You don't have to run core tho. Any software that follows the consensus rules does fine as well. There's not many that many, popular alternatives tho.
Discussion
Libbitcoin I would consider the only alternative.
Yeap, I saw that, and like you said there's nit much alternatives, and that's a huge risk and point od centralisation IMHO.
..also I read that people running Knot had they node technically attacked somehow.
WE NEED MORE NODES ALTERNATIVES, ALSO WOULD BE NICE ONE WHEN YOU CAN ACTUALLY SEE THE MEMPOOL AND UNDERSTAND SOMETHING ABOUT THE TIMECHAIN, FIRST TIME I DOWNLOADED A NODE I WAS LIKE.. SO NOW, WTF I DO WOTH THIS?