This post contains some of the **best free big O notation calculator websites**. On these websites, you can easily calculate the complexity of your code in no time. All these websites ask is a piece of code. They already have support for some of the most popular programming languages such as C, C++, Java, and others. You just have to paste code corresponding to a programming language. And based on the number of loops in it, it will calculate the complexity or Big O notation for you.

In software engineering or computer science, big O notation is used **to categorize every algorithm depending on their time or space requirements. It basically tells how complex an algorithm will grow as we increase input size**. So basically, it helps you measure any function’s time or space complexity. And with the help of big O notation, we can predict how efficiently an algorithm will perform when used in an actual logic.

## 3 Free Big O Notation Calculator Websites to Calculate Code Complexity

## Shunnarski Big O Notation Calculator

Shunnarski Big O Notation Calculator is one of the best free websites that you can use to calculate code complexity on the go. Here this is an open-source tool and it supports C, C++, Java, C#, and JavaScript like languages to analyze. If you have some algorithm that you want to test for time and space complexity then you just implement it in one of the supported programming languages and submit it here. It generates the results instantly and you can use it any number of times.

You don’t need to sign up or register in order to use this tool. And if you want then you can also host it on your own server as well. So, just access the main homepage of this tool from the above link. After that, simply select a programming language from the list. Next, you just paste the code and make sure that it is error free and easily readable. Finally, hit the Get Big O! button and then it will show you the results. This is as simple as that. You can keep using this tool in this way and maybe in the later updates there will be support for other programming languages.

## Wolfram Alpha

Wolfram Alpha provides a simple tool called Big-O Domination Calculator that you can use. However, here this tool kind of works differently. Instead of analyzing complexity by analyzing the code, it analyses any two algorithms instead. You basically specify the parameters of the algorithms that you want to compare and it will help you decide which one is faster and more efficient. For now, this tool is in beta state and may fail on some inputs but I have hopes that it will work greatly when it comes out of beta testing.

Just access this tool from the link above and then start using it. There is no registration or Wolfram account required in order to use it. In the widget, you just enter the parameters for your algorithms and then hit the submit button. It will calculate the complexity and will show you which algorithm will dominate. This is as simple as that. You can keep using this tool in this way.

## AProVE

AProVE is another free website that you can use to calculate code complexity with ease. But here it works with Java bytecode only. It takes a Java code from you and then simply shows you the code complexity after running it. This is as simple as that. There are some other tools to inspect code execution on the website that you can use but they are meant for advanced users. To quickly, check Big O! notation of any Java code, you can use it easily.

Just follow the link above to reach the main website of this tool. Enter some Java code in the block and then simply submit the data. You can opt to generate the result in HTML or plain text format. It will take a few seconds to process the code you have submitted. After that, it will finally show you the code complexity that it has calculated. You can see it in action in the screenshot above.

### Final thoughts:

If you are looking for some best free websites to calculate the Big O notation then here are few that you can use. Although, you must know that not all programs can be analyzed programmatically to calculate their complexity, so the websites I have mentioned here will not work on all of them. You can try them on simple or linear algorithms but for complex ones. You will have to calculate the complexity manually.