There's ShapeShift, Changelly, Komodo and Rubix. Some wallets are non-custodial, meaning you control the keys and they can't steal your money. I recommend going with those. I'm not sure what it means if a wallet is both non-custodial and closed-source though. More on this topic here: https://www.forbes.com/sites/lukefitzpatrick/2019/09/02/a-complete-beginners-guide-to-atomic-swaps/#4c12b2c46178