How many CAPI gateways needed?

If my agency manages multiple clients, and all of the pixels are available under my account via Business Manager, do I still need one server per client? It seems like I would, so that the server events can fire from the respective client domains. (capi.client1.com, capi.client2.com, etc.).

So I think this means it’s $100/mo per client, regardless of how large or small the client is?

BUT I saw someone mention something about multiple DNS records. If I set up multiple DNS records to point to the same CAPI-G gateway, will the server know which domain to fire the conversions from?

You can use one FB CAPIG instance for several domains and pixels (all must be under the same FB Business Manager). CAPIG instance will run on one custom domain from your BM. All other domains and pixels will use the same custom domain (CAPIG instance) —no need to create a separate domain for all sites.
Check FB documentation.

@Ira thank you. I had tried that, and I was getting conversion events from one domain showing up on another company’s pixel. When I looked at which URLs were sending data to Client A, Client B’s URLs were showing up, which was concerning. (Full disclosure: this was using my own Amazon CAPI-G, not Stape’s.)

Most likely, you have these errors because of the wrong configuration. We do not have such issues. I suggest checking how you connected new domains and pixels.

With Stape’s CAPI-G, is the fee a flat $100 regardless of how many websites are connected?

Yes, That’s correct.