"Auto comment" means two different products, and one of them will get your account restricted. Before anything else, be sure which one you are looking for.
The first kind posts comments outward — your account drops "Great post! 🔥" on strangers' photos to farm attention. Instagram treats that as spam, correctly, and tools that offer it work by holding your password and puppeting your account. Skip the whole category, free or not.
The second kind answers comments on your own posts: someone comments "price?", your account replies with the price, or replies publicly and sends the details in a DM. That is what Meta's official API exists for, it is allowed, and it is the thing you can genuinely run for free. This post is about that kind.
What free gets you
A workable free setup needs four pieces, and all four exist without a card:
A trigger. A keyword in a comment — "price", "link", "want" — scoped to one post or to all of them. One-word triggers work best when the post itself asks for the word ("comment WANT and I'll DM you the guide"), because then the comment is unambiguous.
A reply in your own words. Not "Thanks for reaching out! 💕" — the sentence you would actually type. Write four or five variants, because the same string posted forty times under one reel is visible to everyone reading the comments, and it is what makes automation obvious.
A public reply plus a private one. The pattern that converts is a short public acknowledgement ("sent you a DM!") with the real content in the DM. The public half tells everyone else the comment section is alive; the private half does the selling.
A refusal. The piece almost nobody ships free: something that holds the reply when the comment is angry, off-topic, or a question your setup cannot actually answer. An automation that answers everything is worse than none, because the wrong reply is public.
The free tier you want is not the one with the most replies. It is the one that refuses to send the reply that would embarrass you.
Where free ends
Templates are free because they should be — you wrote them. What costs money anywhere honest is generation: a model reading the comment and writing a fresh reply in your voice. On our free plan you get 100 AI replies a month with templates and triggers uncapped, and that split is the industry's fairest shape: the marginal cost of a template is zero and the marginal cost of a generated reply is not.
If a tool advertises unlimited free AI replies, the model is cheap enough that you are the product, or the "AI" is a template with your first name substituted in. Read what free automation costs you anyway before you spend the afternoon on setup — the honest costs are time, not money.
Setting it up in one afternoon
- Pick one post where comments already ask the same question repeatedly. Do not start with "all posts".
- Write the trigger list from the comments that actually exist — open the post and copy the words people used, including the misspellings.
- Write your reply variants by reading your own past replies. Steal from yourself, not from a template gallery.
- Add the negative cases: if "price" should not fire on "no price", say so.
- Test on yourself before going live, and read the result on a phone — that is where your audience reads it.
Run one post for a week, read every reply it sent, then widen. The creators who get burned are the ones who go from zero to everything in one evening.
What never to automate
Complaints, refund requests, and anything where the person is upset. A template cannot de-escalate, and a generated reply de-escalates in a voice that is not quite yours, which is worse. Every serious tool holds these for you to answer yourself; if the one you are trying does not, that is the tell it was built to send, not to represent you.
Related: the complete comment automation guide goes deeper on trigger design, and comment-to-DM funnels covers the conversion math.