Upwork is one of the largest freelance marketplace with 12M+ registered freelancers and $1B+ billed annually. It has a broad range of providers, from novice freelancers to 50+ person development teams making millions in revenue per year.
It presents itself as a place where you can easily hire a good coder. However, quick googling reveals many posts about negative client experiences on Upwork.
Don’t be discouraged right away.
Inevitably, such a large overall transaction volume produces quite a few failed projects and people are far more likely to share their bad experiences than good. Just be mindful of the fact that Upwork does have some very bad developers. Nevertheless, I believe that majority of the providers on this system are genuine professionals caring about their reputation.