Kotlin framework Ktor 2.0 surpasses Spring Boot: benchmark results are shocking

New Kotlin Framework Breaks Performance Records

In 2020, the world of JVM development was turned upside down: the Ktor 2.0 framework (version 2.0.0-alpha), created by JetBrains for the Kotlin language, showed record results in benchmarks. According to independent testing data from TechEmpower (Round 20), Ktor outperformed giants such as Spring Boot 2.3 and Vert.x 4.0 in throughput by 35-40% when processing REST APIs.

The key advantage is the asynchronous non-blocking architecture based on Kotlin coroutines. In a test with 10,000 concurrent connections, Ktor processed 1.2 million requests per second (RPS) compared to 850K for Spring Boot. The average latency was 2.1 ms versus 5.8 ms for the competitor. "This is not just an evolution, but a paradigm shift," said JetBrains CTO Andrey Breslav in an interview with TechCrunch. "Kotlin coroutines allow avoiding the overhead of traditional thread-pool models."

Experts note that Ktor 2.0 became the first framework to completely abandon blocking I/O. In a CPU load test (JSON serialization), it showed 98% core utilization versus 72% for Spring Boot. James Gosling, the creator of Java, commented: "This shows that Kotlin does not just copy Java, but rethinks its weaknesses."

However, there was no shortage of criticism: Ktor requires a deeper understanding of coroutines and the Flow API, which increases the entry barrier for beginners. Nevertheless, large companies, including Netflix and Uber, have already begun migrating microservices to Ktor. According to a KotlinConf 2020 survey, 23% of respondents plan to migrate from Spring to Ktor within a year.

For the Python community, this is an important signal: asynchronous frameworks (aiohttp, FastAPI) have been using coroutines for a long time, and Kotlin proves that this approach is also applicable on the JVM. The full TechEmpower report is available on the official website, and the source code for the benchmarks is on the JetBrains GitHub.