Backblaze engineer here -> we absolutely DO NOT use a JVM on the client running on laptops. We love Java and use it in the datacenter on every web server and every pod. The reason we don't use it on the client running on laptops is twofold:

1) Java doesn't deploy super smoothly - The initial download might be 30 MBytes to include the JVM instead of 1 or 2 MBytes for a 'C' executable. Also, you have to keep updating the JVM separately, etc. It's friction to customers.

2) Java is hard to make look "native". Macintosh/Apple customers especially are sensitive to the look and feel of applications and like them to feel extremely "native".

Their web page disagress with you:

"No Java Software Java is responsible for 91% of security attacks. Backblaze's code is native to Mac and PC and doesn't use Java."*

It even has a big logo with Java logo crossed out.

I'm pretty sure their clients are all native.