There are two projects, actually,
One, at https://green.cardsync.xyz/, is a Trello bot that people can just add to their cards and they start syncing. Free accounts get 10 groups of syncing cards, for $19 people can increase that to 50 groups and so on. The other, at https://teams.cardsync.xyz/, is a Trello Power-Up that people can install from their Trello Power-Up menu. It then prompts people to create a bot on their own and register it with the Power-Up, then people can use custom menus that are added to the cards on the boards to which the Power-Up was added to create syncing groups and add cards to these groups. This one uses metered billing.
Besides user management and all that stuff, the actual piece of code that has any value is the code that handles multiple types of webhooks as sent from Trello, gets and puts data into the Neo4j database and sends API calls to Trello in response.
There are two different codebases, the https://teams.cardsync.xyz/ is mostly a copy-paste of the other, but code had to be changed to accomodate the team-focused (instead of user-focused) API and the custom bots (instead of using just a single hardcoded bot for posting the syncs).
