I use Powershell for everyday scripting, text manipulation, simple REST api testing and other tasks. My choice to use Powershell was primarily based on availability. At the time (2010), every company machine I was using or going to use was Windows and guaranteed to have Powershell. Python was an option but not guaranteed to be installed on every machine. The choice was not based on ease of use, flexibility or support.

We’re a new startup so we need to be able to deliver quick changes as we find our product market fit. We’ve also got to ensure that we’re moving money safely, and keeping perfect records. The technologies we’ve chosen mix mature but well maintained frameworks like Django, with modern web-first and api-first front ends like GraphQL, NextJS, and Chakra. We use a little Golang sparingly in our backend to ensure that when we interact with financial services, we do so with statically compiled, strongly typed, and strictly limited and reviewed code.

You can read all about it in our linked blog post.

We have a lot of experience in JavaScript, writing our services in NodeJS allows developers to transition to the back end without any friction, without having to learn a new language. There is also the option to write services in TypeScript, which adds an expressive type layer. The semi-shared ecosystem between front and back end is nice as well, though specifically NodeJS libraries sometimes suffer in quality, compared to other major languages.

As for why we didn't pick the other languages, most of it comes down to "personal preference" and historically grown code bases, but let's do some post-hoc deduction:

Go is a practical choice, reasonably easy to learn, but until we find performance issues with our NodeJS stack, there is simply no reason to switch. The benefits of using NodeJS so far outweigh those of picking Go. This might change in the future.

PHP is a language we're still using in big parts of our system, and are still sometimes writing new code in. Modern PHP has fixed some of its issues, and probably has the fastest development cycle time, but it suffers around modelling complex asynchronous tasks, and (on a personal note) lack of support for writing in a functional style.

We don't use Python, Elixir or Ruby, mostly because of personal preference and for historic reasons.

Rust, though I personally love and use it in my projects, would require us to specifically hire for that, as the learning curve is quite steep. Its web ecosystem is OK by now (see https://www.arewewebyet.org/), but in my opinion, it is still no where near that of the other web languages. In other words, we are not willing to pay the price for playing this innovation card.

Haskell, as with Rust, I personally adore, but is simply too esoteric for us. There are problem domains where it shines, ours is not one of them.