curl --request POST \
  --url https://api.sendkit.dev/emails \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "to": "user@example.com",
  "from": "Your Name <hello@yourdomain.com>",
  "subject": "Welcome to SendKit",
  "html": "<h1>Hello!</h1><p>Welcome aboard.</p>",
  "text": "Hello! Welcome aboard.",
  "cc": [
    "cc@example.com"
  ],
  "bcc": [
    "bcc@example.com"
  ],
  "reply_to": [
    "support@yourdomain.com"
  ],
  "headers": {
    "X-Custom-Header": "value"
  },
  "tags": [
    {
      "name": "campaign",
      "value": "welcome"
    }
  ],
  "scheduled_at": "2026-03-05 10:30:00",
  "attachments": [
    {
      "filename": "invoice.pdf",
      "content": "JVBERi0xLjQKJeLj...",
      "content_type": "application/pdf"
    }
  ],
  "template": {
    "id": "550e8400-e29b-41d4-a716-446655440000",
    "variables": {
      "FIRST_NAME": "John",
      "COMPANY": "Acme Inc"
    }
  }
}
'

import requests

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

payload = {
    "to": "user@example.com",
    "from": "Your Name <hello@yourdomain.com>",
    "subject": "Welcome to SendKit",
    "html": "<h1>Hello!</h1><p>Welcome aboard.</p>",
    "text": "Hello! Welcome aboard.",
    "cc": ["cc@example.com"],
    "bcc": ["bcc@example.com"],
    "reply_to": ["support@yourdomain.com"],
    "headers": { "X-Custom-Header": "value" },
    "tags": [
        {
            "name": "campaign",
            "value": "welcome"
        }
    ],
    "scheduled_at": "2026-03-05 10:30:00",
    "attachments": [
        {
            "filename": "invoice.pdf",
            "content": "JVBERi0xLjQKJeLj...",
            "content_type": "application/pdf"
        }
    ],
    "template": {
        "id": "550e8400-e29b-41d4-a716-446655440000",
        "variables": {
            "FIRST_NAME": "John",
            "COMPANY": "Acme Inc"
        }
    }
}
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({
    to: 'user@example.com',
    from: 'Your Name <hello@yourdomain.com>',
    subject: 'Welcome to SendKit',
    html: '<h1>Hello!</h1><p>Welcome aboard.</p>',
    text: 'Hello! Welcome aboard.',
    cc: ['cc@example.com'],
    bcc: ['bcc@example.com'],
    reply_to: ['support@yourdomain.com'],
    headers: {'X-Custom-Header': 'value'},
    tags: [{name: 'campaign', value: 'welcome'}],
    scheduled_at: '2026-03-05 10:30:00',
    attachments: [
      {
        filename: 'invoice.pdf',
        content: 'JVBERi0xLjQKJeLj...',
        content_type: 'application/pdf'
      }
    ],
    template: {
      id: '550e8400-e29b-41d4-a716-446655440000',
      variables: {FIRST_NAME: 'John', COMPANY: 'Acme Inc'}
    }
  })
};

fetch('https://api.sendkit.dev/emails', 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/emails",
  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([
    'to' => 'user@example.com',
    'from' => 'Your Name <hello@yourdomain.com>',
    'subject' => 'Welcome to SendKit',
    'html' => '<h1>Hello!</h1><p>Welcome aboard.</p>',
    'text' => 'Hello! Welcome aboard.',
    'cc' => [
        'cc@example.com'
    ],
    'bcc' => [
        'bcc@example.com'
    ],
    'reply_to' => [
        'support@yourdomain.com'
    ],
    'headers' => [
        'X-Custom-Header' => 'value'
    ],
    'tags' => [
        [
                'name' => 'campaign',
                'value' => 'welcome'
        ]
    ],
    'scheduled_at' => '2026-03-05 10:30:00',
    'attachments' => [
        [
                'filename' => 'invoice.pdf',
                'content' => 'JVBERi0xLjQKJeLj...',
                'content_type' => 'application/pdf'
        ]
    ],
    'template' => [
        'id' => '550e8400-e29b-41d4-a716-446655440000',
        'variables' => [
                'FIRST_NAME' => 'John',
                'COMPANY' => 'Acme Inc'
        ]
    ]
  ]),
  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/emails"

