<https://blog.jetbrains.com/ai/2025/08/koog-0-4-0-...

# announcements

[Alina Dolgikh [JB]]

Koog 0.4.0 is out! It brings practical upgrades for building production-ready agents in Kotlin:

✔️ Full observability with OpenTelemetry support for Langfuse and W&B Weave
✔️ Drop-in Ktor integration
✔️ Native structured output with fallbacks and fixing strategies
✔️ iOS support via Kotlin Multiplatform
✔️ GPT-5 and custom tuning params
✔️ Production-grade retry logic

Learn more: https://kotl.in/koog-0-4-0-release