Kotlin Developer Hiring Guide


Forging the Future with Kotlin: A Comprehensive Hiring Guide for Developers

Embracing the cutting-edge potential of Kotlin, a rapidly ascending programming language, is a strategic move for any web development project aiming for unparalleled success. As the demand for web applications surges and user expectations reach new heights, hiring the right Kotlin developers becomes an imperative task. 

As businesses strive to deliver innovative solutions and delightful user experiences, Kotlin has risen to the forefront as a powerful programming language that empowers developers to achieve greatness. Its expressive syntax, robust features, and seamless integration with existing Java code make it a favorite choice for building versatile applications across multiple platforms.

In today’s comprehensive hiring guide, we unravel the essential aspects to consider when seeking top-tier Kotlin developers to join your web development team. From exploring their expertise in Kotlin-specific frameworks to assessing their problem-solving acumen, this article equips you with the knowledge to identify and onboard talented developers who can craft robust, scalable, and efficient web solutions. Whether you are launching a startup or driving transformation within an established enterprise, harnessing the expertise of Kotlin developers will undoubtedly be a game-changing asset, propelling your web development endeavors into the future.

If you are on the lookout for skilled Kotlin developers to bolster your team, this comprehensive hiring guide is your compass to navigate through the traits, skills, and potential pitfalls to ensure you onboard the best talent. Unlock the full potential of your team and propel your projects to new heights by understanding the unique advantages of hiring Kotlin developers who breathe life into your digital dreams.

1. What exactly is Kotlin?

Kotlin is a modern, statically-typed programming language developed by JetBrains, a software development company known for creating popular tools like IntelliJ IDEA. It was officially released in 2011 but gained significant popularity and adoption after Google announced it as an officially supported language for Android app development in 2017. Kotlin is designed to be fully interoperable with Java, allowing developers to seamlessly integrate Kotlin code with existing Java codebases.

The language is intended to address some of the shortcomings of Java and to provide a more concise, expressive, and safe programming experience. Some of the major features of Kotlin are:

  • Its concise syntax: Kotlin reduces boilerplate code, making it more concise and readable compared to Java.
  • Coroutines: Kotlin offers native support for asynchronous programming through coroutines, simplifying the handling of concurrent tasks.
  • Null safety types: Kotlin introduces nullable and non-nullable types, which helps avoid common null pointer exceptions, a common issue in Java.
  • Extension functions: Kotlin allows developers to add new functions to existing classes without modifying the class itself, enhancing code reusability.
  • Smart casting: Kotlin’s type system allows automatic type casting based on conditions, reducing the need for explicit casting in many scenarios.
  • Data classes: Kotlin has data classes that automatically generate standard methods like equals(), hashCode(), and toString(), streamlining the process of creating simple classes for holding data.
  • Functional programming support: Kotlin supports functional programming paradigms, including higher-order functions, lambda expressions, and more.

Due to its versatility, readability, and compatibility with existing Java ecosystems, Kotlin has found widespread use in various domains, including Android app development, web development, server-side applications, and more. Its continuous growth in popularity and adoption is a testament to its value as a powerful programming language that addresses modern development challenges.

2. Who is a Kotlin developer and why should you hire one for your web application development project?

 A Kotlin developer is a software developer who specializes in using the Kotlin programming language to build various types of applications, software solutions, and projects. Kotlin developers are well-versed in the language’s syntax, features, and best practices, allowing them to efficiently write clean, concise, and maintainable code.

Some of the key responsibilities of a Kotlin developer are;

  1. Application Development: Kotlin developers use the language to create a wide range of applications, such as Android mobile apps, web applications, server-side applications, desktop applications, and more.
  2. Code Writing and Maintenance: They write, review, and maintain Kotlin code, ensuring it meets high standards in terms of efficiency, readability, and scalability.
  3. Integration with Java: Kotlin developers often work on projects that require integrating Kotlin code with existing Java codebases, leveraging the seamless interoperability between the two languages.
  4. Problem-Solving: They are skilled at analyzing and solving complex programming challenges using Kotlin’s features, design patterns, and libraries.
  5. Testing and Debugging: Kotlin developers write unit tests and perform debugging to identify and resolve issues in the codebase, ensuring robust and bug-free applications.
  6. Code Optimization: They optimize Kotlin code for performance, making applications faster and more efficient.
  7. Adopting Kotlin Features: Kotlin developers stay updated with the latest language features, libraries, and frameworks, utilizing them to enhance development productivity and code quality.
  8. Collaboration: Kotlin developers work closely with other team members, such as UI/UX designers, backend developers, and project managers, to deliver cohesive and successful projects.

