It's popular in German-speaking countries, especially in Berlin, to lure developers to work on startups, offering 0% equity, insane working hours (crushes), barely livable wages, low job protection (small companies can fire more-less at will), all for glory of owners getting pay off at the end if successful (mostly by copying existing US companies and adapting them to local market specifics), being subject to treatment as "idiots" as those owners can't value people that would voluntarily work for them under those circumstances of course.

What type of salary do you mean ? Example is 50K good (normal conditions) ?

Often <45k. You should aim for 70K+ if you want to move to Germany, preferably 85K which would give you middle-class life. 100K+ is fairly rare. Or go to Switzerland and get 250K.