In Sweden it's pretty easy as an developer:

1. Start a business

2. Start contracting anything north of 80$ will give you a really solid income

3. Through your business give yourself a ~45k SEK a month salary

4. Pay yourself dividends from the business profit. You pay very low taxes on dividends

This is a model many many SW engineers in Sweden follow, also running your own business it super simple and for finding clients you can use bigger contracting firms(AFRY) which will take a % of your hourly salary.