I ended up using koinly.  It was easy to use and allowed data collection either via API key or upload of transactions.

Thanks for all the suggestions. 

I nosed around on Gemini, but don't see where to find an API key.  I don't have any crypto on there at the moment because I sold everything on there and moved stuff elsewhere.

Last year I couldn't even find a tax preparer who had crypto experience.  Luckily it was a fairly simple return so it didn't matter as much.  And this guy was a CPA. 

This year it is a different matter though.  I did something really stupid and accidentally sold a bunch of crypto.  I realized my error and immediately repurchased the stock, but by that point I had already created a taxable event.  Since purchases had been made over years it is more involved.  Live and learn I guess.  Sigh.....

Is there a recommended crypto transaction aggregator?  This year I need one for income tax purposes.  How do they work?  Do you have to go into each exchange and download transaction history, or can an aggregator access various exchanges (given user id info, etc.):