There are. Here is a copy of my notes on the subject:

https://gist.github.com/brson/9422a92791062ac52d9e08f0ba7d48...

Sorry it's not more organized and detailed.

just a sample: dropbox, cloudflare, canonical, sentry, atlassian, npm, ibm, xero

https://www.rust-lang.org/production

https://www.rust-lang.org/production/users

I know Discord is migrating a lot of their stuff from Go to Rust. Not sure how major you consider Discord.

The Mullvad VPN app is written in Rust.

a very small part of ChromeOS is written in Rust...(mainly in Linux apps support, aka "crostini", https://chromium.googlesource.com/chromiumos/platform2/+/mas... for instance as well as other bits).

I'm compiling a list of companies using Rust (https://github.com/omarabid/rust-companies). Probably the next step is to rank companies by how much they are really using Rust and linking products that are using it.

Some: https://www.jonathanturner.org/2018/07/snapshot-of-rust-popu...

As far as "using it in a substantial portion of their product", dunno.

Hardly major, but our[0] entire stack except the frontend is Rust.

[0] https://dtmf.io/