Customer.io vs Brevo

What each bill counts and how a growing list behaves

Customer.io's billing documentation says people and objects both have profiles and both count toward the plan. The count is a high watermark: if a profile exists at any point in the billing period it counts for that month, even if you delete it. The same page gives the arithmetic for a month that starts with 3,000 profiles, adds 250 and deletes 50. You hold 3,200 at the end and are billed for 3,250. Profiles in test or sandbox workspaces count too, because the account page adds up all workspaces.

Brevo's plans article sets out a different mechanism. When you choose a paid plan you choose a monthly email volume. That volume decides the tier and the number of contacts you can store: 5,000 emails stores up to 500 contacts, 10,000 stores 1,500, 15,000 stores 2,500, and volumes from 20,000 store up to 500,000 on Starter and Standard. If you pass the contact limit on one of the first three tiers Brevo moves you up a tier automatically, and the subscription cost rises with it.

The consequence is that a growing list costs Customer.io money continuously, in steps of $45 to $90 per extra 5,000 to 10,000 profiles on the selector, while on Brevo it costs nothing until your sending plan changes. A team that mails its base four times a month and doubles the list barely changes its Brevo bill. A team that adds a lifecycle program with twelve emails per person changes it a lot.

Cost over a year at five list and volume combinations

I priced Brevo on Standard, because automation for an unlimited number of contacts is a Standard feature and Starter stops at 2,000 contacts entering automations. Figures are the monthly-billing readouts on 2026-10-07. Brevo's yearly toggle subtracts 10%: Standard's smallest tier reads $16.17 instead of $18.

5,000 contacts receiving 4 emails each is 20,000 emails. Customer.io Essentials is $100 a month, 12 x $100 = $1,200. Brevo Standard at 20,000 emails is $69, 12 x $69 = $828. Brevo is $372 a year cheaper.

10,000 contacts receiving 5 emails each is 50,000 emails. Customer.io is $145 a month, $1,740 a year. Brevo Standard at 50,000 emails is $97, $1,164 a year. Brevo is $576 cheaper.

20,000 contacts receiving 5 emails each is 100,000 emails. Customer.io is $235 a month, $2,820 a year. Brevo Standard at 100,000 emails is $139, $1,668 a year. Brevo is $1,152 cheaper.

50,000 contacts receiving 3 emails each is 150,000 emails. Customer.io's selector shows $505+ a month, so at least $6,060 a year. Brevo Standard at 150,000 emails is $179, $2,148 a year. Brevo is at least $3,912 cheaper.

Now the case that reverses the order. 5,000 contacts receiving 30 emails each (event-driven alerts, digests, onboarding nudges) is 150,000 emails. Customer.io stays at $100 a month because Essentials includes 1 million emails, so the year is $1,200. Brevo Standard at 150,000 emails is $179, so $2,148, which is $948 more. At 10,000 contacts the same effect appears between 100,000 emails (Brevo $139 against Customer.io $145) and 150,000 emails ($179). Above 150,000 emails the Standard slider reading I captured ends, and Brevo's Professional plan, which covers 150,000 to 10 million monthly sends, starts at $499, or $449.08 on the yearly toggle.

• Prices come from the Customer.io pricing page and the Brevo pricing page, read on 2026-10-07.
• Customer.io overage if you pass a plan: $0.009 per extra profile and $0.12 per extra 1,000 emails on Essentials.
• Premium on Customer.io starts at $1,000 a month billed yearly, and Brevo Enterprise reads from $2,499 a month with a talk-to-sales button.

Sending product events and starting automations

Customer.io's events guide treats an event as a name plus data of any shape, with nested fields available to segments and templates. You can send events from the JavaScript source, the Pipelines API, the mobile SDKs, a CSV or from inside another automation, and you can fire a test event from the interface to watch a workflow start. Anonymous events are attached to a person once they are identified.

Brevo's Events API logs interactions with contacts and is used to build history, segment contacts and trigger workflows. Its tracker comes in two forms. The JavaScript tracker records page views by itself, while the REST implementation needs an email in every call and cannot track who clicked your emails. Brevo's rate-limit page lists 10 requests a second (36,000 an hour) for POST /v3/events on the general tier and 20 requests a second on the advanced tier, without mapping those tiers to plans in the text I read.

The rate matters for a backfill. Replaying 100,000 historical events at 10 requests per second takes 100,000 / 10 = 10,000 seconds, about 2 hours 47 minutes, assuming one event per call. Customer.io's Pipelines API accepts 1 MB per batch, so the same history goes in as a handful of batches.

On the trigger side, Brevo's trigger article counts over 20 triggers, lets you combine several so a contact enters when any one matches, and refines them with event filters (on event properties) and contact filters (on attributes, email activity and subscription status). Its troubleshooting article adds two warnings: the tracker can only identify someone who logs in or arrived from a Brevo email, and a large import will not push contacts into an automation that starts when a contact is added to a list.

