I want to build a marketplace, so there is a buyer and a seller. So when a buyer buys something from the seller I take the fee. Thus part of buyer's money goes to my account like (10%) and the rest to the seller.
This is possible using 2of3 multisig in which 1 key with buyer, 1 with seller and 1 key with you
Consider an example for a marketplace in which people are selling computers. Every time an order is executed to buy/sell, it would create a multisig address, buyer sends bitcoin to this address in funding transaction, seller would ship computer to the physical address, buyer would confirm the delivery and a release transaction would spend multisig UTXO with 2 outputs (1 for payment to seller and other for fee sent to your address)
Is there any payment provider in the crypto world that allows that, either through a payment provider or to code it by myself? Or if there isn't, what's possible solution for my problem?
You can use Bitcoin Core or Knots JSON-RPC or one of the Bitcoin libraries to achieve this.