RRrrdharan·Sep 25, 2018
Dropbox uses Go (https://github.com/dropbox/godropbox), Rust (e.g. https://github.com/dropbox/rust-brotli) and Python on the server-side, and both Rust (https://github.com/dropbox/finderinfo-rust) and Python on the client-side.
As other commenters have noted, a lot of their Python use for large scale systems was an artifact of history and available choices at the time, but from my experience during my time there and following as an outside observer since leaving, they seem to make reasonable infrastructure and language decisions for their core product.
In How we rolled out one of the largest Python 3 migrations