Customer.io Form Builder — Capture & Track

Why build Customer.io forms in ConvertFlow

Customer.io is built for people comfortable with data — attributes, events, segments, and campaigns triggered by all three. What it doesn't give you is a way to collect that data from your website without writing code.

That's the gap. ConvertFlow forms create and update Customer.io people, write attributes, and track events — the same API surface a developer would call, from a visual builder. A form submission can describe the person and start the campaign in one action.

1. Connect Customer.io to ConvertFlow

Head to your ConvertFlow website's Integrations area and click to connect with Customer.io.

In Customer.io, go to Settings → Integrations → Manage API Credentials to find your site ID, tracking key and app API key.

Three credentials — more than any other ConvertFlow integration — and the reason is worth understanding rather than just copying.

The tracking API key and the App API key are separate keys with separate permissions, created on separate screens. They are not interchangeable, and pasting one where the other belongs is the most common reason this step fails.

Pro tip: create both a tracking key and an app key specifically for ConvertFlow rather than reusing existing ones. If you ever need to rotate or revoke access, you can do it without breaking anything else that touches your Customer.io account.

Then copy all three into ConvertFlow's integration fields.

Customer.io and ConvertFlow are now connected, and ConvertFlow starts pulling in your account data.

2. Add a form to your campaign

Add your Customer.io form to a ConvertFlow landing page, popup or embed. Click to add an element and choose the "form" element type — start from a form template or build from scratch.

3. Toggle the contact fields you want

Select the form element and switch on the contact fields to request. Email address maps to Customer.io automatically.

Each field can be edited from the builder panel — placeholder text, label, required state and more.

4. Verify emails and phone numbers

ConvertFlow can check that an entered address exists with its provider before the person reaches Customer.io, which protects deliverability and keeps invalid addresses out of your billable profile count. Phone verification formats numbers to the international E.164 standard — useful if you send SMS or push from Customer.io.

5. Add consent checkboxes

Scroll below the preset contact fields to find compliance checkboxes:

• Privacy consent: link to your privacy policy and terms of service alongside a required checkbox.
• Marketing consent: if your form gates content but also opts the person into ongoing marketing, collect consent for it.
• SMS consent: require consent to SMS marketing with the required disclosures.

6. Add custom fields and map them to Customer.io attributes

By clicking to add a field at the end of the fields list, you can add as many custom fields as you'd like.

Customer.io works differently from most integrations here. Rather than picking from a dropdown of existing fields, you write the attribute's data name directly.

That's more flexible — you don't need to pre-create anything, since Customer.io accepts attributes on write. It also means there's no autocomplete to catch a typo. Write skin_type on one form and skinType on another and you now have two attributes holding half your data each, with no error to tell you.

Pick a naming convention before you build your second form, and keep a note of it.

Choose the field type — text, dropdown, radio selection, paragraph or hidden. Dropdown and radio options can carry score values for funnel logic.

7. Map survey and quiz answers to attributes

Survey and quiz elements have a "Map to custom field" dropdown for selecting the Customer.io attribute each answer writes to.

8. Map ConvertFlow's preset fields to Customer.io

With Customer.io connected, your Integrations page shows a Fields button. Use it to map ConvertFlow's preset contact fields to Customer.io attributes by entering each attribute's data name. Email address is already mapped.

9. Style the form to match your site

In the Design tab, set spacing, field layout, width, fonts, button colour and roundness, field colour and shadows.

10. Add Customer.io automations on submit

In the Actions tab, choose what follows submission — redirect to a URL, jump to another funnel step, display a thank-you message, or open a popup.

Alongside it, add Customer.io automations. Four types are available:

• Update attribute value — write a value to an attribute on the person
• Track an event — record a named event against them
• Add to manual segment
• Remove from manual segment

Track an event is the one worth understanding. Customer.io campaigns trigger on events, so tracking one at the moment of submission starts the campaign directly — no segment membership to wait for, no daily sync. You just write the event name.

Remove from manual segment is rarer still, and genuinely useful: a form submission can take someone out of a segment as well as put them in. Someone who fills in your "already a customer" form can be pulled out of the prospect nurture immediately, rather than continuing to receive it until the next sync corrects itself.

These automations can be triggered by form submissions, survey selections, button clicks, conditional funnel outcomes and page visits — not just forms.

Conditional actions let you route by field value, so a high-intent answer tracks a different event than a browser.

11. Report on submissions

The funnel breakdown report shows how many people saw, converted and completed the form, where they dropped off, and which answers they selected.

12. Segment and personalize for Customer.io people

Once attributes and events are landing on Customer.io profiles, build segments from them and target your campaigns accordingly.

ConvertFlow can also read your Customer.io segments and personalize your website for them — so an existing person sees something other than the same capture form.

13. Publish

• On Shopify: publish to a Shopify page in one click.
• On WordPress: add ConvertFlow's snippet once, then target the form to specific posts, pages or categories.
• Anywhere else: Webflow, Squarespace, Wix or any CMS take the same single embed snippet.