If you are in a "high scaling" tech company expect the salaries to be higher as Helsinki basically competes with places like Stockholm, Amsterdam, Berlin, etc in salaries for the skilled people to build that stuff. Still no Silicon Valley but really good if you factor in the cost of living/"free" services.
Another thing to add to the salary is that you are truly expected to only work 7.5h per day (8h minus a 30min lunch break). If you work more you will get paid for those hours. So if in SV in reality you end up working 60h work weeks you should be paid roughly 50% more when compared to the 37.5h work week here just from the hours alone. If you work on weekends then even more as those get extra multipliers in Finland.
Also things like being on the 24/7 on call rotation that I see as being advertised as "part of the job" in a lot of job adverts are actually paid time here. So basically you end being paid for the hours outside normal work hours at 50% of your salary converted to hourly salary.
As a beginning developer I made the equivalent of ~3k euro/month in Canada and worked my way up to 5k in 3 years.
With a bit of experience and luck one can then move to the US to make ~15k euro/month and pay 30% lower tax rate, at the expense of basically all functioning public institutions :)
I also know of a few developers making 10k€ / month but I have to say they're very rare to come across in this country.
Now all kind of exceptions will come out the wood works telling me how they are "easily" making 10k/mo by doing something and working for someone who they won't admit. Yes even I know someone who is (or at least was) making 10k/mo, but he was very specialized expert, actual 10x developer. Most people are making far less. 3k/mo seems like the most common salary (again before taxes) for generic tech job.