Data Structures Toolkit
How the structures underneath every algorithm actually work — arrays, hash tables, trees, and more, visualized step by step. All run entirely in your browser.
How these fit together
Hash Table Visualizer runs a real hash table with separate chaining — insert or look up a key and watch it hashed character by character, folded down onto a bucket index, and either slotted in cleanly or appended to a chain when it collides with something already there. It's the mechanism behind the "O(1) average" quoted for hash maps and sets throughout the Algorithms Toolkit, made concrete instead of taken on faith.