Hail is a multicoin cryptocurrency wallet, designed to be able to support many different cryptocurrencies and currently supporting bitcoin and ethereum.
Hail is named after the While at bitpay, I became very interesting in the bitpay wallet client and spent a lot of time trying to understand how it worked. At the time, the bitpay wallet client ( and it's open source variant, copay ) relied on a custom backend called BWS or bitpay wallet services ( CWS was the open source variant ). While poking around the code and trying to understand how wallet software worked, I realized that some private/public keypairs were stored server side to make it easier to detect which addresses belonged to which user, and had this confirmed by a senior dev.
The senior dev told me it was impossible/infeasible to do this any other way, however I didn't agree. Having spent some time looking into how noncustidal wallets worked, and after some conversations on #bitcoin-dev I felt confident enough to try to prove that senior dev wrong.