KotlinConf 2025 has firmly placed server-side Kotlin in the spotlight, and rightly so. Between Spring collaboration, an upgraded ecosystem, performance boosts, AI tooling, and the adoption of the language by big companies, this is Kotlin at its (backend) best. Heres a breakdown of what was announced, whats new, and what you absolutely must check out from the recordings of the server-side talks at KotlinConf 2025.The biggest news was traditionally covered in the keynote and followed up by talks over two days.One of the revelations from the keynote that received many positive reactions was that half of Kotlin users are using the language for backend development. This isnt a sudden shift but something we have observed over the years in the past Kotlin Census and Developer Ecosystem reports.Check out why developers continue to choose Kotlin for the backend in 2025 in the teaser video linked below, in which engineers from five major tech companies share their Kotlin journeys.The full stories will be published soon on the Kotlin YouTube channel.A Strategic Partnership With SpringThe JetBrains and Spring teams announced a strategic partnership. The roadmap highlights include a complete null-safety guarantee for Kotlin and Spring apps, official Kotlincentric Spring tutorials and documentation, enhanced reflection performance using kotlinx.reflect, and evolving configuration DSLs.Two sessions provided a deeper look into the world of Kotlin and Spring and its upcoming directions for development.Rod Johnson, Springs original creator, spoke on why Kotlin with Spring delivers faster development with better maintainability. Spring Framework core committer Sbastien Deleuze presented updates in Spring Boot 4 that further refine Kotlin support, from annotation processing to coroutine integration.Ktor: Built for Modern Scalable BackendsKtor continues to evolve into a powerful, modern framework for scalable applications. The recent update introduced built-in support for dependency injection with coroutine-based lifecycle management, and a new HTMX module for smoother server-driven UI development. Other notable additions include support for suspendable application modules, Unix domain sockets for the CIO engine, and a Gradle version catalog for easier dependency management.Currently, the team is working on the API documentation, starting with OpenAPI support.For those working with Ktor (or planning to), these talks are must-watches: TalkPresenterWhy It MattersSimplifying Full-Stack Kotlin: A Fresh Take With HTMX and KtorAnders SveenChallenge the modern full-stack complexity and see how to build dynamic web apps with Ktor, HTMX, and kotlinx.html without SPA overhead.Coroutines and Structured Concurrency in KtorSimon VergauwenMaster robust and maintainable asynchronous patterns in real-world Ktor services.Event-Driven Analytics: Building Real-Time Dashboards With Apache Flink and KtorViktor GamovLearn how to move beyond REST by using Apache Flink and Ktor to build real-time analytics dashboards with reactive, event-driven architecture.Kotlin and AI with Koog, Mellum, and JunieJetBrains introduced a trio of AI tools designed for Kotlin development, including practical support for server-side tasks.Koog a Kotlin-based framework designed to build and run AI agents entirely in idiomatic Kotlin.Mellum the JetBrains in-house LLM, which is now open-sourced and fine-tuned for code generation and intelligent assistance.Junie the JetBrains AI coding agent integrated in your favorite IDE and able to target complex Kotlin development across server, mobile, and web domains. Its now available in GitHub as part of the Early Access Program. Join the waitlist to try it for free. TalkPresenterWhy It MattersBuilding AI Agents in Kotlin with KoogVadim BriliantovAn overview of AI agents, their building blocks, workflows, and how to build them effectively in Kotlin from the JetBrains AI Agents Platform tech lead.Kotlins Gam[e]bit: LLM-less AI for Board GamesDmitro KuretsDiscover how Kotlin can power AI without relying on large language models.From 0 to h-AI-ro: high-speed track to AI for Kotlin developersUrs PeterThis talk gives you a clear and practical understanding of key terminology, concepts, and frameworks relevant to the Kotlin ecosystem in the world of AIBuilding an Agentic Platform with Kotlin: Powering one of Europes Largest LLM BotPatrick WhelanA look at some of the design decisions of the Arc framework, an open-sourced Kotlin-based AI framework, which will provide you with an understanding of the challenges in building an LLM application at this scaleLangChain4j With QuarkusMax Rydahl Andersen, Konstantin PavlovThe talk explores tools integration, dependencies management, and Kotlins idiomatic features, helping to simplify AI workflows.A New Milestone: Exposed1.0After substantial restructuring, Exposed1.0 (now in Beta) delivers on its promise of a typesafe, expressive, and idiomatic Kotlin SQL library.With added support for full R2DBC, enabling non-blocking database operations through suspending functions and flows, new SQL features, improved onboarding materials, and a new IDE plugin, it removes friction from database operations while enhancing safety and maintainability.Chantale Loncles talk dives into the details of whats new and whats next. Check it out below.Win With Kotlin NotebookRoman Belov, the lead of Kotlin Moonshots projects, shared a fun yet practical example of Kotlin Notebook in action: finding the longest possible sailing route in 24 hours without repeating waypoints. With Kotlin Notebook, even complex logic becomes intuitive and visual. Watch the talk to learn the full story!http4k: Pure Kotlin, Protocol AgnosticThe talk Full Stream Ahead: Breaking Protocol Barriers With http4k showcased a fully functional, coroutine-based approach to server-side development that sidesteps servlets entirely. It emphasized composability, lightweight design, and streaming I/O with functional purity.Other Server-Side-Related Talks TalkPresenterWhy It MattersThats Unpossible A Full-Stack Side Project Webapp (Including a High-Fidelity UI!) All in KotlinDan KimA practical walkthrough of building a fully functional web app entirely in Kotlin, from backend to high-fidelity UI.IoT Development With KotlinErik HellmanA hands-on look at building IoT applications using Kotlin, with key technologies and integration strategies.Taming Asynchronous Beasts: Debugging and Performance Tuning in a Coroutine WorldMarcin MoskaaAn expert-level deep dive into coroutine debugging and performance tuning from the author of Kotlin Coroutines: Deep Dive.Kotlin Multiplatforms Cross-Platform Brilliance at Norways 377-Year-Old National Postal ServiceAnshika KoulA real-world case study of Posten Bring, detailing how the national postal service used Kotlin on all platforms to modernize logistics at scale.Kotlin Clean Architecture for Serverless: Business Logic You Can Take AnywhereElena van EngelenA clean architecture approach to structuring serverless Kotlin apps, focused on portable business logic across cloud providers.From Data to Insights: Building a Bluesky Bot powered by AIRaphael De LioHow to quickly collect, process, and analyze data using Kotlin demonstrated via a Bluesky bot that extracts insights from real-time streams.That wraps up our curated list of backend-focused talks at KotlinConf 2025. Explore them all via the conference website or mobile app, and share your favorites with the community.Kotlins Backend MomentumKotlinConf 2025 made it unmistakably clear: Kotlin continues to thrive in server-side development. Its pragmatic, loved by engineers, and increasingly adopted across infrastructures and domains from Spring and Flink to Kafka and serverless platforms. Much of this progress is powered by exceptional tooling from JetBrains, including intelligent IDE support and new AI integrations.That being said, the biggest engine behind Kotlins evolution is the community: library maintainers, open-source contributors, companies scaling Kotlin in production, and speakers sharing hard-earned lessons. Thank you all very much, we wouldnt be where we are without you!If youre evaluating Kotlin for backend development in 2025, nows the time to give it a serious look. And if youre already building with Kotlin thank you! Youre shaping the future of a language that grows stronger with every contribution.