curl --request POST \
  --url https://api.kit.com/v4/webhooks \
  --header 'Content-Type: application/json' \
  --header 'X-Kit-Api-Key: <api-key>' \
  --data '
{
  "target_url": "https://example.convertkit.dev/",
  "event": {
    "name": "subscriber.subscriber_activate",
    "form_id": null,
    "tag_id": null,
    "sequence_id": null,
    "product_id": null,
    "initiator_value": null,
    "custom_field_id": null
  }
}
'

require 'uri'
require 'net/http'

url = URI("https://api.kit.com/v4/webhooks")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["X-Kit-Api-Key"] = '<api-key>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"target_url\": \"https://example.convertkit.dev/\",\n  \"event\": {\n    \"name\": \"subscriber.subscriber_activate\",\n    \"form_id\": null,\n    \"tag_id\": null,\n    \"sequence_id\": null,\n    \"product_id\": null,\n    \"initiator_value\": null,\n    \"custom_field_id\": null\n  }\n}"

response = http.request(request)
puts response.read_body

const options = {
  method: 'POST',
  headers: {'X-Kit-Api-Key': '<api-key>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    target_url: 'https://example.convertkit.dev/',
    event: {
      name: 'subscriber.subscriber_activate',
      form_id: null,
      tag_id: null,
      sequence_id: null,
      product_id: null,
      initiator_value: null,
      custom_field_id: null
    }
  })
};

fetch('https://api.kit.com/v4/webhooks', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://api.kit.com/v4/webhooks"

	payload := strings.NewReader("{\n  \"target_url\": \"https://example.convertkit.dev/\",\n  \"event\": {\n    \"name\": \"subscriber.subscriber_activate\",\n    \"form_id\": null,\n    \"tag_id\": null,\n    \"sequence_id\": null,\n    \"product_id\": null,\n    \"initiator_value\": null,\n    \"custom_field_id\": null\n  }\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("X-Kit-Api-Key", "<api-key>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.kit.com/v4/webhooks",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'target_url' => 'https://example.convertkit.dev/',
    'event' => [
        'name' => 'subscriber.subscriber_activate',
        'form_id' => null,
        'tag_id' => null,
        'sequence_id' => null,
        'product_id' => null,
        'initiator_value' => null,
        'custom_field_id' => null
    ]
  ]),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/json",
    "X-Kit-Api-Key: <api-key>"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

import requests

url = "https://api.kit.com/v4/webhooks"

payload = {
    "target_url": "https://example.convertkit.dev/",
    "event": {
        "name": "subscriber.subscriber_activate",
        "form_id": None,
        "tag_id": None,
        "sequence_id": None,
        "product_id": None,
        "initiator_value": None,
        "custom_field_id": None
    }
}
headers = {
    "X-Kit-Api-Key": "<api-key>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

{
  "webhook": {
    "id": 9,
    "account_id": 1788,
    "event": {
      "name": "subscriber_activate",
      "initiator_value": null
    },
    "target_url": "https://example.convertkit.dev/"
  }
}

{
  "errors": [
    "The access token is invalid"
  ]
}

{
  "errors": [
    "`event` and `target` parameters must be provided"
  ]
}