Some e-mail communication needs a independent provider, for these purposes we use SES.
All incoming requests pass through our high redundancy load balanced nginx instances, no matter if it's static resources for the websites, API calls via uwsgi or TCP stream-based services.
Python is (together with C++) the main language of GatewayAPI.com, we use it for the bulk of our APIs.
Our status page is run by statuspage.io.
We use nagios based OpsView to monitor our server farm and keep everything running smoothly.
All data not yet commited to PostgreSQL, lives in multiple redis instances. We are heavy users of lua in redis to enable custom queue behavior.
The most latency sensitive parts are written in C++. Due to our interconnected services architecture, we use either Python or C++ for each service, with the performance critical parts being C++14.
Almost all company communication happens in slack, it's the beating heart of OnlineCity.
We are a heavy user of Github, including pull requests for peer review.
Travis builds, tests and ultimately deploys our websites and APIs.
Our platform is based on interconnected services with a custom RPC protocol based on ZeroMQ and inspired by ZeroMQs LPP/MDP protocols.
Sentry is integrated into both the frontend UI and the backend APIs. Soon C++ too!
Chatlio enables us to communicate with customers via slack, right on our websites.
Our markup is HBS
We build our SASS-based CSS with Compass
We use a bootstrap based theme for our self service webapp.
PostgreSQL is our datastore, used for long term storage and analytics. But not active data, such as messages enroute.
Flask drives our APIs, both the Website APIs and the majority of the REST Messaging APIs
Code Coverage is an important metric for us as we aim to deliver regular improvements to our platform.
We use CF for DNS hosting, since their AnyCast DNS provides the best latency in the business, and they support DNSSEC + IPv6.
We don't use the CDN or website optimizations.