Most password managers solve the “too many passwords” problem by storing them somewhere, either locally or in a cloud vault. HIPPO takes a different approach: it never stores anything at all.
HIPPO (Hidden-Password Online Password) is a browser extension that derives a unique, high-entropy password for each site on the fly, using your master passphrase and the site’s domain as inputs. The core mechanism is an Oblivious Pseudorandom Function (OPRF) protocol, which works roughly like this: the extension hashes and blinds your master passphrase, sends that blinded value to a central server, and the server processes it with its own secret key. Neither side ever sees the other’s raw secret. The result is a deterministic, site-specific password that gets auto-filled by the extension.
Because nothing is stored, there’s no vault to breach. The derived passwords are consistent, so you’ll get the same password for a given site every time, as long as you use the same master passphrase.
A small user study with 25 participants compared HIPPO against traditional manual password entry. HIPPO scored higher on perceived security (4.04 vs 3.09 out of 5) and trust (4.00 vs 3.30), and was also rated easier to use despite requiring an extra activation step to trigger the extension.
There are real tradeoffs worth noting. The HIPPO server is a single point of failure: if it goes down, you can’t derive passwords. The system also doesn’t yet handle two-factor authentication. And the researchers haven’t fully addressed what happens when you need to change your master password, or what to do if an account gets locked out after a derived password is rejected.
HIPPO is still a research concept, not a live service. The team plans follow-up studies on longer-term usage, master password change scenarios, and account lockout risks.

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HIPPO is a research-stage browser extension that eliminates password storage entirely by deriving site-specific passwords on the fly. It uses an Oblivious Pseudorandom Function (OPRF) protocol: the extension blinds your master passphrase and sends it to a server, which processes it with its own secret key — neither side sees the other's raw secret. The result is a deterministic, high-entropy password per site that gets auto-filled. A 25-person user study found HIPPO scored higher on perceived security and trust compared to manual password entry. Key tradeoffs include server dependency as a single point of failure, no 2FA support, and unresolved master password change and account lockout scenarios. HIPPO remains a research concept with no live deployment yet.

HIPPO is a storeless password manager that derives site passwords on the fly using cryptography

The problem is: “perceived security” and “trust” aren’t very regarded metrices in cryptography.

would be nice if the server could run on your own phone, and sync devices, sor of what Authenticator app does