Kotlin by JetBrains
@kotlinlang.org
Kotlin is a programming language that makes coding concise, cross-platform, and fun — https://kotlinlang.org/
Video tutorials http://kotl.in/video
News http://kotl.in/news
Community discussions http://kotl.in/slack
Video tutorials http://kotl.in/video
News http://kotl.in/news
Community discussions http://kotl.in/slack
🗳️ Help us make Ktor better!
💬 Tell us what’s working, what’s missing, and what would make Ktor better for you.
Your feedback will help shape the next improvements to the framework, docs, and tools.
👉 Take the survey https://surveys.jetbrains.com/s3/05ddc3ebe003
💬 Tell us what’s working, what’s missing, and what would make Ktor better for you.
Your feedback will help shape the next improvements to the framework, docs, and tools.
👉 Take the survey https://surveys.jetbrains.com/s3/05ddc3ebe003
November 26, 2025 at 11:19 AM
🗳️ Help us make Ktor better!
💬 Tell us what’s working, what’s missing, and what would make Ktor better for you.
Your feedback will help shape the next improvements to the framework, docs, and tools.
👉 Take the survey https://surveys.jetbrains.com/s3/05ddc3ebe003
💬 Tell us what’s working, what’s missing, and what would make Ktor better for you.
Your feedback will help shape the next improvements to the framework, docs, and tools.
👉 Take the survey https://surveys.jetbrains.com/s3/05ddc3ebe003
🖤 Black Friday, but make it Kotlin. 💜
✨ Get 20% off KotlinConf 2026 tickets ✨
The offer is valid through November 30.
🎟️ https://kotl.in/conf26-blfr-bl 🎟️
✨ Get 20% off KotlinConf 2026 tickets ✨
The offer is valid through November 30.
🎟️ https://kotl.in/conf26-blfr-bl 🎟️
November 26, 2025 at 9:00 AM
🖤 Black Friday, but make it Kotlin. 💜
✨ Get 20% off KotlinConf 2026 tickets ✨
The offer is valid through November 30.
🎟️ https://kotl.in/conf26-blfr-bl 🎟️
✨ Get 20% off KotlinConf 2026 tickets ✨
The offer is valid through November 30.
🎟️ https://kotl.in/conf26-blfr-bl 🎟️
Pebble going fully open source is a big win for hardware preservation. ⌚️🔓 But for mobile devs, the real story is in the repo.
The new app is a pure KMP + Compose Multiplatform rewrite.
230k lines (Legacy Java/ObjC) ➡️ 37k lines (Kotlin)
Shipped in 6 months with just 2 devs 🔥
The new app is a pure KMP + Compose Multiplatform rewrite.
230k lines (Legacy Java/ObjC) ➡️ 37k lines (Kotlin)
Shipped in 6 months with just 2 devs 🔥
Good news! We open sourced the Pebble mobile app today -> github.com/coredevices/mobileapp Now all the software that powers your new Pebble is 100% open source. Read the full scoop on my blog ericmigi.com/blog/pebble-...
GitHub - coredevices/mobileapp
Contribute to coredevices/mobileapp development by creating an account on GitHub.
github.com
November 25, 2025 at 6:00 PM
Pebble going fully open source is a big win for hardware preservation. ⌚️🔓 But for mobile devs, the real story is in the repo.
The new app is a pure KMP + Compose Multiplatform rewrite.
230k lines (Legacy Java/ObjC) ➡️ 37k lines (Kotlin)
Shipped in 6 months with just 2 devs 🔥
The new app is a pure KMP + Compose Multiplatform rewrite.
230k lines (Legacy Java/ObjC) ➡️ 37k lines (Kotlin)
Shipped in 6 months with just 2 devs 🔥
🤔 Curious about Kotlin but worried about rewriting your Java code?
No need – Kotlin and Java work seamlessly in the same Spring project.
Start with a single service and expand from there.
Check out our updated tutorial 👇 https://kotl.in/rzdau2
No need – Kotlin and Java work seamlessly in the same Spring project.
Start with a single service and expand from there.
