Follow gate
Also called: Follow to unlock, Follower-gated DM, Ask to follow
A follow gate holds back the reward in an automated Instagram DM until the person follows the account, so each comment can become a new follower.
Verified or self-reported
There are two kinds of follow gate. A self-reported gate sends a button such as "I followed" and trusts whoever taps it. A verified gate asks Instagram whether the person really follows the account before it releases the reward.
Verification uses the is_user_follow_business field of Meta's User Profile API. Meta only returns it after the person has messaged the account or tapped a button or icebreaker in the conversation, which is why verified gates check at the moment the person taps the confirm button.
What happens to people who have not followed
A well-built gate does not dead-end them. It explains what is needed, offers the profile, and lets them tap again once they have followed. Some tools stop checking after a few attempts and send the reward anyway, which makes the gate a nudge rather than a requirement.
UnlockDM checks the follow through the API on every tap and only delivers once Instagram confirms it.