Hello,

Correct, it is 20 for the pro plan.

May I ask what your use case is?

I have a LMS like website which customers (coaches) may want to have their domain for it. I have a similar setup for a LMS I am using. My custom domain for them is hmba.zelner.com. And when they got me to add academy CNAME as a DNS record on my own website (harishmarnad.com), I was able to direct academy.harishmarnad.com to their subdomain.

Similarly, I let coaches create subdomains on my plaform (hmba.dev.supercoachai.app) but when I tried to add a cname (devgo) in my personal website (harishmarnad.com) to point to this subdomain, railway is saying academy.harishmarnad.com should point to it directly and not via cname like I have in zenler LMS.

Given this, either I need to make it work like zenler with your help or I may need to be able to add custom domains to railway as and when I get a request from a coaching customer. Hence wanted to know the limit and how far I can take it and the process for it.

Please let me know the best way to proceed and the process for it.

If I understand the flow correctly:

1. On your service, clients can generate a subdomain

2. You want those clients to be able to bind a custom domain to that subdomain (via CNAME)

Do you think a reverse proxy might work for your use-case? It could work in two ways:

Manually

You can manually create reverse proxy services for clients and provide them the CNAME of the reverse proxy, where the reverse proxy would proxy their custom domain to your domain

Automatically

You can build a reverse proxy that communicates with your service to find custom domains; if a request comes in, it checks with the registered custom domains and proxies it appropriately.

When a client registers a custom domain:

1. automatically find a free reverse proxy service (<20 domains registered) via the Railway API (projects query -> domains query)

2. then register the custom domain there (customDomainCreate mutation)

3. and then present its CNAME record to the client to register in their DNS ( customDomainCreate mutation -> status.dnsRecords)

If no reverse proxy service has free spots available then:

1. create one (with the Railway API via serviceCreate mutation)

2. and provide that service's CNAME record to the client instead ( customDomainCreate mutation -> status.dnsRecords)

Side Note: Remember to manage CORS in this process too