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POST
/
properties
Create a property
curl --request POST \
  --url https://api.sendkit.dev/properties \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "key": "company",
  "type": "string",
  "fallback_value": "N/A"
}
'
import requests

url = "https://api.sendkit.dev/properties"

payload = {
"key": "company",
"type": "string",
"fallback_value": "N/A"
}
headers = {
"Authorization": "Bearer <token>",
"Content-Type": "application/json"
}

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

print(response.text)
const options = {
method: 'POST',
headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
body: JSON.stringify({key: 'company', type: 'string', fallback_value: 'N/A'})
};

fetch('https://api.sendkit.dev/properties', options)
.then(res => res.json())
.then(res => console.log(res))
.catch(err => console.error(err));
<?php

$curl = curl_init();

curl_setopt_array($curl, [
CURLOPT_URL => "https://api.sendkit.dev/properties",
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([
'key' => 'company',
'type' => 'string',
'fallback_value' => 'N/A'
]),
CURLOPT_HTTPHEADER => [
"Authorization: Bearer <token>",
"Content-Type: application/json"
],
]);

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

curl_close($curl);

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

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

func main() {

url := "https://api.sendkit.dev/properties"

payload := strings.NewReader("{\n \"key\": \"company\",\n \"type\": \"string\",\n \"fallback_value\": \"N/A\"\n}")

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

req.Header.Add("Authorization", "Bearer <token>")
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))

}
HttpResponse<String> response = Unirest.post("https://api.sendkit.dev/properties")
.header("Authorization", "Bearer <token>")
.header("Content-Type", "application/json")
.body("{\n \"key\": \"company\",\n \"type\": \"string\",\n \"fallback_value\": \"N/A\"\n}")
.asString();
require 'uri'
require 'net/http'

url = URI("https://api.sendkit.dev/properties")

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

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n \"key\": \"company\",\n \"type\": \"string\",\n \"fallback_value\": \"N/A\"\n}"

response = http.request(request)
puts response.read_body
{
  "id": "550e8400-e29b-41d4-a716-446655440000",
  "key": "company",
  "type": "string",
  "fallback_value": "N/A",
  "created_at": "2026-03-03 10:00:00",
  "updated_at": "2026-03-03 10:00:00"
}
{
"message": "Invalid API key."
}
{
"message": "The email field is required."
}

Authorizations

Authorization
string
header
required

API key from your SendKit dashboard. Pass it as a Bearer token in the Authorization header.

Body

application/json
key
string
required

The property key. Must be unique per team.

Maximum string length: 255
Example:

"company"

type
enum<string>
required

The data type of the property.

Available options:
string,
number,
date
Example:

"string"

fallback_value
string | null

Default value used when a contact doesn't have this property set.

Maximum string length: 1000
Example:

"N/A"

Response

Property created successfully

id
string<uuid>

Unique identifier.

Example:

"550e8400-e29b-41d4-a716-446655440000"

key
string

The property key. Used when setting values on contacts.

Example:

"company"

type
enum<string>

The data type of the property.

Available options:
string,
number,
date
Example:

"string"

fallback_value
string | null

Default value used when a contact doesn't have this property set.

Example:

"N/A"

created_at
string<date-time>

When the property was created.

Example:

"2026-03-03 10:00:00"

updated_at
string<date-time>

When the property was last updated.

Example:

"2026-03-03 10:00:00"