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Insertion Sort Visualizer — Animated, Step-by-Step

Animated insertion sort with step controls, speed, custom input, live comparison/write counters and pseudocode. Runs in your browser.

Free No signup Client-side Privacy friendly Updated
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Comparisons: Swaps / writes: Array accesses:

Code examples

Ready-to-copy reference implementations. Free to use in your own projects and assignments.

How to use

  1. 1 Press Play to watch each element get inserted into the sorted left portion.
  2. 2 Use Step to advance one shift at a time and watch the key slide into place.
  3. 3 Type your own numbers into Custom input and press Apply.
  4. 4 Follow the highlighted pseudocode and the live comparison / write counters.

Why use this tool

  • See how the left side stays sorted while each new key shifts into position.
  • Step through every shift and comparison — ideal for understanding the inner while-loop.
  • Metrics show why insertion sort is fast on nearly-sorted data (close to O(n)).
  • Runs entirely in your browser. No signup, no uploads.

Frequently asked questions

What is insertion sort?

Insertion sort builds the sorted array one item at a time: it takes the next element (the key) and shifts larger elements right until the key lands in its correct spot.

What is the time complexity of insertion sort?

O(n²) average and worst case, but O(n) best case on already-sorted input. It is one of the fastest algorithms for small or nearly-sorted arrays.

Is insertion sort stable?

Yes — it only shifts elements that are strictly greater than the key, so equal values keep their relative order.

Why is insertion sort used inside other sorts?

Hybrid sorts like Timsort and introsort switch to insertion sort for small subarrays because its low overhead beats divide-and-conquer below a threshold.

What is Insertion Sort Visualizer?

An Insertion Sort Visualizer animates how insertion sort grows a sorted prefix by taking each next element and shifting larger elements right until the key lands in place. It shows the comparison and write counts that make insertion sort near-linear on already-sorted data.

Features

Step-by-step animation

Watch each element get inserted into the growing sorted prefix.

Complexity

Time: best O(n) (nearly sorted), average/worst O(n²). Space: O(1). Stable, in-place.

100% private

Runs entirely in your browser — nothing is uploaded.

Example

Input

[5, 2, 4, 1]

Output

insert 2 → [2,5]; 4 → [2,4,5]; 1 → [1,2,4,5] (sorted)

Common use cases

  1. 1

    Sort small / nearly-sorted data

    See why insertion sort is preferred for tiny or almost-ordered arrays.

  2. 2

    Understand stability

    Observe that equal elements keep their original order.

  3. 3

    Building block for TimSort

    Learn the insertion step used inside hybrid sorts like TimSort.

Summary

Zerethon's insertion sort visualizer animates the algorithm in your browser, building a sorted prefix one element at a time by shifting larger elements right. Insertion sort runs in O(n²) average and worst case, O(n) on a nearly-sorted array, with O(1) extra space; it is stable and in-place, and is efficient for small or almost-sorted inputs.

Category
Algorithm
Pricing
Free
Privacy
Browser-based
Signup
Not required

References

Privacy

Your data never leaves your browser unless explicitly stated. Insertion Sort Visualizer runs entirely client-side — no server upload, no logging, no tracking of your input.

New to this? Read the step-by-step explanation with Big-O analysis: Learn Sorting Algorithms →

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