@NotATether you are suggesting to generate a private key for every user, that something I can do. I found library to do that, I am able to generate private key of each user and get associated btc address without having bitcoin core. So I have to find the solution to create and sign a transaction from a private key.
1. How popular is the library?
2. Does the library have option to backup/restore private keys?
3. Have you checked whether it can handle thousand address?
The problem is that you still need a source to get the transactions, as well as the data for your transactions. You cannot do this without running an instance of Bitcoin Core or another full node/client.
You could use 3rd party API, but it's definitely not ideal option when you handle money.
1. The library is popular 200 stars on github
2. I can generate a private key and use it to made operations with the library. That's using
https://libbitcoin.info/3. As I understand, that is only cryptography operations, so that can handle thousand address.
But yes I will have to maintain a bitcoin core even if I use this option, so why not using directly my bitcoin core RPC API with one wallet and multiple address ?
Someone told me that I can use this service from blockchain.com :
https://github.com/blockchain/service-my-wallet-v3 I have to install a service on my server and I will be able to use an API.
Do you know more about that ?
Of course 3rd party API is the best way but the cost is incredible few thousands $ by month... (Bitgo for example)
