Talking Kotlin

The Kotlin ecosystem is full of powerful tools and frameworks — and in this episode of Talking Kotlin, we’re diving deep into Exposed, JetBrains’ Kotlin SQL library, which recently reached its 1.0 release.Sebastian and Márton sit down with Chantal from the Exposed team to explore what Exposed is, where it came from, and how it helps developers work with databases in a Kotlin-first way. From type-safe SQL DSLs and lightweight DAO support to JDBC, R2DBC, Ktor, Spring Boot, migrations, and future KMP plans — this episode covers the past, present, and future of Exposed.You’ll learn:What makes Exposed different from traditional ORMsHow the DSL and DAO APIs work togetherWhy Exposed 1.0 required a major architecture redesignHow R2DBC support enables non-blocking database accessHow Exposed integrates with Ktor and Spring BootWhat’s coming next: migrations, plugins, DAO improvements, and KMP supportThe surprisingly charming origin story behind the Exposed cuttlefish mascotWhether you’re already using Exposed or just looking for a Kotlin-friendly way to work with SQL databases, this episode is packed with practical insights and behind-the-scenes stories from the team building it.Try Exposed Read the docs Join the discussion on Kotlin Slack Report issues or share feedback on YouTrack

Every time you tap through a subway gate in New York City, you’re using Kotlin Multiplatform! In this episode, we sit down with Paweł Kwieciński from Masabi to explore how they brought a decade-old Java codebase to KMP, powering ticket validation across mobile apps, embedded devices, and backend systems for public transit agencies worldwide.
Resources:
Masabi
J2ObjC (Java to Objective-C translator)
Google Workspace Migration to Kotlin
Large Scale Changes with AI – Uber | Ty Smith
KotlinX DateTime
Ktor (Client & Server)
Burst library (archived)
Java ME (Micro Edition)
Mbed TLS
SQLDelight
Compose Multiplatform
JetBrains AI Assistant & Junie
Hosts:
Sebastian Aigner – Website | Bluesky
Márton Braun – Website | Bluesky
Guest:
Paweł Kwieciński
Timeline:
(0:00) Introduction
(1:12) What is Masabi?
(3:03) How does Kotlin fit into this?
(6:30) System architecture overview
(8:33) Embedded SDK and mobile apps
(10:33) Ticket inspectors and validators
(13:22) Offline operation
(16:29) The KMP decision
(24:42) Evaluating alternatives
(27:21) Planning the migration
(33:28) First lines of Kotlin
(43:45) Translating Java to Kotlin
(53:22) AI-assisted code translation
(56:39) Early AI era challenges
(1:05:01) Testing challenges
(1:08:22) KMP dependencies
(1:11:34) Domain-specific dependencies
(1:16:55) Java ME and C interop
(1:23:22) Backend-client sharing
(1:26:59) Current status
(1:31:48) Future plans: CMP
(1:36:26) Wrap-up

Sebastian and Márton host a special, audio-only episode where they discuss everything that’s new and noteworthy in the Kotlin 2.3 release. They touch on new language features like the unused return value checker and explicit backing fields, previously added features that became stable in this release, new APIs for time and UUID handling in the standard library, and improvements across all Kotlin platforms — from Native to Wasm and JS.
Resources:
What’s new in Kotlin 2.3
KotlinConf
Golden Kodee Community Awards
Hosts:
Sebastian Aigner – Website | Bluesky
Márton Braun – Website | Bluesky
Timeline:
(0:00) Intro
(1:13) Nested type aliases (stable)
(1:46) Data-flow based exhaustiveness checks (stable)
(3:28) Return statements in expression bodies
(4:19) Unused return value checker (experimental)
(12:57) Explicit backing fields (experimental)
(18:51) Context-sensitive resolution (experimental)
(20:11) Clock and Instant in the standard library (stable)
(21:52) UUID v7 support and better parsing
(26:14) Java 25 bytecode
(26:36) Faster Native release builds
(27:45) Swift Export: enums and varargs
(29:08) C and Objective-C library import (beta)
(30:49) Apple target support changes
(32:15) Fully qualified names in Kotlin/Wasm
(34:10) New exception handling for wasmWasi
(35:32) Suspend function export to JS
(37:51) LongArray export to JS
(38:40) Unified companion object access in JS
(41:05) @JsStatic inside interfaces
(41:43) Default exports in JS
(43:45) Compose stacktraces for minified Android apps
(45:23) Breaking changes 🐜
(46:14) Documentation updates
(47:24) KotlinConf, Golden Kodees Awards
(48:11) Wrap-up

Sebastian and Márton talk to Vadim Briliantov, the Technical Lead for Koog: an agentic framework built by JetBrains. We learn about what AI agents are, and why building them in Kotlin with Koog is a great choice. We also discuss all the different ways AI agents can connect to other systems and your existing code, and look at advanced features for agents like custom strategies, model switching, and history compression.
Resources:
JetBrains/koog on GitHub
Koog Documentation
Hosts:
Sebastian Aigner – Website | Bluesky
Márton Braun – Website | Bluesky
Guest:
Vadim Briliantov – LinkedIn | Medium | GitHub | Bluesky | Twitter/X
Timeline:
(0:00) Intro
(1:11) Vadim’s history at JetBrains
(4:21) What’s an AI Agent?
(5:47) Koog!
(7:12) Applications for agents
(12:43) Koog’s building blocks
(15:05) Strategies, feedback loops
(23:55) The Kotlin DSL
(26:12) Persistent state
(29:48) Subgraphs
(32:33) Tools
(39:52) MCP support (and A2A)
(44:01) Entry point and type safety
(49:39) Spring and Ktor support
(51:27) LLM Providers
(53:30) Model switching
(56:02) History and memory
(59:22) Enterprise-ready
(1:02:12) History compression
(1:11:47) Markdown?!
(1:14:37) What’s next?
(1:18:22) Going open-source
(1:20:32) Conclusion

Sebastian and Márton chat with Marcin Moskała about coroutines.
Resources:
Coroutines Mastery course
Coroutines | Kotlin Documentation
kotlinx.coroutines
Taming Asynchronous Beasts | Marcin Moskała
Coroutine Debugging in IntelliJ IDEA | Alexey Merkulov
Lifecycles, Coroutines and Scopes | Alejandro Serrano Mena
Collect Like a Pro | Manuel Vivo
Untangling Coroutine Testing | Márton Braun
JetBrains/lincheck – Concurrent testing framework
#talking-kotlin on Kotlin Slack
Hosts:
Sebastian Aigner – Website | Bluesky
Márton Braun – Website | Bluesky
Guest:
Marcin Moskała – kt.academy
Timeline:
(0:00) Introduction
(1:18) Branding discussion
(3:23) Handling preconceptions
(4:54) What are coroutines?
(7:17) Lightweight threads?
(11:07) Where coroutines live
(13:27) Sequence Builder Example
(17:37) The design of coroutines
(20:52) What Makes Coroutines special vs other languages?
(26:56) Coroutines vs Loom
(34:55) Easy to start, hard to master
(41:07) Common mistakes
(49:33) Flows
(58:52) Thinking about Flows
(1:02:41) Derailing the conversation
(1:03:55) Flows for single values
(1:12:27) Structured concurrency
(1:18:53) The 4 advantages
(1:24:40) Seb tries web dev / The web is broken?!
(1:31:15) collectAsStateWithLifecycle
(1:32:00) Gardening break
(1:36:23) Scopes and contexts
(1:43:22) Testing coroutines
(1:50:29) Lincheck
(1:51:32) Turbine
(1:55:05) Coroutines Mastery course
(2:01:43) Wrap-up