Kotlin Coding Tests

Looking to hire Kotlin developers? Make sure they can write solid, reliable code and build Android apps or cross-platform solutions that take full advantage of Kotlin’s unique features and best practices.

TestGorilla’s selection of 12 universal coding tests can help you assess programming skills across 20 languages, including Kotlin. With these tests, you can identify developers who think on their feet, deliver creative solutions, and make an impact on your most important projects.

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What is a Kotlin skills test?

Kotlin is a modern, statically typed programming language designed to work seamlessly with Java.

It’s known for its concise syntax, safety features, and versatility in Android app development, cross-platform projects, and server-side applications (programs that handle backend tasks like databases, APIs, and business logic).

When you’re hiring Kotlin developers, their resumes and cover letters won’t tell you much about their practical coding abilities or how well they understand Kotlin's unique features. To truly understand their skills, you need a way to assess their real-world coding expertise. That’s where Kotlin online tests come in.

Kotlin skills tests are designed by software engineering experts, covering key areas like working with data structures, tackling Android development challenges (like architecture and networking), and mastering Kotlin’s language features, syntax, and programming principles.

These tests also evaluate proficiency in writing efficient code and using the Kotlin standard library, giving you confidence in your candidates’ ability to meet the demands of your projects.

Why use Kotlin skills tests?

Screen for Kotlin skills – including syntax and language features, object-oriented programming principles, working with arrays, Android app architecture, networking, and database management – or even relevant soft skills like communication.
Test their ability to handle real-world challenges, like managing UI/UI interactions or working on backend systems
Use validated tests with built-in anti-cheating measures so you know the results reflect a candidate’s actual abilities.
Let candidates choose from 19+ programming languages – so you can focus on their problem-solving skills, not just the code they write.
Go beyond the final score by reviewing how they approached the problem, structured their code, and debugged along the way.
Stop hiring developers who won’t succeed – 97% of employers using skills-based approaches in their tech recruitment have reduced their mis-hires.

What roles can you hire for with a Kotlin coding test?

Android developer

These developers use Kotlin to create feature-rich Android apps. They specialize in app architecture, UI/UX design, database management, and integrating with RESTful APIs – keeping mobile experiences smooth and scalable.

Mobile application developer

Developers in this role create cross-platform apps with Kotlin Multiplatform, using shared code to simplify development and maintain consistency across Android and iOS.

Back-end developer

Back-end developers use Kotlin to build strong, scalable server-side systems. They handle tasks like API development, database integration, and asynchronous programming, often working with frameworks like Spring Boot.

Software architect

Kotlin software architects plan and guide the development of mobile or cross-platform apps. They focus on building systems that are easy to update, work well under heavy use, and meet the specific needs of the business.

12 programming skills tested in Kotlin and 19 other coding languages

Evaluate 12 essential programming skills with coding challenges and simulated tasks. Let candidates solve problems using Kotlin or any of 19 additional programming languages based on their expertise and experience.

Coding: Data Structures - Stacks and Queues

This intermediate-level coding challenge assesses candidates' proficiency in manipulating stacks and queues. You can configure which programming languages will be available for your candidates.

35 min

Details

Coding: Debugging

This intermediate-level coding challenge focuses on candidates’ ability to interpret and debug code, based on a set of requirements, in the programming language of their choice. You can configure which programming languages will be available.

35 min

Details

Coding: Entry-Level Algorithms

This coding test assesses candidates' ability to program a basic algorithm, in the programming language of their choice. You can configure which programming languages will be available for your candidates to choose from.

15 min

Details

Coding: Intermediate-Level Algorithms

This coding test assesses candidates' intermediate-level programming skills, in the programming language of their choice. You can configure which programming languages will be available for your candidates to choose from.

35 min

Details

Coding: Data Structures - Heaps

This intermediate-level coding challenge assesses candidates' proficiency in working with heaps, in the programming language of their choice. You can configure which programming languages will be available for your candidates.

35 min

Details

Coding: Data Structures - Graphs

This intermediate-level coding challenge assesses candidates' proficiency in graph data structures. You can configure which programming languages will be available for your candidates.

35 min

Details

Coding: Data Structures - Binary Search Trees

This intermediate-level coding challenge assesses candidates' proficiency in working with binary search trees, in the programming language of their choice. You can configure which programming languages will be available for your candidates.

35 min

Details

Coding: Data Structures – Binary Trees

This intermediate-level, language-agnostic coding challenge assesses candidates' proficiency in manipulating binary trees, enabling candidates to choose their preferred programming language. Employers can configure supported languages as needed.

35 min

Details

Coding: Data Structures – Linked Lists

This intermediate-level coding test evaluates candidates' ability to manipulate linked lists, in the programming language of their choice. You can configure which programming languages will be available for your candidates.

35 min

Details

Coding: Data Structures - Arrays

This intermediate-level coding test evaluates candidates' ability to manipulate arrays, crucial for code optimization, in the programming language of their choice. You can configure which programming languages will be available for your candidates.

35 min

Details

Coding: Data Structures – Strings

This intermediate-level coding challenge assesses candidates' proficiency in manipulating strings. You can configure which programming languages will be available for your candidates.

