AlgorithmsGraphs and textRuns in your browserReviewed October 1, 2026

Memoization Visualizer

Cache the result of a function call so repeated calls are instant. Interactive step-by-step animation with JavaScript code, complexity and front-end use cases.

Localprivate by defaultFastno sign-up path

Graphs and textTime: O(n) instead of O(2ⁿ) for FibonacciSpace: O(n)

fib(n)Memoization

fib(5)

Function calls

Memo cache

empty

Step 1 / 20

Recursive fib recomputes the same values again and again. Memoization stores each result so it is calculated once.

JavaScript

1function fib(n, memo = {}) {
2  if (n < 2) return n;
3  if (memo[n] !== undefined) return memo[n];
4  memo[n] = fib(n - 1, memo) + fib(n - 2, memo);
5  return memo[n];
6}

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

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Memoization Visualization and Animation

Cache the result of a function call so repeated calls are instant. Before computing, check whether the result is already in the cache. If it is, return it immediately. Otherwise compute it, store it and return it. Time complexity: O(n) instead of O(2ⁿ) for Fibonacci. Space complexity: O(n). useMemo, reselect, expensive derived values and any pure function called with the same input repeatedly.

How to use Memoization Visualizer

Before computing, check whether the result is already in the cache.
If it is, return it immediately.
Otherwise compute it, store it and return it.
Press Play, or step through with the arrow buttons and change the input to see how it reacts.

Questions

What is Memoization?

Cache the result of a function call so repeated calls are instant.

What is the time complexity of Memoization?

Time: O(n) instead of O(2ⁿ) for Fibonacci. Space: O(n).

Where do front-end developers use Memoization?

useMemo, reselect, expensive derived values and any pure function called with the same input repeatedly.

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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