Visa for visitor from Macedonia

[purplepolarbear]

I have been working remotely with a software developer for a while. He is very good at his job, and I'm considering inviting him over to the UK as I would like to meet him face to face, maybe work on a couple of things together while he is here and reward him for his efforts and encourage him to continue.

He lives in Macedonia (which is not in the EU). What hurdles is he likely to encounter getting a visa to enter the UK, and is the process likely to be expensive and time consuming?