Yes, but not sure if open source matters with websites. You can't verify if they are running the same code on their servers anyway.

Best you can do is have no-javascript and/or an onion site. They do both.

http://trocadorfyhlu27aefre5u7zri66gudtzdyelymftvr4yjwcxhfaqsid.onion/

You can also use other options on my link that don't require trust (or minimize trust) like Bisq, UnstoppableSwap, BasicSwapDEX. They are all open source software you can run and verify for yourself.