I have received 3 invites from Chris (I might have screwed up the PGP email, but thanks anyway), added to my account https://keybase.io/josipfranjkovic. Using race conditions, I was able to send out a total of 7 invites to my throwaway emails, obviously bypassing the 3 invitations limit.
Here are the steps to reproduce:
1. Login to your Keybase account, which has >0 invitations left.
2. Go to https://keybase.io/account/invitations
3. Enter an email, and click the invitation button
4. A POST request will be sent to
/_/api/1.0/send_invitation.json. Repeat this POST request multiple times in short time frame, and change the
(I have reclaimed the invitations for further testing)