Kotlin developers often have a strong foundation in general software development principles, as well as an understanding of object-oriented and functional programming concepts. They might have prior experience in Java, as Kotlin’s interoperability with Java is one of its notable strengths. Kotlin developers can find opportunities in various industries, ranging from mobile app development and web development to backend services and software engineering roles. As Kotlin’s popularity continues to grow, the demand for skilled Kotlin developers is expected to increase as well.

3. Who is the most suitable for a web development project: a Kotlin developer or a Java developer?

When considering candidates for a web application development project, the choice between a Kotlin developer and a Java developer warrants meticulous evaluation, as each option presents distinct advantages. Kotlin, a modern programming language developed by JetBrains, has gained significant popularity in recent years, driven by its unique features and seamless interoperability with Java. In this context, several compelling reasons support the preference for a Kotlin developer, and these points can be summarized as follows:

  1. Conciseness and Readability: Kotlin’s concise syntax enables developers to express complex ideas with fewer lines of code compared to Java, promoting code readability and maintainability.
  2. Null Safety: Kotlin’s robust type system introduces nullable and non-nullable types, effectively addressing the notorious null pointer exceptions that frequently arise in Java development.
  3. Interoperability with Java: Kotlin is designed to seamlessly integrate with existing Java codebases, facilitating incremental adoption or collaborative development with Java developers.
  4. Modern Language Features: Kotlin boasts an array of modern language features, including extension functions, data classes, smart casts, and coroutines, fostering code organization and ease of implementation.
  5. Reduced Boilerplate Code: By significantly reducing boilerplate code, Kotlin streamlines the development process, allowing developers to focus on the core logic of the web application.
  6. Enhanced Type Inference: Kotlin’s smart type inference enables developers to write more concise and expressive code, enhancing code clarity and maintainability.
  7. Coroutines for Asynchronous Programming: With native support for coroutines, Kotlin simplifies the handling of asynchronous tasks, improving the responsiveness and scalability of web applications.

In contrast, while Java developers bring their own set of strengths and are instrumental in well-established Java-based projects, Kotlin developers provide a distinctive set of benefits that align well with new web application initiatives seeking modern development practices and accelerated efficiency. The growing Kotlin community further fortifies the case for hiring Kotlin developers, granting access to a wealth of libraries, frameworks, and community support that can propel web application development endeavors to new heights. Ultimately, the selection between Kotlin and Java developers should be carefully deliberated, factoring in the specific requirements of the web application project, the existing team’s expertise, and the desired development approach.

4. Should you hire an in-house Kotlin developer or a freelance Kotlin developer?

4.1 Who is an in-house developer and a freelance developer?

 An in-house developer is a permanent employee of a company or organization, hired through formal employment processes to work exclusively for the company on a full-time or part-time basis. They are dedicated team members who collaborate closely with other employees and stakeholders, contributing to long-term projects and providing stability and continuity in the development process. In-house developers receive benefits and are deeply integrated into the company’s culture and objectives. 

On the other hand, a freelancer, also known as a contractor, is a self-employed individual who operates independently and offers their services to multiple clients. They are engaged on a project-by-project basis, providing flexibility and specialized skills to tackle specific tasks or initiatives. Freelancers typically work remotely and are hired under contractual agreements for the duration of the specific project. Their status as independent contractors means they manage their own taxes and business expenses. The choice between an in-house developer and a freelancer depends on the project’s scope, timeline, and the desired level of long-term commitment and collaboration.

4.2. Whom should you hire: a freelancer or an in-house developer?

The decision of whether to hire an in-house Kotlin developer or a freelance Kotlin developer for your web development project depends on various factors, each carrying its own set of advantages and considerations. Let’s consider the key aspects of each option.

In-house Kotlin Developer:


  1. Dedicated Commitment: An in-house Kotlin developer is a permanent member of your team, fully dedicated to your web development project, fostering a sense of ownership and accountability.
  2. Immediate Availability: In-house developers are readily available for collaboration, meetings, and discussions, leading to quicker response times and smoother communication.
  3. Cohesive Team Environment: In-house developers work closely with other team members, enhancing teamwork, knowledge sharing, and efficient project coordination.
  4. Long-term Collaboration: Hiring in-house fosters the potential for long-term collaboration, allowing developers to deeply understand your organization’s goals and build strong relationships.


