Eleven tabs open, eleven pricing pages, and you still can’t tell which of these tools actually replies to the comment on your post versus which one only messages people who’ve already messaged you. “Facebook auto-reply tool” turns out to cover three genuinely different jobs wearing the same search term, and most listicles compare them on logos and star ratings instead of on what each one does when a comment lands.
A note on honesty: we build Mentbot, and it’s first on this list. Every price below comes from the vendor’s own pricing page, checked on 25 August 2026 and re-checked on 15 September 2026, and we say plainly where a competitor is the better fit — including in Mentbot’s own entry.
Before comparing six of them, it’s worth separating what they do, because the category name hides real differences:
Every tool below fits somewhere in that split. It’s the first thing to check on any tool you’re evaluating, before price.
Price: $9/mo (100 comments/day) to $49/mo (5,000/day), flat, scaled by daily comment volume. Every feature is on every plan, pages are unlimited, and every signup gets a 14-day free trial with full Pro-plan access, no card required.
Mentbot does the paired job above and nothing else: someone comments, they get a public reply and a private Messenger message from the same rule, and the comment can be auto-hidden so a competitor can’t work through your buyer list underneath it. Setup is one rule — all posts, posts carrying a hashtag, or comments matching keywords — that then covers every future post without being rebuilt.
Where it falls short: no visual flow builder, no drip sequences or broadcasts, no AI-drafted replies, and no Instagram or WhatsApp — Facebook pages only. If a flow builder or multi-channel inbox is what you actually need, several tools below do that better.
Choose it if: the job on your page is “reply, DM, maybe hide it,” every day, and you’d rather set that once than maintain a flow.
Price: Free, forever.
Facebook’s own tool sends a private Messenger reply when a comment on your posts contains the words or hashtags you set, using the Comment to message automation in Inbox → Automations on desktop — about ten minutes to set up, no third-party account needed.
Where it falls short: it’s DM-only — Meta’s help centre describes no automation that posts a public reply. It doesn’t say whether you can limit the automation to specific posts, and its pages disagree on whether it matches keywords or only hashtags, so test it on a post of your own first. There’s also no reporting on how many commenters it actually converted. Checked against Meta’s Business Help Center, 15 September 2026.
Choose it if: comment volume is still low enough that you’re not sure paid automation is worth it. Start here — if it’s enough, you’ve saved a subscription. Our Meta Business Suite comparison lists exactly what it automates.
Price (monthly / annual): Free — 25 active contacts. Essential $17 / $14 (250 contacts). Pro $39 / $29 (2,500). Business $99 / $69 (7,500). Advanced $199 / $139 (25,000). Overage runs from $0.10 down to $0.004 per extra contact depending on tier. Verified against manychat.com/pricing, checked 15 September 2026.
ManyChat’s Comments Growth Tool triggers a bot flow when someone comments a keyword on a chosen post — the strongest visual flow builder in the category, with quiz funnels, drip sequences, and reach across Instagram and WhatsApp as well as Facebook.
Where it falls short: you’re building per-post, per-flow, and the bill grows with every unique contact you message in a month — a viral post can push you into overage or a higher tier the same week it made you money.
Choose it if: you’re running multi-step campaigns, not just a reply-and-DM. Our full ManyChat alternatives comparison goes deeper on this specific trade-off.
Price: Business is $69/mo billed monthly, or 10% less billed yearly, with US$20 of AI credits a month. Agency S is $100/mo ($90/mo billed yearly). No free plan is listed; every plan starts with a free trial. Verified against chatfuel.com/pricing, checked 15 September 2026.
Chatfuel covers the same flow-builder ground as ManyChat — Facebook, Instagram, and WhatsApp, an AI sales manager, broadcasts — but doesn’t bill by contact. Plans include unlimited contacts and messages; the fair-use ceiling applies to AI processing instead.
Where it falls short: there’s no free plan — after the trial it’s $69/mo — and you’re learning a flow builder either way, even if all you need is “reply, then DM.”
Choose it if: you want ManyChat’s kind of flow builder without per-contact billing. Our dedicated Chatfuel alternatives comparison covers this specific choice in more depth.
