Do you have a fully synced full node?
If you have, you can get the info yourself using the console/rpc through: getbestblockhash, then getblockheader "block_hash" commands.

You can also use https://chainquery.com/bitcoin-cli/getbestblockhash and https://chainquery.com/bitcoin-cli/getblockheader to do the same.

Why SlushPool in particular?