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Merge Sort Visualizer — Animated, Step-by-Step

Animated merge 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 the array split into halves and merge back in sorted order.
  2. 2 Use Step to advance one merge comparison at a time.
  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 divide-and-conquer in action: recursive splits, then ordered merges.
  • Understand why merge sort guarantees O(n log n) on every input.
  • Metrics show the steady comparison count regardless of initial order.
  • Runs entirely in your browser. No signup, no uploads.

Frequently asked questions

What is merge sort?

Merge sort recursively splits the array in half until each piece has one element, then merges the pieces back together in sorted order.

What is the time complexity of merge sort?

O(n log n) in the best, average, and worst case. The log n comes from the halving depth and the n from merging each level.

Is merge sort stable?

Yes — when merging, equal elements take the one from the left half first, preserving original order.

What is the downside of merge sort?

It needs O(n) extra memory for the merge buffers, unlike in-place sorts such as heap sort or quicksort.

What is Merge Sort Visualizer?

A Merge Sort Visualizer animates the divide-and-conquer process of merge sort: recursively splitting the array into halves and merging them back in sorted order. It demonstrates the guaranteed O(n log n) running time and stable ordering.

Features

Step-by-step animation

Watch the recursive split and the merge of sorted halves.

Complexity

Time: O(n log n) in all cases. Space: O(n) auxiliary. Stable; not in-place.

100% private

Runs entirely in your browser — nothing is uploaded.

Example

Input

[38, 27, 43, 3]

Output

split → [27,38] & [3,43]; merge → [3, 27, 38, 43] (sorted)

Common use cases

  1. 1

    Guaranteed O(n log n)

    See why merge sort avoids quicksort's O(n²) worst case.

  2. 2

    Stable sorting

    Observe that equal keys preserve their input order.

  3. 3

    External / linked-list sort

    Understand why merge sort suits linked lists and external sorting.

Summary

Zerethon's merge sort visualizer animates the divide-and-conquer algorithm in your browser, recursively splitting the array and merging sorted halves. Merge sort runs in O(n log n) time in the best, average, and worst case, using O(n) auxiliary space; it is stable but not in-place. Its guaranteed O(n log n) makes it a reliable choice for large data and linked lists.

Category
Algorithm
Pricing
Free
Privacy
Browser-based
Signup
Not required

References

Privacy

Your data never leaves your browser unless explicitly stated. Merge 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 →

Compare

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