I'm based in Germany and I'm negotiating a job with an American company. Does anyone have experience with the best legal setup for this? Direct employment, setting up my own company and employing myself or freiberufler?

Depends. If it's in Germany, you'll want to consult an employment attorney to figure out the details.

Broad strokes:

If you're working for them directly, they'll handle the details of your employment. If you're remote, they don't need to do anything except pay taxes in Germany, regardless of their incorporation location. If they want you in the states, you'll need a H1-b for long term stays, or for 60 day stints you can use the L-1 visa. Again, it's their job to sort that.

Setting up your own company would likely short change you. Ask an employment attorney about this, again.

If you do it freelance, you'll need to report the earnings and pay your own taxes, benefits, etc on whatever schedule Germany dictates for self-employment.

@SortOfTested I have a feeling freelance is out because if they're your only client, the tax people see that as an attempt to avoid taxes and you should really be treated as an employee.

@DasKoder
You usually don't pay tax on exports. I don't pay vat on anything related to selling goods to the US from the UK for example. They're still using EU rules on those terms.

That's as a company, so check EU/German regs on freelance terms.

@SortOfTested ah, I was asking more about income tax and social contributions for myself. As in, what's the most sensible employment arrangement for everyone...

@DasKoder
For developers freelancing Estonia has a digital citizen framework.
It's said to apply European law and give a value insight to dos and don'ts in the remote work industry.