10 Reasons to Try Kotlin Multiplatform (updated 2025)

Those in the know will surely be aware that the Kotlin ecosystem has been transforming. Thanks to new compilers, libraries, and frameworks, Kotlin has become a multiplatform environment. You can develop compelling apps on the desktop, iOS, Android, and even WebAssembly – all from a single codebase. As such, Kotlin Multiplatform is now in direct competition with technologies like Flutter and React Native.

Is multiplatform development a realistic proposition? What should drive you to choose Kotlin Multiplatform over the alternatives? In this talk, I’ll take a close look at the Kotlin Multiplatform technology and ecosystem and offer ten compelling reasons why you should give it a go!

Transcript

1. 10 Reasons To Try Kotlin Multiplatform Pamela Hill Developer Advocate - JetBrains
2. Do you agree with the following statements?
3. “I want to avoid code duplication by sharing code on a variety of platforms using an awesome, modern language.”
4. “I want to adopt this technology flexibly in my new and existing projects with minimal risk.”
5. “I want to know I’m not alone in this journey of adoption.”
6. Kotlin Multiplatform by JetBrains is for you!
7. Before Kotlin Multiplatform Business / Domain (Entities, Use Cases, Interactors) Data / Core (Repositories, HTTP Clients, Cache) UI (Views) Presentation (Presenters, View Models, Controllers) iOS Business / Domain (Entities, Use Cases, Interactors) Data / Core (Repositories, HTTP Clients, Cache) UI (Views) Presentation (Presenters, View Models, Controllers) Android Business / Domain (Entities, Use Cases, Interactors) Data / Core (Repositories, HTTP Clients, Cache) UI (Views) Presentation (Presenters, View Models, Controllers) Desktop
8. With Kotlin Multiplatform iOS Android Desktop Platform-specific code Platform-specific code Platform-specific code Kotlin Multiplatform Anything you want to share
9. • Server (JVM) • Mobile (Android, iOS) • Desktop (macOS, Windows, Linux) • Web (JS, Wasm) What platforms are supported?
10. “I want to avoid code duplication by sharing code on a variety of platforms using an awesome, modern language.”
11. 1. Avoid duplication
12. The story of Wonder by https://kotlinlang.org/lp/multiplatform/case-studies/baidu #1: Avoid duplication
13. The problem with native app dev https://kotlinlang.org/lp/multiplatform/case-studies/baidu • Inconsistencies in the app experience • High cost of verifying the business logic • High upgrade and maintenance costs #1: Avoid duplication
14. “The complex and inconsistent business logic of the iOS and Android platforms led to increasing maintenance costs for the app.” - Baidu #1: Avoid duplication
15. Unifying data layer https://kotlinlang.org/lp/multiplatform/case-studies/baidu • Data model • RESTful API requests • JSON data parsing • Caching logic #1: Avoid duplication
16. Adopting MVI to unify interface logic https://kotlinlang.org/lp/multiplatform/case-studies/baidu • Low-level data • Processing logic • UI processing logic #1: Avoid duplication
17. The results ✓ Consistent experience ✓ Reduced cost of maintenance ✓ Reduced cost of testing ✓ Improved productivity https://kotlinlang.org/lp/multiplatform/case-studies/baidu #1: Avoid duplication
18. 2. Extensive list of supported platforms 1. Avoid duplication
19. What kind of platforms? Server Android iOS Desktop Web Kotlin Multiplatform Wasm JS #2: Extensive list of supported platforms
20. What is Wasm? • WebAssembly (Wasm) is a binary instruction format for portable virtual machines • Smaller, faster than JavaScript • Write code in languages like Kotlin / Go / Rust, compile to Wasm • Already supported in most modern browsers, Node.js #2: Extensive list of supported platforms
21. The story of uizlet https://kotlinlang.org/lp/multiplatform/case-studies/quizlet/ #2: Extensive list of supported platforms
22. Tried other technologies https://kotlinlang.org/lp/multiplatform/case-studies/quizlet/ • JavaScript • React Native • C++/Rust/Go #2: Extensive list of supported platforms
23. Settled on Kotlin Multiplatform Android iOS Web Kotlin Multiplatform https://kotlinlang.org/lp/multiplatform/case-studies/quizlet/ #2: Extensive list of supported platforms
24. The results ✓ Type-safe APIs when marshalling objects ✓ Performance on Android/iOS improved ◦ 25x faster grading algorithm on iOS compared to JavaScript ✓ Android app size decreased ◦ 18MB down to 10MB ✓ Better developer experience ✓ Different team members keen to try writing shared code #2: Extensive list of supported platforms
25. Another scenario: sharing code between clients/server #2: Extensive list of supported platforms
26. Before: Sharing data models Use a language-neutral, platform-neutral language like Protocol Buffers ✓ Use with any language - like Go ⛌ Need to learn yet another format ⛌ Need to generate data classes from .proto files on all platforms #2: Extensive list of supported platforms
