How can I tell whether a web app was built using Angular (or other technologies)?

Question

How can I tell whether a (Drupal 7) web app was built using Angular by looking at the page source, and not having to ask the developers?

Answer 1

Try

https://builtwith.com/

This is the website that currently gives you the most detailed information about what technologies a site uses. They will let you do 5 free lookups a day.

https://wappalyzer.com/

is a good one too, and serve as a complement to builtwith. I don't think there is a limit of lookups, but the results are less detailed.

Those two used together may give you more insight.