Monet is a credential broker for AI. End users connect their existing ChatGPT Plus or Claude Pro account, or paste their own provider API key, and third-party apps route inference through their credential instead of paying for it themselves. The app never sees the credential. The user can revoke it anytime. I have been building it solo since June, it is live and free through the beta, and there is a demo app running the entire flow at demo.monet.gg.
This post is the architecture, plus the reasoning behind the three or four decisions that actually mattered.
The problem with "paste your key here"
BYOK (bring your own key) is usually implemented as a password input and a database column. That design has four separate problems:
Trust. The user hands a live billing credential to an app they just met, with no visibility into how it is stored.
