We polled a total of 100 users on javalin.io. To filter out non-users the survey link was only shown to users who had performed 5 page loads. That wasn’t enough though, as it turned out a third of respondents were not actually using Javalin yet. These responses have been filtered out.

General

Q: What role best describes you?

Software engineer / developer
Tech lead / manager
Hobbyist programmer
Student

No real suprises here. Most of our users are Software Engineers / Developers. The number of tech leads and managers is perhaps a bit higher than expected, but not by a lot.

Q: What are you using Javalin for?

REST APIs
WebSockets
Websites
Maven Server

As expected, most people use Javalin to create REST APIs. A surprisingly high number of people also use Javalin for creating websites, and there was one person using it for a local Maven Server (!).

Q: What language are you using Javalin with?

Java
Kotlin
Other

When Javalin was created, the goal was to achieve a great developer experience in both Java and Kotlin. This seems to have been a good goal, since the split is about equal (it was possible to select both languages for this answer).

Q: Are you using Javalin in production?

Yes
Soon
No

Most users are either running in production right now, or will be soon. Javalin appears to be a popular choice for startups and new projects, so this makes sense.

Production usage

Only the users who replied yes to Are you using Javalin in production were able to answer the next three questions.

Q: How many users does your application have?

Less than 1k per day
1k - 10k per day
10k - 100k per day
100k - 1m per day
More than 1m per day

Most Javalin apps appear to be fairly low traffic. Even one million requests per day is only 12 requests per second, which is a tiny fraction of what Javalin can handle. Javalin adds a very small overhead to Jetty (less than 5%), and can easily serve thousands of requests per second.

Q: Approximately how big is your application?

Less than 1k lines of code
Between 1k and 10k lines of code
More than 10k lines of code

No surprises here. Small codebases are great!

Q: How many people are working on your application?

1 - 2 people
2 - 5 people
More than 5 people

Conclusion

Hopefully this survey provides some insight. We’ll run it again next year with the same questions and see if anything changes. Thanks for reading!