I've been liberally trading cryptocurrencies for the past several years and ended up with a bit of tax nightmare, with thousands of trades across many exchanges. I found my self with little choice but to write my own capital gains calculator. At the time I needed it, I couldn't find a suitable open source solution, and I have privacy concerns about paid services. It's no longer just for "personal use", as I've recently published it on GH https://github.com/dleber/capitalg