27. Sharing data models with Kotlin Multiplatform ✓ Use a familiar language with great tooling ✓ Write once, use everywhere ? Does it work with all your languages (server-side: only JVM) #2: Extensive list of supported platforms
28. 3. Kotlin is a loved & trusted language for everyone 1. Avoid duplication 2. Extensive list of supported platforms
29. What do people say about Kotlin? • Concise • Expressive • Original • Sound https://www.youtube.com/watch?v=PsaFVLr8t4E (2018) #3. Because Kotlin
30. Kotlin aims to be pragmatic • Readability over concision • Reuse over expressiveness • Interoperability over originality • Safety & tooling over soundness https://www.youtube.com/watch?v=PsaFVLr8t4E (2018) #3. Because Kotlin
31. Kotlin is designed to make developers happier 😊 #3. Because Kotlin
32. #3. Because Kotlin 92% of developers enjoy using Kotlin
33. How does Kotlin make developers happier? • Makes developers more productive • Fewer crashes • Improved safety, correctness #3. Because Kotlin https://kotlinlang.org/docs/android-overview.html (2023) https://medium.com/androiddevelopers/fewer-crashes-and-more-stability-with-kotlin-b606c6a6ac04 (2020)
34. Where is Kotlin used? #3. Because Kotlin
35. #3. Because Kotlin
36. 99% Of top 1000 apps on Google Play use Kotlin #3. Because Kotlin
37. Kotlin Web Frameworks https://kotlinlang.org/lp/server-side/ #3. Because Kotlin
38. “I want to adopt this technology flexibly in my new and existing projects with minimal risk.”
39. 4. Choose what to share, what to write natively
40. Before Kotlin Multiplatform Business / Domain (Entities, Use Cases, Interactors) Data / Core (Repositories, HTTP Clients, Cache) UI (Views) Presentation (Presenters, View Models, Controllers) iOS Business / Domain (Entities, Use Cases, Interactors) Data / Core (Repositories, HTTP Clients, Cache) UI (Views) Presentation (Presenters, View Models, Controllers) Android Business / Domain (Entities, Use Cases, Interactors) Data / Core (Repositories, HTTP Clients, Cache) UI (Views) Presentation (Presenters, View Models, Controllers) Desktop #4: Choose what to share, what to write natively
41. Sharing Business Logic Business / Domain (Entities, Use Cases, Interactors) Data / Core (Repositories, HTTP Clients, Cache) UI (Views) Presentation (Presenters, View Models, Controllers) iOS Kotlin Multiplatform Shared Module UI (Views) Presentation (Presenters, View Models, Controllers) Android UI (Views) Presentation (Presenters, View Models, Controllers) Desktop #4: Choose what to share, what to write natively
42. Sharing UI Logic Business / Domain (Entities, Use Cases, Interactors) Data / Core (Repositories, HTTP Clients, Cache) UI (Views) iOS Kotlin Multiplatform Shared Module UI (Views) Android UI (Views) Presentation (Presenters, View Models, Controllers) Desktop #4: Choose what to share, what to write natively
43. With ✨ Compose Multiplatform✨ Business / Domain (Entities, Use Cases, Interactors) Data / Core (Repositories, HTTP Clients, Cache) iOS Kotlin Multiplatform Shared Module UI (Views) Android Presentation (Presenters, View Models, Controllers) Desktop Platform-specific code Platform-specific code Platform-specific code #4: Choose what to share, what to write natively
44. 5. Share UI code 4. Choose what to share, what to write natively
45. https://developer.android.com/jetpack/compose #5: Share UI code
46. https://jb.gg/compose #5: Share UI code
47. State of platforms Android iOS Desktop Wasm Compose Multiplatform Stable Stable Stable Beta #5: Share UI code
48. The story of Instabee https://www.youtube.com/watch?v=YsQ-2lQYQ8M #5: Share UI code
49. Instabee Case Study #5: Share UI code
50. Official Sample - ImageViewer App #5: Share UI code
51. Community Sample - NY Times App https://www.github.com/xxfast/NYTimes-KMP #5: Share UI code
52. Finally, modern desktop development framework! #5: Share UI code
53. 6. Use in new or existing projects 4. Choose what to share, what to write natively 5: Share UI code
54. Existing projects: The example of Wonder by , again https://kotlinlang.org/lp/multiplatform/case-studies/baidu #6: Use in new or existing projects
55. New projects: The story of https://raymondctc.medium.com/adopting-kotlin-multiplatform-mobile-kmm-on-9gag-app-dfe526d9ce04 #6: Use in new or existing projects
56. Tried other technologies https://raymondctc.medium.com/adopting-kotlin-multiplatform-mobile-kmm-on-9gag-app-dfe526d9ce04 • React Native (2016) • Flutter (2020) #6: Use in new or existing projects
57. Settled on Kotlin Multiplatform (2021) https://raymondctc.medium.com/adopting-kotlin-multiplatform-mobile-kmm-on-9gag-app-dfe526d9ce04 • Start from Android • Consume Kotlin Multiplatform project as dependency on iOS #6: Use in new or existing projects
58. 7. Start sharing gradually 5. Share UI code 6. Use in new or existing projects
59. Start small • Constants • Migrate common utilities • Write or migrate business logic #7: Start sharing gradually
60. #7: Start sharing gradually
61. “I want to know I’m not alone in this journey of adoption.”
