Comment-to-DM automation
Also called: Comment to DM, Auto DM on comment, Keyword auto-reply
Comment-to-DM automation sends an automatic Instagram direct message to anyone who comments a chosen keyword on a post or Reel.
How it works
A creator posts a Reel that says "comment GUIDE and I will send it to you". Instagram notifies the automation tool of each new comment through a webhook. The tool checks the comment for the keyword and, on a match, sends the commenter a private reply: a DM that carries the link, file or code that was promised.
The DM is sent through Meta's official Instagram Messaging API, which only works for Professional (Business or Creator) accounts. Tools that log in with your password or drive a browser are not using this API.
The rules Meta sets
Each comment buys exactly one private reply, and it must be sent within 7 days of the comment. A second message is only allowed if the person replies, and then within 24 hours of their reply.
Meta also caps how fast private replies can go out. Its Graph API rate-limit documentation puts the ceiling for replies to post and Reel comments at 750 calls per hour, so a Reel that pulls thousands of comments in its first hour is delivered over several hours, not instantly.
Why creators use it
Commenting is one tap, while "link in bio" asks people to leave the Reel, open a profile and find the right link. Every comment is also engagement on the post itself. Optional steps such as a follow gate or a referral link turn the same comment into a new follower or a new participant.