I used Flask because it's lightweight and I've used it many times before.

I used Redis as a queuing backend because I'm familiar with it, it's fast, and it's well supported with Python libraries.

I used PostgreSQL because it more elegantly handles a lot of existing issues that MySQL has, like storing true UTF-8.

I used jQuery because I live in the early 2000s, and I don't love Javascript.

I used Python because I love Python.

I used MongoDB to store entire JSON API responses from external APIs.

I stored attachments like resumes on Amazon S3 for speed/ease/long-term thinking about scalability.

I used Keen because it was an extension that could be added through Heroku. It was very easy to set up application metrics and dashboards with them.

I forward all e-mails to Mailgun and appreciate being able to access the objects easily as JSON.

I set up text-message alerts to be sent to me when an error was raised on the web application.

Deployed to Heroku. Mostly a choice out of ease and good command line tools.