Anticode Open builder

Website signup form to Kit: new subscribers straight into your form

Anticode's Kit connector subscribes each newsletter sign-up from your published sites to one Kit form, which means they also enter whatever sequences and automations that form starts. It needs a Kit V3 API key and the form's number. Kit no longer issues V3 keys for new integrations, so check your Kit account offers one before you plan around it. Bookings, contact messages and invite requests are never sent to Kit.

Updated · By the Anticode team

Why subscribe through a Kit form

In Kit, a form is more than a box on a page: it's an entry point that can tag people, start a welcome sequence and trigger visual automations. Connecting a website signup form to Kit by form number means the newsletter box on your Anticode site feeds the same form Kit's own embed would, without loading Kit's script on a page that runs none. Subscribers show up in Kit as having joined through that form, so you can measure it separately from your other entry points.

What Anticode sends

For each newsletter sign-up, Anticode's server calls Kit's API at api.convertkit.com to subscribe the address to your form. The built-in newsletter form asks only for an email, so that's normally all that's sent. If a sign-up does carry a name field, its first 80 characters go to Kit as the subscriber's first name. The address is checked and lower-cased first; a sign-up without a valid email is skipped.

Kit, formerly ConvertKit, documents this endpoint in its V3 API reference. Kit describes V3 as no longer in active development and offers a newer V4 API; the connector uses V3 and its API key. Kit doesn't create V3 keys for new integrations, so a newer Kit account may not have one to give. Look for it before relying on this connector; if there isn't one, send sign-ups through the webhook connector to an automation tool that connects to Kit instead.

Find the two values

API key
In Kit, open Settings › Developer. Kit's authentication page puts it under the V3 Key section, next to an API secret. Anticode needs the API key, not the secret. If your account shows no V3 key, this connector won't work for it.
Form number
Open the form in Kit and look at the address bar. The run of digits in the URL is the form's number, such as 1234567.

Connect and verify

  1. In Anticode's dashboard, open Connectors › Kit, fill in API key and Form number, and press Save and turn on.
  2. Press Check the connection. It asks Kit to list your forms with that key, which proves the key works without subscribing anybody.
  3. The check doesn't confirm the form number belongs to one of those forms. So sign up once through your live site with an address you own, and look for it in the Kit form's subscribers.
  4. If the form has a sequence, confirm the first email arrives.

Confirmation emails

Whether a new subscriber must confirm before they're active is a setting on the Kit form itself, not something Anticode controls. If the form asks for confirmation, Kit sends its own email and the subscriber stays unconfirmed until they click. Edit that email's wording in Kit so it names your newsletter and matches your site; people who don't recognise it won't click. This differs from the Mailchimp connector, where Anticode always requests double opt-in.

Credentials stay sealed

  • The API key and form number are stored together, encrypted with AES-256-GCM and bound to your account and this connector.
  • They're never shown again in the dashboard, and never placed in the builder or your published pages. To change either, enter both.
  • The key is used only on Anticode's server, only to reach Kit's API.
  • If it leaks, regenerate it in Kit's developer settings and enter the new one.

Limits

  • Sign-ups only. People who book or send a message aren't added, so your list stays made of people who asked to join.
  • No tags or custom fields beyond the form's own automations. Tag through the form's rules in Kit.
  • One form per account. Every site you publish feeds the same Kit form.
  • Sent once, without retries, about a minute after the sign-up. If Kit is unavailable, the sign-up stays in your Anticode Submissions to add by hand.
  • Held sign-ups past a free site's monthly allowance aren't sent.

Troubleshooting

  • No V3 key in Kit. Kit doesn't create V3 keys for new integrations, and the connector can't use a V4 key. Use the webhook connector and an automation tool instead.
  • Check passes, nobody arrives. The form number is probably wrong. Copy it from the form's URL again.
  • Kit answered 401. The key was regenerated or mistyped; paste the current one.
  • Subscribers are unconfirmed. The form requires confirmation; they need to click Kit's email.
  • Contact-form senders are missing. That's intended. Only newsletter sign-ups go to Kit.

Questions people ask

Is this the same as ConvertKit?

Yes. ConvertKit renamed itself Kit; the API address still uses the convertkit.com name.

Can I use Kit's own embed instead?

Not on design-engine pages, which run no scripts and allow no embeds. The connector does the same job server-side.

Can sign-ups go to a Kit tag rather than a form?

No, the connector subscribes to a form. Add a rule on that form to apply the tag.

Sources

  1. Kit Developers: API V3, checked
  2. Kit Developers: V3 authentication, checked