Salaries for IT/software engineering in Germany work kind of the opposite of the US: generally speaking, you’ll make better money in mid-size cities at one of the big old industrials (e.g.: Siemens, Bosch) than in startup-hot Berlin. IG Metall Tariff is what you’re looking for.
I’ve snickered at a couple recruiting mails trying to get me to leave my “boring” giant family company’s IT department for a ~30% paycut and “usually under 45 hours” workweek (mine’s currently 35).
I am “in Tariff” - my base salary is determined by the main IG Metall contract for Bavaria. My employer can pay me up to 28% over that base amount based on my annual performance evaluation. If they want to reward me more, they can choose to bump me up a step. If they wish to pay me even more than that, I am then “außer Tariff,” which means they can pay me as much as they like over that higher minimum, and I’m no longer “limited” to a 35/40 hour workweek. Managers in my department are usually AT, but I also have several IC colleagues with 15+ years of SWE experience who are.
TL;DR - Germany values boring; go boring, get paid.