Who is using Java (JVM) in startups?

I am using Kotlin with Quarkus for my healthtech startup (founded last year), mainly because it just works. JVM is a very optimised piece of software, and it can handle almost anything you throw at it. And I like writing Kotlin, which I think is more expressive compared to something like Go, while being less verbose than Java. Contrary to popular opinion of not touching ORMs, I use Hibernate, and it might be the best ORM available. None other ORM library comes close - but that's just my opinion. Sure, I can handwrite SQL queries, but as a startup, my data schema is always changing and I don't want to spend my time updating those raw queries when Hibernate can do it for me. I use it at my day job as well.

I worked for a startup that used Kotlin. The language itself is not that bad (if you ignore the engineers that want to use every single time all the features the language has to offer), but the ecosystem was awful. We were using Gradle, and Spring Boot: just too much magic for my taste. Gradle itself is a beast I never fully understood, and I don't comfortable working with such tools (the Gradle userguide has over 1000 pages https://docs.gradle.org/current/userguide/userguide.pdf)

On the other hand, Go is a breath of fresh air; the tooling is simple and one can actually learn them in no time. There's less magic, and so a bit more of repetition, but I can live with that.

I don't see the advantage of having the JVM to be honest. I just don't see why it would be needed in 2025 (the "Write once, run anywhere" is not relevant anymore).

I think as long as Java has a massive backing, more people are going to want to use Java and create a self-perpetuating cycle. Even if the frontend tech changes, like Java to Kotlin to Scala, etc, the backend will always be the same. The JVM is an amazing piece of software with a massive community behind it, and I dont see that changing anytime soon.

The startup that I work at had started as a project a contracting company had taken on, and they had chosen Java Spring Boot to handle their REST API backend back in 2020.

Although probably not the decision I would have made, it's actually a pretty nice ecosystem that has scaled really well and been fairly easy to work with. Java 21 has _most_ of the QoL features that I like (I'd still really like a `?.` null operator that I can chain together) as well as the ability to reach for JPQL/SQL easily with JpaRepositories when performance is needed.

It's been fairly easy to onboard devs to the project even if they have not had previous experience with Java, and has maintained relatively decent code quality over the last 4 years.

I'm currently working on a LLM project for them that is being completed in Python, however, due to most of the tools being python-first and most of the LLM talent being python-first.

I've done some work for a startup that uses Java as well as some other Java related technologies you might consider outdated. Their founder is an older guy and wrote the MVP himself. But hey - it all works and does the job quite well.

You can create an API and query databases with just about anything.

JVM is a heavy old begemoth. That is the core reason behind it not being popular among startups.

This doesn't mean it's bad (sometimes you need big gun, something mature and advanced), just out of many startups' immediate scope.