AlgorithmsData structuresRuns in your browserReviewed October 1, 2026

Trie Autocomplete Visualizer

Store words letter by letter so every word with a given prefix can be found quickly. Interactive step-by-step animation with JavaScript code, complexity and front-end use cases.

Localprivate by defaultFastno sign-up path

Data structuresTime: O(prefix length + results)Space: O(total letters)

Words in the dictionaryUser typed (prefix)

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Step 1 / 14

A trie stores words letter by letter, so words that share a prefix share a path. A star (*) marks the end of a word.

JavaScript

1class Trie {
2  constructor() { this.root = { children: {}, end: false }; }
3  insert(word) {
4    let node = this.root;
5    for (const ch of word) {
6      node = node.children[ch] ??= { children: {}, end: false };
7    }
8    node.end = true;
9  }
10  suggest(prefix) {
11    let node = this.root;
12    for (const ch of prefix) {
13      node = node.children[ch];
14      if (!node) return [];
15    }
16    return collect(node, prefix); // every node with end: true is a word
17  }
18}

Tip: use the arrow keys to step and the space bar to play or pause.

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Trie Autocomplete Visualization and Animation

Store words letter by letter so every word with a given prefix can be found quickly. Insert each word letter by letter, reusing existing nodes. Follow the typed prefix down the tree. Collect every word below that node as suggestions. Time complexity: O(prefix length + results). Space complexity: O(total letters). Search suggestions, command palettes, tag inputs and spell checkers.

How to use Trie Autocomplete Visualizer

Insert each word letter by letter, reusing existing nodes.
Follow the typed prefix down the tree.
Collect every word below that node as suggestions.
Press Play, or step through with the arrow buttons and change the input to see how it reacts.

Questions

What is Trie Autocomplete?

Store words letter by letter so every word with a given prefix can be found quickly.

What is the time complexity of Trie Autocomplete?

Time: O(prefix length + results). Space: O(total letters).

Where do front-end developers use Trie Autocomplete?

Search suggestions, command palettes, tag inputs and spell checkers.

Does this upload my data?

No. This converter runs in your browser for ordinary use, so the input is not sent to a backend by this tool.

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