(Replay engineer) Google is currently the only way unfortunately. We wanted to support secure logins at launch, with SSO and Multi-factor Authentication, and focus most of our efforts on the core product. As a result we just went with Google for launch.
We don't currently have any plans to add additional authentication mechanisms but we've heard this feedback from a couple folks and we'll sit down to prioritize it after the excitement of launch has died down. Sorry about that!
Even for Google logins, would you consider using a token-based authentication system (like Spotify, Postman, etc. do)... i.e., your default browser opens, Google logs you in there (or you already are), and that sends a backend auth token to your service to connect your Google and Replay accounts.
I would like to try your product, but am wary of typing in my Google credentials into an unknown, black-box browser. It's too easy to MITM, especially if someone redistributes a copy with a keylogger shimmed in.
The token-based auth means you can still log in with Google but never have to share your Google password with the proprietary Replay browser. Probably many of the multi-login vendors support something similar already if you don't want to deal with it yourself.
Thanks for the update. I had a feeling that this might have been the case due to the launch crunch and it's perfectly understandable. Really excited for the future of this project!
We don't currently have any plans to add additional authentication mechanisms but we've heard this feedback from a couple folks and we'll sit down to prioritize it after the excitement of launch has died down. Sorry about that!