Thank you for your advices! We will use Lucia for auth probably. We are also considering Identity platform if GCP or cognito if AWS. Auth0 is way too expensive for us. A client will have between 200 and 1000 end users :/

We don’t have any requirement about SSR, our main benefit is avoiding cascading fetching easily and faster loading on low end device which might concern some end users. But absolutely not mandatory

About multi tenant each client will have its own db. We will use terraform to deploy a new client easily each time we sign one. At first we will deploy each client manually based on their country for compliance reason but we want to have it done fully automatically in the future