Check out our updated tutorial 👇 https://kotl.in/rzdau2
Adding Kotlin to a Java project – tutorial | Kotlin
kotl.in
November 25, 2025 at 4:50 PM
🤔 Curious about Kotlin but worried about rewriting your Java code?
No need – Kotlin and Java work seamlessly in the same Spring project.
Start with a single service and expand from there.
Check out our updated tutorial 👇 https://kotl.in/rzdau2
No need – Kotlin and Java work seamlessly in the same Spring project.
Start with a single service and expand from there.
Check out our updated tutorial 👇 https://kotl.in/rzdau2
Week 3 of #KMPLevelUp is live! 🚀 We’ve curated the definitive KMP Watchlist. See how:
🦉 Duolingo ships to 40M+ users
🍔 McDonald’s shares navigation logic
⚡️ Meetup made their iOS app faster with KMP
Get the playlist & register for the expert webinar ➡️ jb.gg/vbl7v4
🦉 Duolingo ships to 40M+ users
🍔 McDonald’s shares navigation logic
⚡️ Meetup made their iOS app faster with KMP
Get the playlist & register for the expert webinar ➡️ jb.gg/vbl7v4
November 24, 2025 at 5:04 PM
Week 3 of #KMPLevelUp is live! 🚀 We’ve curated the definitive KMP Watchlist. See how:
🦉 Duolingo ships to 40M+ users
🍔 McDonald’s shares navigation logic
⚡️ Meetup made their iOS app faster with KMP
Get the playlist & register for the expert webinar ➡️ jb.gg/vbl7v4
🦉 Duolingo ships to 40M+ users
🍔 McDonald’s shares navigation logic
⚡️ Meetup made their iOS app faster with KMP
Get the playlist & register for the expert webinar ➡️ jb.gg/vbl7v4
Kotlin samples are now part of the official Spring tutorials! 🚀
Check out the Spring WebFlux guide to build a RESTful web service, and switch easily between Java and Kotlin examples ⬇️
https://spring.io/guides/gs/reactive-rest-service
Check out the Spring WebFlux guide to build a RESTful web service, and switch easily between Java and Kotlin examples ⬇️
https://spring.io/guides/gs/reactive-rest-service
Getting Started | Building a Reactive RESTful Web Service
Learn how to create a RESTful web service with Reactive Spring and consume it with WebClient.
spring.io
November 24, 2025 at 10:16 AM
Kotlin samples are now part of the official Spring tutorials! 🚀
Check out the Spring WebFlux guide to build a RESTful web service, and switch easily between Java and Kotlin examples ⬇️
https://spring.io/guides/gs/reactive-rest-service
Check out the Spring WebFlux guide to build a RESTful web service, and switch easily between Java and Kotlin examples ⬇️
https://spring.io/guides/gs/reactive-rest-service
See you at KotlinConf 2026! 😉
You thought last year was cool?
Wait until you see what’s coming to KotlinConf’26! 🔥
👉 https://kotl.in/conf2026-x 👈
Wait until you see what’s coming to KotlinConf’26! 🔥
👉 https://kotl.in/conf2026-x 👈
November 24, 2025 at 6:06 AM
See you at KotlinConf 2026! 😉
📹 Registration for our #KMPLevelUp career webinar is now open! Get your questions ready for legends like Jake Wharton, Zac Sweers, and other Android experts.
And ICYMI, the 5-hour CMP crash course is the perfect weekend project.
Register & watch here: jb.gg/vbl7v4
And ICYMI, the 5-hour CMP crash course is the perfect weekend project.
Register & watch here: jb.gg/vbl7v4
November 21, 2025 at 5:12 PM
📹 Registration for our #KMPLevelUp career webinar is now open! Get your questions ready for legends like Jake Wharton, Zac Sweers, and other Android experts.
And ICYMI, the 5-hour CMP crash course is the perfect weekend project.
Register & watch here: jb.gg/vbl7v4
And ICYMI, the 5-hour CMP crash course is the perfect weekend project.
