[kasey_junk]

A caveat to start with, I am not a front-end guy (though i program golang backend infrastructure all day/every day)...but I think the question of whether golang is mature enough for fintech and if golang is a good choice as an early language for you are orthogonal.

In the domains that golang excels in, it is much more mature than its age. Things like security, memory use, serving network daemons etc. it is great. I would be happy to advocate for it in environments that require a "mature" stack.

But if what you want to do, is rapidly take data from a user and put it into a database, over the internet, I'd say it is a pretty bad choice. Especially if you already have rails experience. Rails is purpose built for that use case and it is (from what i hear) good at it.