Using the API to Subscribe a Contact to a List

  • 6 May 2022
  • 7 replies

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  • Contributor II
  • 4 replies

Hi there, below is the code we use to add a new email to our Klaviyo account. What do we need to change to get them added to a certain list? The API docs are a little over our heads.


var _learnq = _learnq || [];

  _learnq.push(['identify', {

    ‘$email’ :,

    ‘$source’: footer




<script type="application/javascript" async src=""></script>


Best answer by Dov 9 May 2022, 15:26

View original

7 replies

Userlevel 7
Badge +61

Hi @smp,

Thanks for sharing this question with the Klaviyo community.

I’m afraid you cannot use an identify call to subscribe a user to a specific list. Instead, you should be using the subscribe endpoint:{list_id}/subscribe. After this request is made, by default, the user being subscribed will receive a double opt-in email asking them to confirm their subscription. Once confirmed, they will be added to the list specified in the call. We have an example request in our API documentation on that here.

Also keep in mind, there are plenty of other ways to subscribe users to lists in Klaviyo. Including adding them via a .csv file. This is ideal if you have a lot of users to add to a list at once. Or, you can quick add users to a list, an ideal method if you only have a handful of users you’d like to add to a list. And of course, using Klaviyo sign-up forms or a subscribe page.

I hope that’s helpful.  


Badge +2

Hi there, I used the API sample on my site: I replaced the APIKEYHERE with our actual api key in the live code.

const options = {
method: 'POST',
headers: {Accept: 'application/json', 'Content-Type': 'application/json'},
body: JSON.stringify({profiles: [{email: ''}]})

fetch('', options)
.then(response => response.json())
.then(response => console.log(response))
.catch(err => console.error(err));

But it generates these errors in the console:

Access to fetch at '' from origin '' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.

(anonymous) @ VM3562:1
(anonymous) @ b77.php:7571

TypeError: Failed to fetch
    at <anonymous>:1:876
    at b77.php:7571:1

Userlevel 7
Badge +61

Hi @smp,

Thanks for sharing this question with the Klaviyo community.

The endpoint you are trying to use is server-side only which is why you're receiving the CORS error. If you are making this request client-side, instead utilize this client-side endpoint:

var settings = {
"async": true,
"crossDomain": true,
"url": "",
"method": "POST",
"headers": {
"content-type": "application/x-www-form-urlencoded",
"cache-control": "no-cache"
"data": {
"g": "LIST_ID", // replace LIST_ID with id of list to be subscribed
"email": email,
// pass in additional fields, each additional field
// must be included in the $fields string separated by commas
"$fields": "$source, $first_name, $last_name",
"$source": "Account Creation",
"$first_name": firstname,
"$last_name": lastname
$.ajax(settings).done(function(response) {

I hope this helps and thanks for being a member of our community.

Badge +1

Hi Dob,

Question about your original response to this post.

Why did you suggest using{list_id}/subscribe

and not{list_id}/members


I guess my question is what is the difference between the subscribe endpoint and the members endpoint. Both of them appear to be adding a customer to a list.

Thank you in advance,


Userlevel 7
Badge +61

Hi @chemahad,

Thanks for your question.

/subscribe: Subscribes profiles to a list. Profiles will be subject to the single or double opt-in process in accordance with that list’s opt-in settings. If you have double opt-in turned on (which is the default setting for Klaviyo lists), users will not be added to the list until they confirm their subscription via the double opt-in email.

 /members: Adds profiles to a list. This endpoint is functionally equivalent to adding profiles to a list via a CSV upload and will immediately add profiles to the list without the opt-in requirement. 

The subscribe endpoint is recommended because the double opt-in process helps you grow your list while also minimizing abuse and preventing the accumulation of invalid or mistyped emails and phone numbers. Additionally, carriers often require double opt-in for SMS.

I hope that’s helpful.

Badge +1

@Dov How are we supposed to call the endpoint which is server-side only when using Shopify? Is it necessary to create a custom Shopify app to call the Klaviyo endpoint from the server? 

Userlevel 7
Badge +61

Hi @phillip,

Thanks for your post.

It’s not necessary to create a custom app - you can use a tool like Postman to send the API call server-side. You could also use a cURL request using the terminal like the following:

curl --request POST \
--url '' \
--header 'accept: application/json' \
--header 'content-type: application/json' \
--data '
"profiles": [
"email": ""

If you’re looking to automate this process, you would need to build our own rest API to handle the server side calls.

I hope that’s helpful.