C++ for shared mobile libraries, though the more recent projects are going the way of Rust.

Objective C and Java on clients, some Kotlin.

JVM in other places with Java for services, and Scala for EMR/Spark jobs.

Most of my back end runs through AWS though I moved some services on Azure now (mainly just to learn but it worked fine enough to move it for a couple production environments).

For storage I have my own Postgres instances. Way cheaper than any cloud. If I need regionalization and better redundancy, might move to AWS eventually.

Day to day tools involve Omnigraffle, Omnifocus, and iTerm2. Yes, everything on a MacBook Pro with a 1440p 120hz monitor.