Tenant

Any customer that you sign up to use your SaaS environment is one of the tenants of your system.
The sum total of all the customers using your SaaS environment are the tenants.
Each tenant pays for access to the SaaS application by paying a subscription fee.
Tenants are distinct from users.
Multiple users from a single organization, company, or group form a single tenant.
ref: https://learn.microsoft.com/en-us/azure/architecture/guide/multitenant/overview

Considerations

What exactly is tenant for you? A customer, user or a group of user (like team)
- For example, a music streaming service might support both individual users and families.
What commercial pricing models will your solution offer, and how will your pricing models affect your multitenancy requirements?
Do any of your tenants have unusual or special requirements?
- For example, biggest customer need higher performance/stronger guarantees than others

Have an identity service which then can be used in requests to identify you
For each customer, we can have:
- separate services or single service?
- separate databases or single database with tenantId as filter?
Implications:
- Security: Be careful not to access data from one tenant when you return response to another
- Cost: Shared is more cost effective
- Performance: Shared is less performant
- Reliability: Shared can cause single point of failure for all tenants

tenancy-models