[simoncion]

I understand and largely agree with your core points and concerns. I, myself am cautious and suspicious of new and/or unfamiliar software stacks. :)

So, the following disjointed commentary might be entirely superfluous. It also makes no mention of Elixir or Phoenix, as I've not yet used them:

AFAIK, everything shipped in Erlang/OTP has a test suite that you can run and -if you've the time and technical chops- inspect and evaluate for completeness and correctness.

Given that the Erlang community tends to be concerned about safety and reliability, I have substantially more confidence in the correctness of some random Erlang library on Github than of some random JavaScript (or -ye gods- Perl) library. ;)

Given that neither Cowboy nor Ranch appear to make use of any NIFs, I would be fairly confident in their safety in the face of garbage or malicious input.

The erlang-questions mailing list is a good place to ask questions of folks who use Erlang professionally and non-professionally for a wide variety of things. I've heard that the Elixir equivalents are similarly helpful.