They are the injured party. It isn't clear to me why they filed in federal court though. This looks like a simple contract dispute and federal courts do not have general jurisdiction over torts or contracts. Are Parlor and Amazon located in different states? Is there some federal law in question?
I imagine that they are alleging some antitrust-based cause(s) of action. I can’t remember if that is solely federal jurisdiction or not. That’s been a minute (or a few decades) since I studied the subject. I look forward to reading their complaint later on.
I am not sure why but one thing I do know is that it takes years to get a court date with the federal system.
“It isn’t clear to me why they filed in federal court though. This looks like a simple contract dispute and federal courts do not have general jurisdiction over torts or contracts. Are Parlor and Amazon located in different states? Is there some federal law in question?”
Parler is headquartered in Nevada, Amazon in Washington. As long as the dispute is over $75,000 (clearly is), there is federal diversity jurisdiction. That is even assuming there is no anti-trust claim, which there may well be.
Interstate commerce.