Well, I did tons of research and currently I'm using
bitcoinlib for python to have a wallet which should be able to hold over one million addresses and occassionally broadcast transactions.
It has all the features you'd expect, but I'm concerned about performance when I use more than my current 10 addresses.
The thing is that I'm trying to make an online plattform which relies on the Bitcoin infrastructure and there could be millions of users. Also, I am concerned of how secure
bitcoinlib actually is and I'm missing a neat Graphical User Interface.
Now, there are wallet services like Coinbase which also offer an API but I don't see any explanation on how many addresses they could hold or how many API requests I'm allowed to make. I've found many of those seemingly free services, so Coinbase just serves as an example.
Hence my question, is there any such thing as a free bitcoin wallet service (we're a free platform, so no budget there) which could scan let's say 100'000 addresses and notify our platform of incoming transactions within a few seconds and broadcast about 1000 transactions per minute ?