NodeJS API Development for Multi-Tenant Login

I'm seeking a seasoned NodeJS developer to help create an API that manages logins for various software packages. The API should cater to a multi-tenant architecture where each tenant has a dedicated database to ensure data segregation.

Key Features:
- Tenant Identification: The API must require the client to input their tenant name prior to authentication with their user credentials.
- Access Control: The API needs to determine if a tenant has access to the software and if a user can log in on behalf of the tenant.
- Custom Software Packages: The API should support logins for custom Avalonia packages.

The ideal freelancer for this project should have:
- Extensive experience with NodeJS and API development.
- Familiarity with multi-tenant database structures.
- Knowledge of handling access permissions and software compatibility.

Please note that the API does not need to support multi-factor authentication nor does it need to cater to any specific, well-known software packages.