For the first part they have https://openrouter.ai/docs/guides/overview/auth/oauth (which I haven't used). That gives you an openrouter key for that user (openrouter bills the user).
What value are you providing that you'd take some further cut? You could take the money from the user via stripe and then pay your own openrouter bill instead.
This simplify integrations. Right now you have to maintain your own billing credits for user and even maintain user database, abuse detection, planning when you have to top up your openrouter accounts etc. Lots of hassle and this is a reason why many developers charge e.g. more in subscriptions the end user.
It's more user and developer friendly when you tell your user:
- you don't have to create new account just log in to your openrouter account
- bring your own key
- you don't have to pay any subscription. we charge small markup fee (e.g. 5-10%) over your usage inside our app.
I am using oauth already. Thanks. I really need the second part.