Python Django PostgreSQL Bootstrap jQuery
Healthchecks.io is a SaaS cron monitoring service. I needed a tool to monitor my cron jobs. I was not happy with the existing options, so I wrote one. The initial goal was to get to a MVP state, and use it myself. The followup goals were to add functionality and polish the user interface, while keeping the UI and the under the hood stuff as simple and clean as possible.
Python and DJango were obvious choices as I was already familiar with them, and knew that many of Django's built-in features would come handy in this project: ORM, testing infrastructure, user authentication, templates, form handling.
On the UI side, instead of doing the trendy "React JS app talking to API endpoints" thing, I went with the traditional HTML forms, and full page reloads. I was aiming for the max simplicity. Paraphrasing Kevin from The Office, why waste time write lot JS when form submit do trick. The frontend does however use some JS, for example, to support live-updating dashboards.
The backend is also aiming for max simplicity, and I've tried to keep the number of components to the minimum. For example, a message broker or a key-value store could be handy, but so far I'm getting away with storing everything in the Postgres database.
The deployment and hosting setup is also rather primitive by today's standards. uWSGI runs the Django app, with a nginx reverse proxy in front. uWSGI and nginx are run as systemd services on bare metal servers. Traffic is proxied through Cloudflare Load Balancer, which allows for relatively easy rolling code upgrades. I use Fabric for automating server maintenance. I did use Ansible for a while but moved back to Fabric: my Ansible playbooks were slower, and I could not get used to mixing YAML and Jinja templating.
Healthchecks.io tech decisions in one word: KISS. Use boring tools that get the job done.