In the early days of crypto, Airbitz was a Bitcoin-only wallet that featured a directory of brick and mortar businesses which accepted Bitcoin. It was one of the only mobile wallets which allowed the user to own their private keys without having to see them.
While it was very popular as Bitcoin wallets go, the era of Ethereum and beyond made it necessary to adapt to people who expect to be able to use more than one cryptocurrency. Today, its descendant is called Edge, a modern multi-asset wallet, modular in design, which is focused on user-friendliness.
Puey says that the Airbitz codebase was so ingrained in the Bitcoin architecture that they had no choice but to rebuild much of it from scratch, keeping intact the core security model: Edge servers never see your private key, you own your coin and can take your private key with you between devices and even wallets.