62. 8. Already used by big companies
63. #8: Already used by big companies
64. #8: Already used by big companies https://www.youtube.com/watch?v=zDRlEp7r5i0 (Scaling, 2023) https://www.youtube.com/watch?v=HSIhkB5bGJs (Navigation, 2025)
66. #8: Already used by big companies https://www.youtube.com/watch?v=OuX5325yq_I
67. #8: Already used by big companies
68. kotl.in/kmp-case-studies #8: Already used by big companies
69. 9. Tooling support 8. Already used by big companies
70. IntelliJ IDEA / Android Studio • Kotlin Multiplatform plugin from JetBrains ◦ Support for writing common and platform-specific code ◦ Support for running Android/iOS/desktop apps from the IDE ◦ New project multiplatform wizard ◦ Preflight checks ◦ Basic Swift support ◦ Runs on Windows* / Linux* / MacOS #9: Tooling support
71. Xcode • De facto standard for iOS development ◦ Development, debugging, configuration tools • Mac required! (Apple requirement) #9: Tooling support
72. 10. Supportive community 8. Already used by big companies 9. Tooling support from JetBrains
73. Kotlinlang Slack Workspace • 72k+ members • Relevant channels: ◦ #multiplatform ◦ #compose-ios • Q&A with JetBrains/Google/other knowledgeable experts #10: Supportive community
74. #10: Supportive community
75. Google Google Touchlab TouchlabHQ Philipp Lackner @plcoding John OʼReilly @joreilly Sebastian Aigner @sebi_io Annyce Davis @brwngrldev Tadeas Kriz TadeasKriz #10: Supportive community Márton Braun @zsmb13
76. Google I/O 2024 announcement
77. Google’s support thus far • Annotations • Collections • DataStore • Lifecycle • ViewModel • Room
78. When to choose KMP over other cross-platform technologies
79. Why Kotlin Multiplatform • Kotlin: most awesome development language ;) • Easily write things natively • Excellent performance: code is compiled to native
80. Previously… • Kotlin Multiplatform ecosystem, tooling still maturing • Not as many learning resources available, but rapidly growing
81. But now… • Kotlin Multiplatform ecosystem, tooling still maturing • Not as many learning resources available, but rapidly growing • https://klibs.io/ and KMP plugin in IntelliJ and Android Studio • Many learning resources available
83. https://developer.android.com/kotlin
85. How to decide • Existing team experience • What kind of app you’ll be building • Don’t make Frankensteins!
86. Perhaps I’ve convinced you to try it, but what’s next?
87. Start small • Constants • A small shared irritation • Some common utilities
88. Work out an experiment plan • Hypothesis: what do we think will happen? • Method: how will we go about our experiment? • Conclusion: how will we analyse our results?
89. Work out an experiment plan • Team roles - who will contribute actively? • Workflow - how do you make, distribute changes? • Coding standards - how to write nice APIs • CI/CD - testing and rolling out • Monitoring production
90. Gain trust, expand the scope • Retrospective - did this really work for us? • Yes - do we want to expand the scope? • No - why?
91. https://www.jetbrains.com/help/kotlin-multiplatform-dev/kotlin-multiplatform-flutter.html
92. https://www.jetbrains.com/help/kotlin-multiplatform-dev/kotlin-multiplatfo https://www.jetbrains.com/help/kotlin-multiplatform-dev/kotlin-multiplatform-react-native.html
93. 10 Reasons - Why you should adopt KMP 1. Avoid duplication 2. Extensive list of supported platforms 3. Kotlin is a loved & trusted language for everyone
94. 10 Reasons - You can adopt it flexibly 4. Choose what to share, what to write natively 5. Share UI code with Compose Multiplatform 6. Use in new or existing projects 7. Start sharing gradually
95. 8. Already used by big companies 9. Tooling from JetBrains 10. Supportive community 10 Reasons - You are not alone
96. Thank you! Stay in touch: pamela.hill@jetbrains.com