Register & watch here: jb.gg/vbl7v4
Spring Framework 7.0 has been released, bringing exciting updates for Kotlin users:
🟣 Kotlin 2.2 as the new baseline
🟣 Improved kotlinx.serialization support
🟣 Better Kotlin integration with JSpecify
🟣 Programmatic bean registration DSL
Read more ⬇️ kotl.in/evnyly
🟣 Kotlin 2.2 as the new baseline
🟣 Improved kotlinx.serialization support
🟣 Better Kotlin integration with JSpecify
🟣 Programmatic bean registration DSL
Read more ⬇️ kotl.in/evnyly
Spring Framework 7.0 Release Notes
Spring Framework. Contribute to spring-projects/spring-framework development by creating an account on GitHub.
kotl.in
November 21, 2025 at 4:10 PM
Spring Framework 7.0 has been released, bringing exciting updates for Kotlin users:
🟣 Kotlin 2.2 as the new baseline
🟣 Improved kotlinx.serialization support
🟣 Better Kotlin integration with JSpecify
🟣 Programmatic bean registration DSL
Read more ⬇️ kotl.in/evnyly
🟣 Kotlin 2.2 as the new baseline
🟣 Improved kotlinx.serialization support
🟣 Better Kotlin integration with JSpecify
🟣 Programmatic bean registration DSL
Read more ⬇️ kotl.in/evnyly
📢 Help us improve Kotlin docs!
Share your insights on Kotlin’s documentation to help us enhance your developer experience.
➡️ You'll need a Chromium-based desktop browser to take part in the study. Check if you qualify to participate in our research: https://surveys.jetbrains.com/s3/kotlin-docs-t
Share your insights on Kotlin’s documentation to help us enhance your developer experience.
➡️ You'll need a Chromium-based desktop browser to take part in the study. Check if you qualify to participate in our research: https://surveys.jetbrains.com/s3/kotlin-docs-t
November 20, 2025 at 2:09 PM
📢 Help us improve Kotlin docs!
Share your insights on Kotlin’s documentation to help us enhance your developer experience.
➡️ You'll need a Chromium-based desktop browser to take part in the study. Check if you qualify to participate in our research: https://surveys.jetbrains.com/s3/kotlin-docs-t
Share your insights on Kotlin’s documentation to help us enhance your developer experience.
➡️ You'll need a Chromium-based desktop browser to take part in the study. Check if you qualify to participate in our research: https://surveys.jetbrains.com/s3/kotlin-docs-t
November 19, 2025 at 5:37 AM
🤖 Ever wondered how AI agents work and why Kotlin is perfect for building them?
In the new Talking Kotlin episode, @sebi.io and @zsmb.co chat with @vadim-briliantov.bsky.social, Technical Lead for Koog, JetBrains’ agentic framework for building AI agents in Kotlin.
🎧 https://kotl.in/dvygzb
In the new Talking Kotlin episode, @sebi.io and @zsmb.co chat with @vadim-briliantov.bsky.social, Technical Lead for Koog, JetBrains’ agentic framework for building AI agents in Kotlin.
🎧 https://kotl.in/dvygzb
Building AI Agents With Koog | Talking Kotlin 142
YouTube video by Kotlin by JetBrains
youtu.be
November 18, 2025 at 1:51 PM
🤖 Ever wondered how AI agents work and why Kotlin is perfect for building them?
In the new Talking Kotlin episode, @sebi.io and @zsmb.co chat with @vadim-briliantov.bsky.social, Technical Lead for Koog, JetBrains’ agentic framework for building AI agents in Kotlin.
🎧 https://kotl.in/dvygzb
In the new Talking Kotlin episode, @sebi.io and @zsmb.co chat with @vadim-briliantov.bsky.social, Technical Lead for Koog, JetBrains’ agentic framework for building AI agents in Kotlin.
🎧 https://kotl.in/dvygzb
Ready for a deep dive into Compose Multiplatform? 🚀
For Week 2 of #KMPLevelUp, we've partnered with
Philipp Lackner to bring you a FREE 5-hour crash course.
Want to go even deeper? Find the 30% discount for his premium course on our learning hub.
Get both here ➡️ jb.gg/vbl7v4
For Week 2 of #KMPLevelUp, we've partnered with
Philipp Lackner to bring you a FREE 5-hour crash course.
Want to go even deeper? Find the 30% discount for his premium course on our learning hub.
