This is an interesting question, the codepreview integration can operate without a backend, in fact, some existing integrations work this way.
Still, a backend helps to:
1. Distribute the necessary settings/scripts to create a preview, this is now handled by a plain-old (password-protected) file server.
2. Allow users to manage their projects, for example, set variables/secrets, configure a custom domain, etc.
> how is it different from other companies
The main difference is that we did not go to the K8s way, which help us to easily integrate projects without asking our customers to adapt their project to us.
Besides that, there are no bots behind our contact pages, so far, we have a very close relationship with our customers.
> like Retool, Zeet, etc.
I wasn't aware about these tools, still, they seem to be tools for creating applications while codepreview allows generating previews for existing applications.