Ask HN: Tools of the Trade, 2019 Edition

Almost a decade ago, Joshua Schachter started this thread on HN for discussing hosted useful services: https://news.ycombinator.com/item?id=1769910

When I first started delicious, we had to host most of the services ourselves. CVS, mail, mailing lists, etc etc etc.

These days, lots of that stuff is available as SaaS. What are the tools and services people use instead of hosting their own?

What do we have now in 2019?