Get both here ➡️ jb.gg/vbl7v4
November 17, 2025 at 4:59 PM
Ready for a deep dive into Compose Multiplatform? 🚀
For Week 2 of #KMPLevelUp, we've partnered with
Philipp Lackner to bring you a FREE 5-hour crash course.
Want to go even deeper? Find the 30% discount for his premium course on our learning hub.
Get both here ➡️ jb.gg/vbl7v4
For Week 2 of #KMPLevelUp, we've partnered with
Philipp Lackner to bring you a FREE 5-hour crash course.
Want to go even deeper? Find the 30% discount for his premium course on our learning hub.
Get both here ➡️ jb.gg/vbl7v4
⚡ The Kotlin Power-assert is now available for 🪶 Maven!
The plugin makes debugging easier with detailed failure messages and no extra libs needed. Enable it in the section of `kotlin-maven-plugin` in your `pom.xml`.
Read more in the docs 👇 https://kotl.in/wtpugg
The plugin makes debugging easier with detailed failure messages and no extra libs needed. Enable it in the
Read more in the docs 👇 https://kotl.in/wtpugg
Power-assert compiler plugin | Kotlin
kotl.in
November 14, 2025 at 4:45 PM
⚡ The Kotlin Power-assert is now available for 🪶 Maven!
The plugin makes debugging easier with detailed failure messages and no extra libs needed. Enable it in the section of `kotlin-maven-plugin` in your `pom.xml`.
Read more in the docs 👇 https://kotl.in/wtpugg
The plugin makes debugging easier with detailed failure messages and no extra libs needed. Enable it in the
Read more in the docs 👇 https://kotl.in/wtpugg
Not sure where to start with Kotlin Multiplatform and Compose Multiplatform? Here’s your roadmap📍
Week 1 of #KMPLevelUp drops the Course Matrix with:
📚 best learning paths
🎯 clear skill outcomes
🤝 picks from our Dev Advocates
Start your journey: jb.gg/vbl7v4
Week 1 of #KMPLevelUp drops the Course Matrix with:
📚 best learning paths
🎯 clear skill outcomes
🤝 picks from our Dev Advocates
Start your journey: jb.gg/vbl7v4
November 13, 2025 at 2:51 PM
Not sure where to start with Kotlin Multiplatform and Compose Multiplatform? Here’s your roadmap📍
Week 1 of #KMPLevelUp drops the Course Matrix with:
📚 best learning paths
🎯 clear skill outcomes
🤝 picks from our Dev Advocates
Start your journey: jb.gg/vbl7v4
Week 1 of #KMPLevelUp drops the Course Matrix with:
📚 best learning paths
🎯 clear skill outcomes
🤝 picks from our Dev Advocates
Start your journey: jb.gg/vbl7v4
🖼️ Animation tuning as an art form? At KotlinConf25, @nicole-terc.bsky.social showed us how to master AnimationSpec for custom animations.
Catch the full session here:
https://youtu.be/clDGqPfaIto?si=Fud8Tagdk8ZE2bPM
Catch the full session here:
https://youtu.be/clDGqPfaIto?si=Fud8Tagdk8ZE2bPM
November 11, 2025 at 2:16 PM
🖼️ Animation tuning as an art form? At KotlinConf25, @nicole-terc.bsky.social showed us how to master AnimationSpec for custom animations.
Catch the full session here:
https://youtu.be/clDGqPfaIto?si=Fud8Tagdk8ZE2bPM
Catch the full session here:
https://youtu.be/clDGqPfaIto?si=Fud8Tagdk8ZE2bPM
We’re getting closer to Exposed 1.0.0! 🎯
In RC-3, we focused on polishing and fixing bugs in previously delivered features (like R2DBC support and cleaner imports), and on updating and streamlining transaction management.
Give it a try and share your feedback before the release!
kotl.in/vow8yv
In RC-3, we focused on polishing and fixing bugs in previously delivered features (like R2DBC support and cleaner imports), and on updating and streamlining transaction management.
