OpenRouter’s “moat” is currently “why would I use anything else?”.
Stripe has presumably only purchased them because they think there’s consumer-surplus to monetize here, which presumably will soon be giving me lots of reasons to use something else.
It isn't clear to me what advantages OpenRouter has over running a similar router-aggregator locally for ~free. I guess they have stronger bargaining power than a solo engineer or small startup, and can therefore negotiate volume discounts with model providers. The question is if those discounts let them offer cheaper rates than a local router-aggregator even after the markup. And if they can do that, then OpenRouter is undercutting the providers themselves on price, which I would imagine the providers would not want to see.
Stripe has presumably only purchased them because they think there’s consumer-surplus to monetize here, which presumably will soon be giving me lots of reasons to use something else.