I’m looking software solution for a payment gateway with integrated web crypto wallet.
Here are my main use cases:
1. A merchants who want to accept payments integrates his website with my API. When his client wants to top-up a balance merchant will send him to my website so he could buy crypto using credit card and pay merchants invoice. After that I will send the client back to the merchants website.
2. A user registers on my website, passes KYC process, purchases crypto using credit card and gets this crypto to a custody wallet inside my website, then he can send this crypto to an external wallet.
3. A user registers on my website, top-ups his custody wallet inside my website with BTC, purchases ERC20 token from me paying with BTC, and sends this ERC20 token to an external wallet.

Functionality I need:
1. Payment gateway - merchant API, invoicing system;
2. Custody web wallet - support of ETH, ERC20, BTC needed. Something similar to blockchain.com web wallet. Integrated custody solution similar to Bitgo is preferable, but proprietary crypto custody solution with own nodes will also be considered;
3. Buy/sell functionality - so users could buy and sell crypto from me paying with credit card or with another crypto;
4. KYC process - client forms and admin panel, ideally with integrated third party KYC service;
5. Admin panel.

Here are couple of examples:
1. https://www.merkeleon.at/crypto-payment-processing/
2. https://coinspaid.com/processing/