Search around for multitenant architecture or just multitenancy. Domain-wise, there are multiple ways to do it. AWS has an SDK where you can dynamically add new DNS records to Route 53. Or you can create a wildcard DNS record so a web server can answer to <anything>.mydomain.com -- any subdomain works without having to create a new DNS record.
For data security, you have to associate a tenant ID to each user account anyway, to make sure they can only access their own data. The subdomain things is really for display/customized-link purposes when using multi-tenancy.
You can also deploy multiple copies of your app instead of using multi-tenant-aware system, but that can become difficult to manage as you add more customers.
I’ll definitely do some research. My intention at first was to assign a copy to each user.
Now I have more options. I shall see.
We're a place where coders share, stay up-to-date and grow their careers.
We strive for transparency and don't collect excess data.