Give it a try and share your feedback before the release!
kotl.in/vow8yv
Release 1.0.0-rc-3 · JetBrains/Exposed
Change log
New Contributors
@nicktelford made their first contribution in #2616
@IlyaPechuro made their first contribution in #2641
kotl.in
November 11, 2025 at 12:39 PM
We’re getting closer to Exposed 1.0.0! 🎯
In RC-3, we focused on polishing and fixing bugs in previously delivered features (like R2DBC support and cleaner imports), and on updating and streamlining transaction management.
Give it a try and share your feedback before the release!
kotl.in/vow8yv
In RC-3, we focused on polishing and fixing bugs in previously delivered features (like R2DBC support and cleaner imports), and on updating and streamlining transaction management.
Give it a try and share your feedback before the release!
kotl.in/vow8yv
📣 The KotlinConf’26 Call for Papers closes soon – you’ve got just three weeks left to submit your idea! We’d love to hear your Kotlin story. sessionize.com/kotlinconf-2...
November 11, 2025 at 8:13 AM
📣 The KotlinConf’26 Call for Papers closes soon – you’ve got just three weeks left to submit your idea! We’d love to hear your Kotlin story. sessionize.com/kotlinconf-2...
Are you for Kotlin 🏝️ or Python 🐍 ?
Team Kotlin → tap like 💜
Team Python → hit repost 🔁
Everyone → read how Python compares to Kotlin and why more teams are switching their backends to Kotlin in this article by @marcinmoskala.bsky.social kotl.in/z44li1
Team Kotlin → tap like 💜
Team Python → hit repost 🔁
Everyone → read how Python compares to Kotlin and why more teams are switching their backends to Kotlin in this article by @marcinmoskala.bsky.social kotl.in/z44li1
From Python to Kotlin: A Transition Worth Making | The Kotlin Blog
Discover why more teams are moving their backend projects to Kotlin for better safety, and scalability in this article by Marcin Moskała.
kotl.in
November 10, 2025 at 7:28 PM
Are you for Kotlin 🏝️ or Python 🐍 ?
Team Kotlin → tap like 💜
Team Python → hit repost 🔁
Everyone → read how Python compares to Kotlin and why more teams are switching their backends to Kotlin in this article by @marcinmoskala.bsky.social kotl.in/z44li1
Team Kotlin → tap like 💜
Team Python → hit repost 🔁
Everyone → read how Python compares to Kotlin and why more teams are switching their backends to Kotlin in this article by @marcinmoskala.bsky.social kotl.in/z44li1
📦 Library publication is much easier in Kotlin 2.2.20!
New Gradle tasks help generate key pairs, upload public keys, and verify everything locally before publishing to Maven Central.
👉 Learn more: https://kotl.in/libpb
New Gradle tasks help generate key pairs, upload public keys, and verify everything locally before publishing to Maven Central.
👉 Learn more: https://kotl.in/libpb
November 10, 2025 at 4:50 PM
📦 Library publication is much easier in Kotlin 2.2.20!
New Gradle tasks help generate key pairs, upload public keys, and verify everything locally before publishing to Maven Central.
👉 Learn more: https://kotl.in/libpb
New Gradle tasks help generate key pairs, upload public keys, and verify everything locally before publishing to Maven Central.
👉 Learn more: https://kotl.in/libpb
Hey Android devs! Planning your next career move for 2026? Go beyond a single platform.
We’ve launched #KMPLevelUp — a free 4-week journey to master KMP with curated courses, expert content, and a live webinar. Time to ship your Kotlin skills to iOS & web: jb.gg/vbl7v4
We’ve launched #KMPLevelUp — a free 4-week journey to master KMP with curated courses, expert content, and a live webinar. Time to ship your Kotlin skills to iOS & web: jb.gg/vbl7v4
Level Up with Kotlin Multiplatform | JetBrains Learning Journey
Master Kotlin Multiplatform before 2026! Join JetBrains’ 4-week KMP learning journey with expert courses, talks, and career insights.
jb.gg
November 10, 2025 at 10:46 AM
Hey Android devs! Planning your next career move for 2026? Go beyond a single platform.
