I used Leaderboard-Creator of Danqzq https://danqzq.itch.io/leaderboard-creator (which is free and uses TLS, I checked with Wireshark). At first, I tried LootLocker, but we wanted one leaderboard per level and I was afraid the limit displayed on my LootLocker account (1,000 users) would not be enough. During the tests, the number of users was rising too fast to not be scary.