Customer.io vs ConvertKit: messaging driven by product data, or by an audience you own

The bill at four list sizes

Kit's figures are the monthly equivalents under its yearly-billing toggle and Customer.io's are Essentials readouts at monthly billing, both from 7 October 2026. Customer.io's published entry price is for 5,000 profiles, so the 1,000 row uses that figure.

Annualised, the 5,000-contact gap is $300 (25 times 12), the 10,000 gap is $348 (29 times 12), and the entry-level gap at 1,000 is $804 (67 times 12). Kit Pro, with unlimited users and subscriber signals, is $13 above Customer.io at 10,000 (158 minus 145), so Customer.io is the cheaper of the two once you need Kit's top plan. For a pure broadcast newsletter, Kit Free means the comparison is $0 against $100.

How each one models your audience

Customer.io's profiles are people and objects, and the Essentials card lists 5k profiles, two object types, a visual workflow builder, an AI agent with core execution skills, email and community support and basic data integrations. Objects let a company or workspace exist as its own record, which matters for B2B software where the message may depend on the account. They are also billed. Ten thousand users in 2,000 company objects is 12,000 profiles, and at the page's $0.009 per additional profile that is $145 plus $18, or $163 a month, before any email overage of $0.12 per extra 1,000 beyond the included million. Its billing docs also count a profile for the month if it existed at any point in it, deletions included.

Kit models subscribers with tags, custom fields, forms and purchases. Free covers unlimited landing pages, forms and broadcasts, tagging and segmentation, and selling digital products and subscriptions. Creator adds unlimited Visual Automations and sequences, A/B subject lines and branding removal, and Pro adds unlimited users, subscriber signals, deliverability reporting and a referral system. A subscriber is one email address with attributes. Kit's pricing page does not list company-level records.

Support, volume and what the top plans add

• Support. Kit lists 24/7 email and chat support on Creator. Customer.io Essentials lists email and community support, and its Premium card adds premium chat and email support, 90-day onboarding support and daily routines for scheduled tasks.
• Sending volume. Kit's pricing page shows unlimited broadcasts on Free and unlimited sequences on Creator, with no send count attached. Customer.io Essentials includes 1 million emails a month.
• Compliance. Customer.io's Premium card lists HIPAA compliance, and its pricing table lists US and EU data centers on every plan. Kit's data processing page sat behind a CAPTCHA when I tried to read it on 7 October 2026, so ask Kit directly if your contracts need a DPA.
• Channels. Kit's Creator plan lists SMS marketing. Customer.io lists email, push, in-app messaging and WhatsApp among its features, with SMS volume custom on its displayed plans.

What happens when a card fails

With Customer.io, Stripe sends invoice.payment_failed to a webhook endpoint you registered. Its Stripe guide sets that endpoint to a webhook-triggered automation, finds the person by email, and names dunning on that event as a use. The automation can then send a card-update message with the amount and attempt number as event properties, and a later invoice.paid event can exit the person from the journey. The event trigger accepts back-dated events up to 72 hours old, which helps when your handler retries after an outage.

With Kit, the Stripe app records purchases and subscriptions and does not support refunds, and Kit's troubleshooting article names charge succeeded and subscription updated as the events it watches. Whether Stripe's past-due state reaches Kit through a subscription update is worth testing in Stripe's test mode before you rely on it; the dependable route is your own server tagging the subscriber through Kit's API when it receives the failed-invoice event. Stripe's own customer emails, which include a card-update link, can also carry the message while Kit handles the rest.

Moving from one to the other

1. Export subscribers with tags and fields. Import unsubscribed addresses as unsubscribed.
2. Kit's pricing page advertises free migrations into Kit. Moving to Customer.io, choose the profile ID deliberately, since a webhook-triggered automation can match on email but later events are cleaner against a stable user ID.
3. Rebuild sequences as journeys one at a time and keep the old ones running for one cycle on a small cohort.
4. Add the new account's DKIM and SPF before any send, and consider Customer.io's EU data center option if your users are in Europe.

Which to choose

• Kit fits writers, educators and founders whose list is an audience, especially below 10,000 subscribers where broadcasts cost nothing.
• Customer.io fits a software company with accounts, trials and billing events driving messages, and a need for transactional mail inside the same tool.
• Both is a sensible split for a product with a public newsletter: Kit for subscribers who opted in on the blog, Customer.io for people who signed up for the app.

Related reading: all comparisons, Loops vs ConvertKit, Loops vs Customer.io, MailerLite vs ConvertKit, ConvertKit vs Drip and the user onboarding tools guide.