Full disclosure, I made this. Pick your four cards and the starter, and it shows the total with every fifteen, pair, run, flush and nobs listed, and reads the count out the way you'd say it at the table. There's a tick box for scoring a crib, where only a five-card flush counts.

Calculator: https://cardcouch.com/cribbage/learn/hand-calculator

It runs on the same scoring code as the cribbage game on the same site, free and vs the computer, no account: https://cardcouch.com/cribbage. So if the calculator is wrong, the game is wrong too, and I'd like to know. Hands you think it miscounts, or counting situations it doesn't handle, are exactly what I'm after.

There's also a one-page printable scoring chart if anyone wants one for the table: https://cardcouch.com/cribbage/learn/scoring-chart