I don't think there is a site that will show you this information, but it is fairly trivial to find out.
Here's an old Bitcointalk thread that discusses this: https://bitcointalk.org/index.php?topic=29675.0
Here's a python script that will calculate it for you. You will need a bitcoind for it to connect to:
from bitcoinrpc.authproxy import AuthServiceProxy, JSONRPCException
import binascii
import struct
def uint256_to_str(u):
rs = b""
for i in range(8):
rs += struct.pack("<I", u & 0xFFFFFFFF)
u >>= 32
return binascii.hexlify(rs)
def uint256_from_str(s):
s = binascii.unhexlify(s)
r = 0
t = struct.unpack("<IIIIIIII", s[:32])
for i in range(8):
r += t[i] << (i * 32)
return r
def byteswap(a):
return "".join(reversed([a[i:i+2] for i in range(0, len(a), 2)]))
# rpc_user and rpc_password are set in the bitcoin.conf file
rpc_user = "user"
rpc_password = "password"
rpc_connection = AuthServiceProxy("http://%s:%s@127.0.0.1:8332"%(rpc_user, rpc_password))
best_hash = uint256_from_str("ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff")
best_height = 0
counter = 0
while True:
try:
commands = [ [ "getblockhash", height] for height in range(counter, counter + 10000) ]
block_hashes = rpc_connection.batch_(commands)
for block_hash in block_hashes:
block_uint256 = uint256_from_str(byteswap(block_hash))
if block_uint256 < best_hash:
best_hash = block_uint256
best_height = counter
counter += 1
print("Processed " + str(counter) + " blocks")
except Exception as e:
print(e)
break;
print("Lowest Block Hash: " + byteswap(uint256_to_str(best_hash).decode()) + " at block height " + str(best_height))
This script gave me the following output:
Lowest Block Hash: 00000000000000000000011246f099d94f91628d71c9d75ad2f9a06e2beb7e92 at block height 458091