Pathwright

App servers, celery VMs, and a number of internal supportting systems run on EC2. Amazon EC2

Storage of course assets, some logos, encoded media, attachments, assignment submissions, and much more. Amazon S3

Our backend is a large Django app. We use lots of django-rest-framework to interface with the client side. Django

While we initially started off running our own Postgres cluster, we evaluated RDS and found it to be an excellent fit for us.

The failovers, manual scaling, replication, Postgres upgrades, and pretty much everything else has been super smooth and reliable.

We'll probably need something a little more complex in the future, but RDS performs admirably for now. Amazon RDS

We started off with AWS SES, but found it to be lacking in diagnostics and reporting. Mandrill is a quantum leap forward in this regard. Has some other really neat features carried over from MailChimp (templating). Mandrill

We started with PayPal initially, but Stripe appeared and made our lives much easier. They are now our primary payment service. Stripe

Activity feeds, event logging, business analytics. Keen has been incredibly valuable in its ease of use. Keen

Parked in front of an nginx instance that serves all of our static assets. Performance and reliability have been excellent, and the header pass-through rules are wonderful. Price is affordable, as well. Amazon CloudFront

Server and application performance monitoring, alerting, and page/background task tuning. New Relic

All Pathwright repos are stored on Github. Some private, and a handful of open source projects. GitHub