  1. Cost: Employing in-house developers involves expenses such as salaries, benefits, office space, and equipment, which can be more substantial than freelance rates.
  2. Resource Management: Hiring in-house means taking responsibility for resource management and ensuring a steady stream of projects to keep the developer engaged.
Freelance Kotlin Developer:


  1. Flexibility: Freelancers offer flexibility in terms of contract duration and availability, allowing you to hire them for specific project phases or tasks.
  2. Cost Efficiency: Freelancers are often more cost-effective, as you pay for their services only when needed, without additional overhead expenses.
  3. Specialized Skills: Freelancers often have diverse experience, offering specialized skills and expertise that can be valuable for specific aspects of your web development project.
  4. Quick Onboarding: Freelancers are accustomed to adapting quickly to new projects, requiring minimal onboarding time.


  1. Availability and Commitment: Freelancers may be working on multiple projects simultaneously, which could impact their availability and responsiveness.
  2. Communication Challenges: Working with remote freelancers may present communication challenges, especially across different time zones and through digital channels.
  3. Integration with Team: Freelancers may not have the same level of familiarity with your organization’s processes and culture as in-house developers.

Ultimately, the choice between hiring an in-house Kotlin developer or a freelance Kotlin developer hinges on the project’s scope, timeline, budget, and your team’s existing capabilities. For long-term and extensive projects that require consistent involvement and close collaboration, an in-house developer may be a better fit. On the other hand, for short-term projects with specialized requirements or when cost-effectiveness and flexibility are critical, a freelance Kotlin developer might be the ideal choice. As with any hiring decision, carefully evaluating the specific needs and goals of your web development project will guide you toward the most suitable option.

5. Some questions to ask when you are interviewing a Kotlin developer

When you are hiring a developer for any programming language, it is necessary to interview them and examine their knowledge and experience. We have listed out some of the proficiencies to check when you are looking to hire a Kotlin developer.

Technical Proficiency

  • What attracted you to Kotlin programming, and what do you find most appealing about the language?
  • Can you explain Kotlin’s nullable types and how they differ from traditional nullable types in other languages?

Kotlin proficiency

  • Can you describe the differences between val and var in Kotlin? During which scenarios do you use them?
  • How do you handle null safety in Kotlin, and what are the benefits of doing so?

Check for Android development knowledge (not required but would be an added point)

  • Have you worked on Android projects using Kotlin? If yes, describe your experience and highlight any specific challenges you faced and how you overcame them.
  • How do Kotlin’s features contribute to writing cleaner and more concise codes in Android applications?

Backend proficiency

  • Have you used Kotline for backend development? Describe the framework and libraries you used and the benefits they provide.
  • Why is Kotlin interoperable with Java? How does Kotlin’s interoperability with Java impact your backend development process?
  • Have you used Kotlin Coroutines in your projects? What is the purpose of using them, and how do they simplify asynchronous programming in Kotlin?

Experience with third-party libraries

  • Have you tried using any popular Kotlin libraries such as Room, Ktor, and kotlinx.serialization? Tell us how they enhance the overall development process.

Skills check

  • Can you explain a challenging problem you encountered during Kotlin development and how you approached it and solved the problem?
  • How do you ensure code quality and maintainability in your Kotlin projects? 
  • What specific coding standards and tools do you use?
  • How do you stay up-to-date with the latest advancements in Kotlin and related technologies?
  • Have you tried contributing to any Kotlin open-source projects or participated in Kotlin-related communities?
  • What is your approach to ensuring effective communication and collaboration within a development team?
  • Have you worked on projects where Kotlin developers collaborated with developers using other programming languages?

When doing an interview to hire a developer, make it a point to ask for sample Kotlin projects, or at least for a portion of sample coding, and also provide them with a code piece and ask them to review the code, identify potential improvements, and then ask for an explanation for their proposed process. 


In conclusion, the comprehensive hiring guide for Kotlin developers has provided valuable insights into the key consideration and the strategies to find the best and the most talented developers for your development project. Kotlin’s rise in popularity, backend by its concise syntax, interoperability, and strong tooling support, has solidified its position as a preferred language for modern software development. By understanding the essential skills, experience, and qualities of an exceptional Kotlin developer, you can confidently get onto the market and start your hunt for the most ideal candidates. 

By assembling a team of skilled Kotlin developers, you set the stage for building robust and scalable applications that cater to the evolving needs of the digital landscape. As technology continues to advance, the demand for Kotline’s versatility and adaptability will only grow, making it a prudent investment in the success of your software development endeavours.

Previously at
Flag Argentina
time icon
Experienced Android Engineer specializing in Kotlin with over 5 years of hands-on expertise. Proven record of delivering impactful solutions and driving app innovation.