Most notably the French. The French crown poured tons of money into supporting the Revolution, as a way of getting back to the English for defeating them in previous wars. French officers were also present at the surrender of British forces in America.

This was also partly a reason that the French Revolution happened, but that is a different question.

It's difficult to estimate figures, because it was clandestine, but some Americans did (shhhh!) continue to trade with the British Empire during the Revolution through the magic of smuggling. Trade barriers weren't impenetrable, people found ways to get around them and often economic incentives beat patriotic ones, especially in areas which had closer connections to Canada or the Caribbean than they had to Washington.