How to check the balance of the list of 1 million Bitcoin Addresses? Is there such a program?
Insight Block Explorer is the program. It has an API you can query.
You'll need to install the block explorer. It runs in a nodejs environment.
You need to install a bitcoin full node, then create a program to scan from latest block to first block all the unspent outputs and keep in memory, maybe in something like Redis, the status of the balances of the addresses until you reach the 1 million you are looking for