A library is an assembly of precompiled routines that a programming use while coding for a software or website. If you are a programmer and looking for some of the best programming libraries in 2021, then this article is very helpful for you.
JetBrains’ ReSharper
Easily by far the most useful and best C# library, with it automating most of what you usually had to do manually. It’s just a gigantic time saver with you being able to make a class inside of main. And just right-clicking it and sending it to its own separate file without having to add anything else to it, and it works. ReSharper takes the care regarding efficiency and popularity, with almost all professional C# developers using it as their go-to refactoring tool. But even that does not do it justice with how much power and capabilities it provides for developers.
From Code Generation, Code Assistance, Navigation, and Search, to Code Analysis ReSharper can pretty much do it all for you.

JUnit
A popular java unit testing library and one of the best and most widely adopted libraries in Java. If a developer makes a mistake while programming in Java, you will get a compilation error or a build error. But if the developer makes a logical error, it leads to runtime, none intended behavior, which is a disaster for companies.
JUnit provides an easier life regarding unit testing and allows developers to be more certain of how their software or application really works. Although the learning curve is steep and challenging. It’s a very good practice to start incorporating unit testing into your projects.

JSON Jackson and Gson
Previously the go-to parsing library was XML. But that is no longer the case JSON is just much clearer and easier than this. Which has much more documentation and coding tutorials. It’s simple and yet effective nature allowed it to replace XML which has ruled the market for years.

Just the fact that it was capable of dethroning XML should tell you more than any words could ever. Jackson and Gson are JSON libraries that even make serializing and deserializing Java objects and other objects to JSON just make your life so much easier. And it is a must-have tool, and you can pick which library you prefer between Jackson and Gson.
TensorFlow
By far the best library for Artificial Intelligence developed by Google. TensorFlow provides an environment that allows primarily training by inference for neural networks. This allows developers to build large scale neural networks and Tensor flow is mainly used for:
- Classification
- Perception
- Understanding
- Discovering
- Prediction
The C++ Standard Library
Although one would think the word Standard means this is how C++ comes built-in, that is not the case. The C++ Standard Library extends the initial functionality of regular C++. It also provides gigantic improvements in usage and data structures. This simply were not present in Vanilla (no add-ons or tools or added libraries) out-of-the-box C++.
This library provides many generic concepts that really enhance the C++ developer’s capabilities. As a result it makes coding a much smoother experience. Since C++ is the hardest to adapt to between all programming languages.

Final thoughts
Every library has some ups and downs, and we will always need to watch out for package size. And makes sure the libraries don’t use up too much space and end up causing more harm than good and slowing down the program or application instead of improving it.
It is impossible to mention all the useful programming libraries. Because each language has hundreds of used and unused or libraries that are excellent but not widely adopted yet. But hopefully these best ever programming libraries will help you in your programming journey. Moreover, you will feel more comfortable with your respective programming languages and frameworks of choice.