Top 10 Kotlin Libraries to Know in 2024

In the huge landscape of programming languages, Kotlin has emerged as a powerful programming language and has received tremendous popularity among programmers. The Kotlin language is not just limited to Android development; it’s also used in server-side programming and beyond.

One of the reasons behind its popularity and adoption is its rich ecosystem of libraries, which simplifies the development process and enhances the developer’s productivity. Today, in this article, we will take a look at the top 10 Kotlin libraries that will remain indispensable in 2024. Let’s get started.

What is Kotlin?

Developed by JetBrains Kotlin is a modern programming language that was introduced in 2011 as an alternative to Java, targeting the Java Virtual Machine (JVM). It was initially launched to be used as a plugin in Android Studio. Later in May 2017, it was declared the official Android development language by Google. Kotlin is not limited to Android development but is also used in various software development domains, which include backend development, desktop application development, and data science and analytics.

The reason for introducing Kotlin was to address various lacking features in existing programming languages, particularly Java while maintaining seamless interoperability with Java. Nowadays, Kotlin has become the most popular among developers, and its community has increased on a large scale.

Top 10 Kotlin Libraries to Know in 2024

1. Ktor

Ktor is a powerful asynchronous framework that is used to build connected systems, which include web applications, HTTP services, and more. Ktor was developed by JetBrains, which is the same company that designed Kotlin itself, leveraging Kotlin’s concise and expressive syntax to provide a flexible framework for developing server-side applications.

Key Features

• An asynchronous programming model that allows developers to write non-blocking, asynchronous code to achieve high concurrency.
• Ktor follows a modular architecture, allowing developers to integrate and customize only the required modules.
• For defining routes, Ktor uses a type-safe DSL, which makes HTTP request and response handling simpler.
• To provide runtime and interactive web applications, Ktor has built-in support for web sockets and server-sent events.

2. Coroutine

Coroutine has become an important part of Kotlin programming. A coroutine is a framework that is used to manage multiple threads asynchronously. It provides developers with a way to write asynchronous code sequentially. It simplifies asynchronous programming tasks such as making network requests, accessing databases, and long UI operations. With its concurrency mechanism, developers can write functions that can be paused and resumed when required.

Key Features

• The coroutine allows it to suspend its execution when needed and allows other code to run before it resumes its execution (with the use of the await keyword).
• The coroutine runs within the event loop, which takes care of scheduling and executing multiple coroutines. This event loop ensures the execution of the coroutine in an orderly manner.
• Coroutine is well known for managing resources efficiently, such as network sockets and DB connections.

3. Room Database

Provided by the Jetpack Architecture Component, Room is a persistence database library. Room is nothing but an abstraction layer above the SQLite database, which is an open-source RDBMS. It simplifies the process of creating tables, along with database CRUD operations. With room, developers can easily migrate in case any changes in the database structure are required, such as adding a new column or changing the data type of a column.

Key Features

• The room allows developers to work with SQLite databases by defining annotations on Java/Kotlin classes and objects. It simplifies database operations by mapping database tables with annotated classes and objects.
• To catch errors in query compile time, Room performs compile-time validation checks on queries. This helps to increase code readability.
• Room database is also compatible with RxJava and Coroutine; it allows developers to use RxJava observer and Coroutine to perform asynchronous operations.
• Room database allows developers to seamlessly integrate it with LiveData. LiveData help can be used when it’s needed to observe changes in the database and notify the UI.

4. Koin

Koin is a lightweight dependency injection framework mainly designed for Android development. Unlike Dagger, developers can easily manage dependency injections across the application. Koin offers DSL (domain-specific language) to manage dependency and give support to Android and other platforms such as JVM and iOS.

Key Features

• With Coin, dependencies are defined within modules, which can be easily configured and composed using DSL syntax, making it simpler to manage dependencies.
• Koin does not use code generation and reflection at runtime; instead, it uses Kotlin’s DSL capabilities to resolve dependency at compile-time only.
• Coni offers constructor injection, where dependencies are passed in constructor arguments; this promotes more modular code design.
• Coin has a rich community and contributors, along with rich documentation and ready-made examples that developers can use to get started.

5. Ktor-http-client

Built on top of Ktor, ktor-http-client is a powerful HTTP client library. With the use of Ktor-http-client, developers can make fluent HTTP requests asynchronously, with the support of such things as request and response transformation and HTTP cookies.

Key Features

• Ktor-http-client provides support for HTTP request and response bodies, which means users can easily convert those bodies into formats such as JSON, XML, and other custom formats.
• Ktor-http manages the connection pool automatically, optimizes resource usage, and improves performance by reusing connections for multiple requests.