Price: Basic $29/mo (500 AI replies and 2,500 moderations a month). Pro $69/mo (1,500 / 7,500). Enterprise $149/mo (5,000 / 25,000). Ultra $249/mo (10,000 / 50,000). All billed monthly, VAT excluded, with a custom plan through sales above Ultra. Each plan has a 14-day free trial with 500 AI replies plus 500 moderations. Verified against replyzen.ai, checked 15 September 2026.
ReplyZen leans AI-first: it drafts comment replies and private messages using an LLM reading your post and linked product pages, rather than the fixed reply variants most rule-based tools use, and covers Facebook, Instagram, and TikTok comments together.
Where it falls short: the bill follows AI replies, so it climbs with comment volume. If every comment gets a reply, 100 a day is about 3,000 replies a month — the $149 Enterprise plan. Past Ultra’s 10,000 replies, roughly 330 comments a day, the price is custom. You also decide how far to trust the AI: replies can publish automatically, only when it’s confident, or after you approve each one, and review time adds up.
Choose it if: you want each reply written from your post, product pages and knowledge base rather than wording you set once, and you handle Instagram or TikTok comments too. Our ReplyZen comparison prices it at 100, 1,000 and 3,000 comments a day.
Price: Pro $139/mo ($109/mo billed yearly), with 500 monthly active contacts and 10 users. Premium $349/mo ($279/mo billed yearly), with 1,000 contacts. Enterprise is custom. 7-day free trial, no card. Verified against sleekflow.io/pricing, checked 15 September 2026.
SleekFlow is a full omnichannel inbox — WhatsApp, Instagram, Facebook, web chat, and more, with AI agents and multichannel routing across a team. Comment-to-DM is one entry point into an inbox built for a lot more than Facebook comments.
Where it falls short: at $139/mo minimum ($109 billed yearly) for a plan that starts at 500 monthly active contacts, it’s built and priced for a support or sales team, not a solo seller whose whole job is answering Facebook comments.
Choose it if: Facebook comments are one channel among several your team already handles from a shared inbox, and you need the routing and multi-agent tools that come with it. Our SleekFlow comparison works out what 100, 1,000 and 3,000 comments a day cost once flow enrollments are counted.
| Tool | Entry price (monthly) | Billing model | Public reply? | Private DM? | Best for |
|---|---|---|---|---|---|
| Mentbot | $9 | Flat, by daily comments | Yes | Yes | Comments-only sellers |
| Meta Business Suite | Free | — | No | Yes | Low volume, testing the idea |
| ManyChat | $17 ($14 annual) | Per active contact | Configurable | Yes | Multi-step flows, campaigns |
| Chatfuel | $69 (10% off yearly) | Flat; unlimited contacts | Configurable | Yes | Flow builder, no contact metering |
| ReplyZen | $29 | By AI replies a month | Yes | Yes | AI-drafted replies |
| SleekFlow | $139 ($109 annual) | Plan + active contacts | Configurable | Yes | Teams, multi-channel inbox |
All prices verified against vendor pricing pages and help centres on 25 August 2026 and re-checked on 15 September 2026. This category re-prices without warning — check before you buy.
Answer one question: what happens after the comment, today, not in the flow you’d like to build eventually?
Is there a free Facebook auto-reply tool? Meta Business Suite, at zero cost, forever — it sends a private reply from Inbox → Automations. It’s DM-only, fires only on comments containing the words or hashtags you set, and has no reporting, which is the trade for free.
Do these tools all use Facebook’s official API? The ones named here do. That’s the one thing worth checking on any tool you’re considering: anything asking for your Facebook password, or a browser extension clicking buttons for you, risks getting your page restricted.
What’s the cheapest paid option for a solo seller doing comments only? Mentbot at $9/mo, among the tools compared here — the honest caveat being it only handles Facebook comments, so “cheapest” only matters if that’s the whole job.
Can I run two of these tools on the same page at once? Not safely on the same comments. Two tools both trying to send the one private reply Meta allows per comment will race each other; turn one off before turning the other on.
If the job on your page is really just “reply to the comment, DM the price, maybe hide it,” most of what’s on this list is more platform than you need. That’s the gap Mentbot was built into — start a 14-day free trial, no card, and run it against your next product post before deciding. If you’re weighing a specific switch rather than the whole category, our ManyChat alternatives and Chatfuel alternatives comparisons cover those two head-to-head, on the same verified-pricing basis as this one.
