Our go to scripting language. If we need it done right now, we do it with python.
Postman is in our opinion the best and simplest way to test/use an api. Building and testing requests is a breeze.
Postgres is our database of choice because of it's power and reliability. It is the storage backend of nearly all of our web applications.
We use nginx to serve static files and to proxy requests to other services. We use it because of it's remarkable performance and simple configuration.
We use Ubuntu 16.04 LTS on all our public facing servers because of the ease of use, reliability and availability of packages.