I have created a web app in python and when a user completes sign up on that application I would like to send them an invite to the slack workspace automatically. I have just started to look at slack API but I can't seem to find it. Is it not possible?
There is an undocumented method in the Slack API that does it.
https://github.com/ErikKalkoken/slackApiDoc Specfically for invite https://github.com/ErikKalkoken/slackApiDoc/blob/master/users.admin.invite.md
Check that out for undocumented slackApi calls.