35 min

Details

Coding: Data Structures - Hash Tables

This intermediate-level coding challenge assesses candidates' proficiency in working with hash tables, in the programming language of their choice. You can configure which programming languages will be available for your candidates.

35 min

Details

Designed by Kotlin experts

TestGorilla's tests are carefully crafted by a team of subject matter experts with extensive experience in software development and assessment design. Each test is rigorously peer-reviewed, calibrated with feedback from hundreds of test takers, and regularly updated.

Suneet holds an MSc in video game development and brings 10+ years of industry experience across native Android, iOS, web, and game development. Currently serving as Director of Engineering for a payroll management app, Suneet has done extensive work in Android development and backend systems.

Ashleigh is a seasoned Android app developer with more than five years’ experience working professionally with Kotlin and Java. Combining her programming skills with a background in industrial-organizational psychology and analytics, Ashleigh develops tests that focus on both technical expertise and practical problem-solving.

Image of the subject-matter expert for this test

With 19 years of software engineering experience, Patrick specializes in RESTful frameworks and API integration. He’s built and scaled a successful web development agency and continues to lead innovative projects. Patrick’s expertise in backend development and APIs helps ensure candidates are tested on key backend skills.

Gary is a data scientist with a strong background in machine learning and data analysis. With degrees in economics and computer science, Gary write tests that challenge candidates to think critically and create code for data-heavy applications.

Built-in features to support your Kotlin assessment

Want to maximize your chances of hiring the best Kotlin developer for the role? We recommend multi-measure testing.

By pairing your coding test with other relevant tests that evaluate your candidates' soft skills, cognitive abilities, knowledge, and preferences you can ensure you shortlist talent that's ready to contribute from day one.

Our in-depth Kotlin coding report offers insights into the approach each candidate took to arrive at their answers. The report includes:

🔹 Percentile-based scoring of candidates based on overall correctness (whether given inputs produce the correct output)

🔹 A timeline showing how candidates arrived at their answer, with specific actions such as copy/pastes highlighted for easy reference

🔹 A dynamic solution window, showing the candidates' final code coming together over time

🔹 Candidates' responses and results for each test case as well as the final validation use case

See what it looks like in action

All tasks and scenarios are solved in this integrated development environment (IDE). Once the candidate assesses the problem, they can choose Kotlin as their preferred language from the drop-down menu and solve the question.

Get started with your Kotlin coding test

Ready to start testing for Kotlin skills? Screen developers in three easy steps.

1. Create your assessment

Choose an existing universal coding test or create your own custom challenge. Select from up to 20 languages to include in your test including Kotlin, Java, and Swift.

2. Invite candidates your way

Connect with candidates by sending email invites directly from TestGorilla, straight from your ATS, or by sharing a direct link.

Illustration representing employees liking skills-based hiring

3. Analyze and shortlist top coders

Evaluate candidates’ Kotlin and coding skills, plus soft skills. Use our dashboard and reports to identify top performers.

Kotlin coding test FAQs

Creating a custom coding test with TestGorilla is easy. Just pick Kotlin from the 20 options, write a short test description, outline the problem with the expected inputs and outputs, and set up test cases to check how efficient candidates’ code is. You can also select multiple programming languages the test-taker can use – including Kotlin – to give them more freedom and learn more about their skills.

Our users can create assessments in just minutes. This simple process involves selecting up to five tests from our test library, which our system will combine into one assessment that you can use to test your Kotlin candidates. For instance, you might select our Data Structures - Stacks and Queues test plus another coding test, along with one or two soft skills tests. You can also add custom questions to individual tests and include your custom coding tests (both these steps will take a bit longer).

Start by checking the candidate’s overall score, which reflects the percentage of passed validation cases. Then, interpret the coding assessment in the "View Report" section. Use the timeline feature to watch how the candidate wrote their Kotlin code, step by step, and identify any copied or pasted sections (highlighted in yellow).

Review test cases to see how the candidate tested their code, then review validation cases to confirm if their final solution met the requirements.

Our users can create assessments in just minutes. This simple process involves selecting up to five tests from our test library, which our system will combine into one assessment that you can use to test your Kotlin candidates. For instance, you might select our Data Structures - Stacks and Queues test plus another coding test, along with one or two soft skills tests. You can also add custom questions to individual tests and include your custom coding tests (both these steps will take a bit longer).

Creating a custom coding test with TestGorilla is easy. Just pick Kotlin from the 20 options, write a short test description, outline the problem with the expected inputs and outputs, and set up test cases to check how efficient candidates’ code is. You can also select multiple programming languages the test-taker can use – including Kotlin – to give them more freedom and learn more about their skills.

Start by checking the candidate’s overall score, which reflects the percentage of passed validation cases. Then, interpret the coding assessment in the "View Report" section. Use the timeline feature to watch how the candidate wrote their Kotlin code, step by step, and identify any copied or pasted sections (highlighted in yellow).

Review test cases to see how the candidate tested their code, then review validation cases to confirm if their final solution met the requirements.