	payload := strings.NewReader("{\n  \"to\": \"user@example.com\",\n  \"from\": \"Your Name <hello@yourdomain.com>\",\n  \"subject\": \"Welcome to SendKit\",\n  \"html\": \"<h1>Hello!</h1><p>Welcome aboard.</p>\",\n  \"text\": \"Hello! Welcome aboard.\",\n  \"cc\": [\n    \"cc@example.com\"\n  ],\n  \"bcc\": [\n    \"bcc@example.com\"\n  ],\n  \"reply_to\": [\n    \"support@yourdomain.com\"\n  ],\n  \"headers\": {\n    \"X-Custom-Header\": \"value\"\n  },\n  \"tags\": [\n    {\n      \"name\": \"campaign\",\n      \"value\": \"welcome\"\n    }\n  ],\n  \"scheduled_at\": \"2026-03-05 10:30:00\",\n  \"attachments\": [\n    {\n      \"filename\": \"invoice.pdf\",\n      \"content\": \"JVBERi0xLjQKJeLj...\",\n      \"content_type\": \"application/pdf\"\n    }\n  ],\n  \"template\": {\n    \"id\": \"550e8400-e29b-41d4-a716-446655440000\",\n    \"variables\": {\n      \"FIRST_NAME\": \"John\",\n      \"COMPANY\": \"Acme Inc\"\n    }\n  }\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/emails")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"to\": \"user@example.com\",\n  \"from\": \"Your Name <hello@yourdomain.com>\",\n  \"subject\": \"Welcome to SendKit\",\n  \"html\": \"<h1>Hello!</h1><p>Welcome aboard.</p>\",\n  \"text\": \"Hello! Welcome aboard.\",\n  \"cc\": [\n    \"cc@example.com\"\n  ],\n  \"bcc\": [\n    \"bcc@example.com\"\n  ],\n  \"reply_to\": [\n    \"support@yourdomain.com\"\n  ],\n  \"headers\": {\n    \"X-Custom-Header\": \"value\"\n  },\n  \"tags\": [\n    {\n      \"name\": \"campaign\",\n      \"value\": \"welcome\"\n    }\n  ],\n  \"scheduled_at\": \"2026-03-05 10:30:00\",\n  \"attachments\": [\n    {\n      \"filename\": \"invoice.pdf\",\n      \"content\": \"JVBERi0xLjQKJeLj...\",\n      \"content_type\": \"application/pdf\"\n    }\n  ],\n  \"template\": {\n    \"id\": \"550e8400-e29b-41d4-a716-446655440000\",\n    \"variables\": {\n      \"FIRST_NAME\": \"John\",\n      \"COMPANY\": \"Acme Inc\"\n    }\n  }\n}")
  .asString();

require 'uri'
require 'net/http'

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

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  \"to\": \"user@example.com\",\n  \"from\": \"Your Name <hello@yourdomain.com>\",\n  \"subject\": \"Welcome to SendKit\",\n  \"html\": \"<h1>Hello!</h1><p>Welcome aboard.</p>\",\n  \"text\": \"Hello! Welcome aboard.\",\n  \"cc\": [\n    \"cc@example.com\"\n  ],\n  \"bcc\": [\n    \"bcc@example.com\"\n  ],\n  \"reply_to\": [\n    \"support@yourdomain.com\"\n  ],\n  \"headers\": {\n    \"X-Custom-Header\": \"value\"\n  },\n  \"tags\": [\n    {\n      \"name\": \"campaign\",\n      \"value\": \"welcome\"\n    }\n  ],\n  \"scheduled_at\": \"2026-03-05 10:30:00\",\n  \"attachments\": [\n    {\n      \"filename\": \"invoice.pdf\",\n      \"content\": \"JVBERi0xLjQKJeLj...\",\n      \"content_type\": \"application/pdf\"\n    }\n  ],\n  \"template\": {\n    \"id\": \"550e8400-e29b-41d4-a716-446655440000\",\n    \"variables\": {\n      \"FIRST_NAME\": \"John\",\n      \"COMPANY\": \"Acme Inc\"\n    }\n  }\n}"

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

{
  "id": "550e8400-e29b-41d4-a716-446655440000"
}

{
  "name": "validation_error",
  "message": "Invalid API key."
}

{
  "name": "validation_error",
  "message": "The from address domain is not verified."
}

{
  "name": "rate_limit_exceeded",
  "message": "Rate limit exceeded. Please retry after 30 seconds."
}