6. Exposed

Exposed is a lightweight SQL library for Kotlin, mainly used for database operations. The intent behind designing the Exposed library is to provide an API and leverage Kotlin features that offer a more concise and easy way to access the database. It uses DSL for defining the DB schema, query, and operation directly in the Kotlin code. Using these DSL methods, developers can write code that is concise and easily readable.

Key Features

Exposed leverages Kotlin’s type safety mechanism to ensure type safety within database queries. It makes use of Kotlin to represent database tables, columns, and results of queries.

• With Expsed, developers can define database schema using Kotlin code itself rather than the SQL DDL statements. This means tables, columns, and constraints can be declared using Kotlin classes and functions.
• Exposed is open-sourced and hosted publicly on Github, which allows other developers to contribute enhancements, features, and bug fixes.
• It supports multiple SQL database backends, which include SQLite, MySQL, and H2.

7. Fuel

Fuel is a lightweight HTTP networking library for Kotlin and Android. Fuel is designed to simplify the process of making HTTP request calls and handling the response. It allows you to perform HTTP operations such as GET, PUT, POST, DELETE, and more by using its concise and expressive APIs. Fuel gives developers the provision to make asynchronous or synchronous request calls. The support of customization allows developers to add custom features, interceptors, serializers, and authentication mechanisms.

Key Features

• Provides a concise way to make HTTP requests. Provides an easy way to specify requests, headers, and bodies for developers.
• Support synchronous and asynchronous HTTP requests. It allows developers to choose between making requests asynchronously using Kotlin coroutines or synchronously using blocking calls.
• Using a fluent API, developers can specify query parameters and headers for HTTP requests.
• It supports a range of HTTP methods, including GET, POST, PUT, DELETE, PATCH, HEAD, and OPTIONS.

8. Arrow

Inspired by Haskell’s standard libraries, Arrow is a library for functional programming in Kotlin that provides a set of data types and type classes. It enables developers to use functional programming patterns like monads, functors, and applicatives in Kotlin. For concurrency and asynchronous programming, Arrow provides type-sabe abstractions, including data types IO and DeferredK.

Key Features

• Arrow supports functional data types such as Option, Either, Try, Validated, State, IO, SequenceK, ListK, NonEmptyList, Tuple, and more.
• Arrow supports the implementation of type classes such as Functor, MonadError, Applicative, Monad, Monoid, Foldable, Traverse, Semigroup, Ord, and more.
• Arrow offers utilities for property-based testing with the use of libraries such as Kotlintest and arrow-recursion.

9. Retrofit

Retrofit is the most popular and widely used type-safe HTTP client library for Android and Java, developed by Square. Retrofit simplifies the process of making HTTP requests and reduces the boilerplate code required for making HTTP calls. Retrofit automatically converts responses received from the server into Kotlin or Java classes. Using Interceptor, a developer can intercept and modify HTTP requests and responses. Retrofit provides constants that developers can use to print requests and responses in the console log.

Key Features

• Retrofit generates an interface for defining HTTP endpoints that allows developers to declare method signatures for their RESTful network operations.
• To configure API endpoints, request parameters, and headers, Retrofit uses an annotation mechanism, such as @GET, @POST, @Path, and more.
• Retrofit has built-in support for popular serialization formats such as JSON, XML, and Form URL-Encoder.
• Retrofit supports an interceptor, which is very useful in tasks such as logging, authentication, and error handling.

10. MockK

MockK is a mocking library that provides DSL for creating stubs and mocks while writing unit test cases. It offers a concise syntax for defining mock behavior and allows seamless integration with the most popular frameworks, such as JUnit and Spek. For defining mock behavior and expressions, MockK uses Kotlin DSL. This DSL leverages Kotlin’s syntax features, such as lambda expressions, extension functions, and infix functions, to provide a concise API for working with mock objects.

Key Features

• Specifically designed for Kotlin, it leverages its concise syntax and other features to simplify writing test cases.
• It supports mocking classes and interfaces that allow developers to create mocks of any type.
• It allows stubbing method calls on mock objects, specifying a return value, or setting expectations of what to send when methods are invoked.
• Offers rich and detailed documentation that allows developers to get started with writing test cases.

Conclusion

The above-listed libraries cover a range of use cases and requirements for Kotlin development, from mobile development to web and backend services, from dependency injections to mocking classes and objects. Considering these libraries used in our project helps to increase code quality and productivity. As Kotlin’s popularity continues to gain, these libraries are likely to remain essential for Kotlin developers in the year 2024 and beyond.