Company data, deals and the CRM question

A B2B SaaS usually needs to message a user based on facts about the company: plan, seat count, renewal date, account owner. Customer.io models that with objects. Essentials includes two object types, such as Companies and Workspaces, each linked to people through relationships, and its object triggers can start an automation when an object or a relationship changes. The documentation states that objects cannot be related to other objects.

Brevo has a lighter CRM built in and a thinner object model. Its plans article says every plan includes free sales tools: 50 open deals and one sales pipeline. Sales Essentials adds unlimited deals and pipelines, multi-user access and sales automation for $31 a month, and Sales Advanced is $64 a month on Professional and Enterprise. Custom objects are a Professional feature at one object and an Enterprise feature beyond that, with a management API that caps a record at 500 attributes. On Standard, company facts go into contact attributes.

Customer.io does not ship a CRM. It reads one: its Salesforce integration syncs contacts, leads, accounts and account-contact relationships, and its HubSpot integration syncs contacts and companies. If you already run Salesforce or HubSpot, that is the cleaner path. If you run neither and have two reps, Brevo's included pipeline is a real convenience.

Channels beyond email

Customer.io lists push, in-app and webhook messages as unlimited on every plan, with a fair-use ceiling of 60 times the profiles on your plan, and lists native WhatsApp and LINE as included. SMS volume is custom, billed either through Customer.io or through your own Twilio account. WhatsApp traffic is charged by Meta and Twilio, not by Customer.io.

Brevo covers more of the traditional marketing channels in one place. Prepaid SMS credits are an add-on on every plan, WhatsApp campaigns and transactional WhatsApp need Professional or above, and web push is included on paid plans with targeted-subscriber limits of 1,000 per send on Starter, 10,000 on Standard and 20,000 on Professional. There is also a chat product with its own API. For a B2B SaaS, push to a product audience and in-app messages favour Customer.io, while SMS reminders to prospects favour Brevo's simpler credit model.

What the lower plans leave out

• Customer.io Essentials: no chat support, no managed deliverability, no custom role-based permissions, no anonymous messages, two workspaces, two object types, a monthly plan term, and a premium-integrations category reserved for higher plans.
• Brevo Free: 300 emails a day, one user, automations for up to 2,000 contacts. Starter adds no daily limit but keeps the 2,000-contact automation cap and the Sent by Brevo footer unless you pay for the add-on.
• Brevo Standard: up to three users, one landing page, A/B testing, AI send-time optimization, advanced reports, priority email support, and automation for unlimited contacts.
• Brevo Professional: 10 users, 10 landing pages, one custom object, contact scoring, inbound webhooks, WhatsApp, and phone support, from $499 a month.

Moving from Brevo to Customer.io

1. Export your contacts from Brevo, including attributes and list membership. I did not capture Brevo's current export article, so follow the Export option in the Contacts area, and keep the file of blocked or unsubscribed contacts, which you must not lose.
2. Choose the identifier. Customer.io matches CSV rows on an id, email or phone column. If your product has a user ID, import it as the id so later events line up with the same person.
3. Import people through the CSV importer: files up to 100 MB, roughly one minute for every 20 to 30 thousand rows. Customer.io reserves an unsubscribed attribute, so carry opt-out status in a column of that name, and check the expected format in the guide before the first run.
4. Create company objects and relationships for the accounts your users belong to, then connect your CRM as a source if sales needs the data in segments.
5. Replace each Brevo tracker event with a track call that sends the full payload, and rebuild each workflow with a goal and exit conditions. Brevo's list-based entry points have no direct match, so convert them to segments.
6. Move transactional sends to Customer.io's transactional API last, after sender domains are authenticated, and keep Brevo's plan alive for one billing cycle as a fallback.

Moving from Customer.io to Brevo

1. Decide the email tier first. Add up the maximum emails per month you expect, pick the matching Brevo tier, and make sure its contact ceiling covers your list: 20,000 emails if you hold 5,000 contacts or more.
2. Get your people out of Customer.io through the People view, the API or a warehouse connection. I did not find a CSV export article in the docs I read, so confirm the current route in the app. Event history will not travel in a people file.
3. Import the contacts into Brevo, mapping attributes to Brevo contact attributes, and import opted-out contacts as blocked so they are never mailed.
4. Move events: install the tracker or call the Events API at 10 requests a second, replaying only the events that your new workflows need as triggers. Each call carries the contact's email, so send it with every event.
5. Rebuild workflows in Brevo's editor. Company objects have no Standard-plan equivalent, so store company ID, plan and renewal date as contact attributes.
6. Plan for the 2,000-contact automation cap if you start on Free or Starter, and note that after an upgrade, contacts blocked by that cap enter automatically unless the entry point is added to a list, in which case you must remove and re-add them.