Hi ,

One of the recruiter asked me to present the system design for the following requirements.

1. we have 10 products and there will be millions of subscriber to this each of the product and a user can subscribe to multiple products and they have common profile across the products, if they change any profile info then it should be validated across multiple products and then once all successful then it should update the profile.

Design the system which will validate the profile change service and update the data.

few things to consider
load on the service will be 5000TPS
there will be new product getting added every month
and response for this service should be in millisecond, for this you can take approach of saving first and done the validation in background asyn and have API to provide the status.