API size limits

Are there any size limits on API calls? I’m looking to add 70’000 members into a group using the add group members API call which I guess is roughly 2 megabytes of payload data in the call.

No, but there probably should be. I’d be surprised if that worked because there is a limit depending on how long the request takes. It could time out on you. Probably best to break it up into many api calls and space it out. There is a rate limit on invites if you are passing in notify_users: true as that sends out emails.