Begin the walk