Design a Merchant Payout System

Ebay interview for MTS 2 - design ebay merchant payout system

Design a payout system for an e-commerce platform that transfers payments to sellers for the orders they have successfully fulfilled. The platform does not handle payments directly — instead, it makes payout requests to an external payment processor, which debits the e-commerce platform’s account and credits the seller’s account. The payment processor charges a commission per payout request. To minimize commission costs, the system should reduce the number of payout requests by aggregating multiple eligible orders for the same seller into a single payout, wherever possible. At the same time, the system must guarantee strong financial correctness: No fulfilled order should be missed in payouts No order should be paid more than once Payout state should remain consistent even in the presence of failures, retries, or concurrency Design the system to support scalability, reliability, and auditability while meeting the above constraints.

Design a payment system to periodically pay out merchants after ensuring you accept 10k TPS of incoming payments.