Adding this here, just for visibility:
$ curl 'http://localhost:3000/invites.json' -X 'POST' \
-H "Api-Key: d5fc02c5f4efaafacc82e4ff3410ae283d1c5da68ac43430d5133aaf4785593f" \
-H "Api-Username: dan" \
-H "Content-Type: application/json" \
-d "{\"max_redemptions_allowed\":5}"
{"id":18,"link":"http://localhost:3000/invites/6f524dba4ced35ecae709a8614db3b05","redemption_count":0,"max_redemptions_allowed":5,"custom_message":null,"updated_at":"2021-03-10T15:44:44.259Z","expires_at":"2021-04-09T15:44:44.258Z","expired":false,"topics":[],"groups":[]}%
I will be updating our API documentation. Thank you for bringing that to my attention and sorry for the inconvenience.