We’ve launched #KMPLevelUp — a free 4-week journey to master KMP with curated courses, expert content, and a live webinar. Time to ship your Kotlin skills to iOS & web: jb.gg/vbl7v4
We’ve launched #KMPLevelUp — a free 4-week journey to master KMP with curated courses, expert content, and a live webinar. Time to ship your Kotlin skills to iOS & web: jb.gg/vbl7v4
We’ve recently released Compose Multiplatform 1.10.0-beta01! 🎉
Highlights of this EAP feature release include:
🧩 Unified @Preview annotation
🧭 Support for Navigation 3
🔥 Bundled Compose Hot Reload
What’s new: https://kotl.in/qb7gxf 👈
GitHub: https://kotl.in/kevvbf 👈
Highlights of this EAP feature release include:
🧩 Unified @Preview annotation
🧭 Support for Navigation 3
🔥 Bundled Compose Hot Reload
What’s new: https://kotl.in/qb7gxf 👈
GitHub: https://kotl.in/kevvbf 👈
What's new in Compose Multiplatform 1.10.0-beta01 | Kotlin Multiplatform
kotl.in
November 8, 2025 at 11:55 AM
We’ve recently released Compose Multiplatform 1.10.0-beta01! 🎉
Highlights of this EAP feature release include:
🧩 Unified @Preview annotation
🧭 Support for Navigation 3
🔥 Bundled Compose Hot Reload
What’s new: https://kotl.in/qb7gxf 👈
GitHub: https://kotl.in/kevvbf 👈
Highlights of this EAP feature release include:
🧩 Unified @Preview annotation
🧭 Support for Navigation 3
🔥 Bundled Compose Hot Reload
What’s new: https://kotl.in/qb7gxf 👈
GitHub: https://kotl.in/kevvbf 👈
⚙️ Concurrent programming in Kotlin just got safer!
The @jetbrains.com Research team developed LitmusKt, a new testing tool for Kotlin’s multiplatform concurrency, and it’s now part of Kotlin’s CI pipeline.
🔗 Learn more: https://kotl.in/eqo4vz
The @jetbrains.com Research team developed LitmusKt, a new testing tool for Kotlin’s multiplatform concurrency, and it’s now part of Kotlin’s CI pipeline.
🔗 Learn more: https://kotl.in/eqo4vz
Finding Order in the Mayhem: A Novel Concurrency Testing Tool that Improved the Kotlin Compiler | The Research Blog
At JetBrains Research we built LitmusKt — a novel concurrency testing tool for Kotlin’s unique mix of JVM, Native, and JavaScript backends.
blog.jetbrains.com
November 7, 2025 at 12:45 PM
⚙️ Concurrent programming in Kotlin just got safer!
The @jetbrains.com Research team developed LitmusKt, a new testing tool for Kotlin’s multiplatform concurrency, and it’s now part of Kotlin’s CI pipeline.
🔗 Learn more: https://kotl.in/eqo4vz
The @jetbrains.com Research team developed LitmusKt, a new testing tool for Kotlin’s multiplatform concurrency, and it’s now part of Kotlin’s CI pipeline.
🔗 Learn more: https://kotl.in/eqo4vz
🎉 Ktor 3.3.2 is here! Explore the changelog to learn more.
kotl.in/nf86gx
kotl.in/nf86gx
WhatsNew 3.3
Kotlin Server and Client Framework for microservices, HTTP APIs, and RESTful services
kotl.in
November 7, 2025 at 10:21 AM
🎉 Ktor 3.3.2 is here! Explore the changelog to learn more.
kotl.in/nf86gx
kotl.in/nf86gx
📣 Calling all Ktor users! We’d love your input! Take our annual survey and share your thoughts, challenges, and ideas to help us make the framework even better.
Your feedback shapes the future of Ktor 🚀
Take the survey 👉 surveys.jetbrains.com/s3/05ddc3ebe...
Your feedback shapes the future of Ktor 🚀
Take the survey 👉 surveys.jetbrains.com/s3/05ddc3ebe...
November 6, 2025 at 9:15 AM
📣 Calling all Ktor users! We’d love your input! Take our annual survey and share your thoughts, challenges, and ideas to help us make the framework even better.
Your feedback shapes the future of Ktor 🚀
Take the survey 👉 surveys.jetbrains.com/s3/05ddc3ebe...
Your feedback shapes the future of Ktor 🚀
Take the survey 👉 surveys.jetbrains.com/s3/05ddc3ebe...