Starting salary is actually pretty much exactly 3k in Helsinki. In most companies as a pure software engineer you can expect the salary to top out somewhere between 5 to 6k. If you are willing to take on management roles you can go higher easily (especially in older/more traditional companies that don't believe in paying engineers that much).
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.
