[aspirin]

In professional contexts as a software developer you will manage just fine with just English. Free time context and true integration to society will require learning Finnish. But you can take your time with that.

I’m a Finn.

[mongol]

I think the challenge with going freelancer will be with the things that are required of you as a corporate entity. Such as, reading up on legislation, accounting rules, dialog with tax office etc.

[ryanlol]

You can do all of those in English without any issues.

[sam_hosseini]

Not everything is in English. Prime example of that is establishing a limited liability online. Nothing impossible to tackle, but just that if things were in English and smooth, maybe I wouldn't have bothered with writing the guide :) It is troubling at times, which is why I wanted to smoothen it out as much as possible.

[mongol]

I seriously doubt it. Now these are not a finnish examples, but Swedish, but I challenge anyone only knowing English:

What is the salary tax breaking point for 2020?

When do you need to have declared and paid VAT during 2020 if you are one a 3 month schedule?

These are basic knowledge questions for a freelancer with a Swedish Aktiebolag, easily googleable in Swedish but challenging if you don't know it.