[WALLET] How do I know which transaction is from whom?

Hey guys, how should I confirm when someone claimed sent me some grins?

You can view your sent and received transactions using the grin wallet txs command. Note that this historic information is lost when you delete your wallet, it can not be reconstructed from the seed.

Are there any more specific information I can use to identify the sender if there are few transaction arrive at the same time?

Have the same question, like If I want to sell something on a webpage, how do I check who has paid and who still needs to pay?
Is there somekind of data that the sender can attach, and that I can see?

Well, grin will be adopting the idea proposed in the BIP 33, which states the introduction of hierarchical deterministic wallets. If you are not familiarized with HD wallets, I recommend you to watch this video: https://www.youtube.com/watch?v=2HrMlVr1QX8/.

From a business perspective, the logical process of identifying a grin transaction could work as it works today with every BIP33 coin in centralized exchanges.

I know HD Wallets, but than I only will have a lot of wallets.
So do I need a wallet listener per wallet? that doesn’t make any sense.

I am missing something like a payment Id or anything that I can attach to a tx so that the receiver knows that I was sending it.

What is possible that the user sends me his first tx data and than I spin up a wallet only for that user to build the receivers part of the tx and give it back to the user.
I than watch that wallet for incoming funds.

That sound like a pain, It would be much easier to have one wallet listener, that can identify and credit incoming tx to different users.