The short answer
Klaviyo: a mature platform with a large number of store integrations, used by a very wide range of online brands. Its acceptable use policy restricts products related to pharmaceuticals and medical therapies, and it reviews accounts against that policy.
Amino Engine: an email platform built for peptide brands on purpose. Your mail leaves from your own domain, on servers and IP addresses we run, so no outside email provider sits above your account. Fewer integrations today: WooCommerce now, Shopify next.
If you are not a peptide brand, Klaviyo is a strong choice. If you are, read on.
Who each platform accepts
Klaviyo's acceptable use policy, dated “Updated: April 9, 2026”, says, as of 23 September 2026:
“You may not use the Services to offer products or services related to: ... Prescription medications, pharmaceutical products or services, medical therapies, telehealth, and other related technologies, products, or services.”
The word peptide is not in the policy. Klaviyo decides at review time whether a store falls under that clause. We cover what that means in practice, and what to do after a suspension, in does Klaviyo allow peptide brands.
Amino Engine accepts peptide brands because that is who it was built for. The rule we enforce is the one every inbox enforces: mail people who asked to hear from you. We also expect you to keep claims about human use out of your emails, the same standard the FDA applies to product pages.
Where your mail is sent from
On Klaviyo, your mail goes out through Klaviyo's platform, and your account stays on it for as long as Klaviyo's policy allows. That is true of any hosted email service: the provider above you makes the final call.
On Amino Engine, mail leaves from your own domain, on servers and IP addresses we run. There is no outside email provider above your account. New senders are warmed up over 42 days, so volume climbs gradually and mailbox providers learn to trust your domain. The Pro plan adds your own sending IP.
Store connections
This is where Klaviyo is clearly ahead. Its home page lists “350+ pre-built integrations” (klaviyo.com, as of 23 September 2026), names Shopify among its native ecommerce integrations, and offers a WooCommerce extension.
Amino Engine connects to WooCommerce today through its plugin. Orders, carts, product views and consent flow in on their own. Shopify is next. If your store runs on something else, Klaviyo has the wider reach right now. We cover the WooCommerce side in detail on WooCommerce email marketing for peptide brands.
Flows and campaigns
Both platforms give you a visual flow builder, a drag-and-drop email editor, segments and signup forms. Klaviyo's pricing page describes its free plan as including “drag-and-drop email/SMS editors” and the ability to “build automations, segmentation and reports” ( klaviyo.com/pricing, as of 23 September 2026).
Amino Engine's flow editor is laid out like Klaviyo's on purpose, so nobody on your team has to relearn anything. Ready-made flows cover the ones that earn most for a store, such as abandoned cart, welcome, post-purchase, win-back and back in stock. Forms come as popup, flyout, embedded or a hosted page, with double opt-in built in.
AI agents
Both platforms can be driven by an AI agent. Klaviyo publishes an official MCP server that, in its own words, enables “AI clients to interact with your Klaviyo data”. Amino Engine has an API and an MCP server too.
The difference is in what happens to the agent's work. In Amino Engine, flows and emails an agent builds are saved as drafts. A person reviews them and switches them live. For a category where one careless sentence can matter, we think that is the right default.
Reporting
Amino Engine attributes revenue to the last email click within five days. Opens never count. The number is smaller than an open-based one, and you can trust it.
Klaviyo explains its own model, windows and settings in its help article on message attribution. Read it directly rather than a summary; the settings are configurable per account.
How each one is priced
Amino Engine charges by the emails you send, not by how many contacts you keep. Starter is $79 a month for 25,000 emails, Growth is $599 for 250,000 and Pro is $999 for 500,000 with your own sending IP and a dedicated account manager. For Enterprise, talk to us. If you want us to build your flows and send your campaigns, Done for you is $899 a month on top of a plan. Full details are on the pricing page.
Klaviyo's pricing page describes its plans by active profiles, which it defines as “contacts who may receive marketing emails”, and offers a free plan with limits on profiles and sends. For current paid prices, see Klaviyo's pricing page. We do not quote them here because they change with your list size.
Side by side
Klaviyo facts checked on its public pages on 23 September 2026.
| Amino Engine | Klaviyo | |
|---|---|---|
| Who it accepts | Built for peptide brands on purpose. | Bars products related to “Prescription medications, pharmaceutical products or services, medical therapies” (policy, as of 23 September 2026). |
| Where mail is sent from | Your domain, on servers and IP addresses Amino Engine runs. New senders warmed up over 42 days. | Klaviyo's platform, under Klaviyo's acceptable use policy. |
| Store connections | WooCommerce today. Shopify next. | “350+ pre-built integrations” (klaviyo.com), including WooCommerce and Shopify. |
| Flows, campaigns, forms | Drag-and-drop flows and emails, campaigns, segments, popup, flyout, embedded and hosted forms with double opt-in. | Drag-and-drop editors, automations, segments and forms. |
| AI agents | API and MCP server. Agent work is saved as a draft; a person switches it live. | Official MCP server. |
| Revenue reporting | Last email click within five days. Opens never count. | See Klaviyo's attribution article. |
| How it is priced | By emails sent. From $79 a month for 25,000 emails. See pricing. | By active profiles. See Klaviyo's pricing page. |
| Trial | 7 days free, every feature included, no card to start. | Free plan with limits on profiles and sends. |
| Moving your list | Import contacts, unsubscribes and bounces by CSV from Klaviyo or Brevo. | Documents a CSV export of all profiles, including suppressed ones. |
Moving from Klaviyo
Klaviyo documents how to export all people in your account to a CSV, including suppressed profiles. Import that file into Amino Engine and unsubscribes and bounces arrive as unsubscribes and bounces, so nobody who opted out is mailed again. Flows are rebuilt from our 82 ready-made flows, or our team builds them for you on Done for you. The full walk-through is in how to move from Klaviyo to Amino Engine.
If your Klaviyo account is already disabled, Klaviyo's help article on suspended or disabled accounts explains its account states. Ask support for your data in writing before you do anything else.
When Klaviyo is the better choice
We would rather you pick the right tool than the wrong one from us.
- You do not sell peptides or anything else its policy restricts. Klaviyo is a mature, well supported platform.
- Your store runs on a platform we do not connect to yet, or you depend on one of its many integrations.
- You need Klaviyo products beyond email that we do not offer.
If you sell peptides and run WooCommerce, we built Amino Engine for you. See how it compares with the other options in Klaviyo alternatives for peptide brands, or read the full overview on email marketing for peptide brands.