Server-to-Server (S2S) Measurement

Advanced measurement where you send data directly from your server to the Sklik endpoint.

S2S is suitable for websites where you need maximum accuracy without relying on third-party cookies. It can also be used for measuring conversions from mobile applications or for sending offline conversions.

Prerequisites

• Frontend script deployed on all pages of the website (generates cookies sid and udid)
• Ability to read cookies sid and udid from the server
• Ability to hash personal data with SHA-256 on the server
• SEM ID for S2S – a special identifier used exclusively for S2S measurement. It differs from the standard SEM ID (for the script and GTM). See Where to find SEM ID? If you have Seznam Shopping store outlets, each outlet has its own SEM ID for S2S.

Endpoint

Send all S2S requests as POST to:

POST https://sem.seznam.cz/rtgconv
Content-Type: application/json

HTTP headers

User identification

The S2S payload must contain the sid and udid cookies generated by the frontend script. Read them on the frontend and pass them to the server, where you include them in the user_ids.user_data object.

function getCookie(name) {
  const match = document.cookie.match(new RegExp('(?:^|; )' + name + '=([^;]*)'));
  return match ? decodeURIComponent(match[1]) : null;
}

const sid  = getCookie('sid');   // pass to server as user_ids.user_data.sid
const udid = getCookie('udid');  // pass to server as user_ids.user_data.udid

Another key identifier is sznaiid – the click ID from Sklik. This value is found in the URL parameter after a click on an ad and is used for anonymous conversion modelling. It can be safely stored on the server without user consent.

Payload structure

user_ids.user_data object

Special parameters in event_data for S2S

Complete payload example

{
  "schema_version": "v2",
  "event_source": "web",
  "event_name": "Purchase",
  "event_type": "rtgconv",
  "event_time": 1770134113676,
  "event_id": "018e4f2a-1234-7abc-9def-0123456789ab",
  "event_url": "https://vas-eshop.cz/dekujeme",

  "user_ids": {
    "user_data": {
      // Cookies from sul.js – read from browser (do not hash)
      "sid": "id=1922397029101872874|t=1737450723.526|te=1756971615.061|c=0F247CCA",
      "udid": "01958f34-71d5-7ec2-ae01-cb3c80a1d0a0",

      // Personal data – hash with SHA-256 on the server
      "em": "6db68d052788e70eb459463eb34370fe983ef838db65641902f02326fabc37a7",
      "ph": "ca6faa7abf120a739e8ce3bcf581553af9ad983b3290ed8cdf8cc40b9d4fefcf",
      "fn": "6a0ac0fd972c325d6ca5512b67a5e0ad996c4a3e9b59971d125164e6d4db1a1c",
      "ln": "64118260ecb916c23621d8f2768d8dc75d1f5710b1b7e4f2c41ad41e6bc4d688",
      "ct": "f377db9f1f0af132866afd5c4381512a5c9a3b3a32e9ca2f88f0aced18264568"
    }
  },

  "consent_mode": {
    "ad_storage": "granted",
    "ad_user_data": "granted",
    "ad_personalization": "granted",
    "functionality_storage": "denied",
    "analytics_storage": "denied"
  },

  "s2s_headers": {
    "client_ip_address": "77.75.74.172",
    "user_agent": "Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36...",
    "sec_ch_ua_mobile": "?0",
    "sec_ch_ua_platform": "\"Windows\""
  },

  "event_data": {
    "sem_id": "VASE_SEM_ID_PRO_S2S",
    "sznaiid": "2627214859780792651",
    "order_id": "OBJ-987654",
    "content_type": "product",
    "currency": "CZK",  // only CZK is supported
    "value": 27364,          // total value excluding VAT (in CZK)
    "value_tax": 5746,
    "delivery_type": "CESKA_POSTA",
    "delivery_price": 121,       // including VAT
    "other_costs": -500,         // discount including VAT
    "payment_type": "karta",
    "contents": [
      {
        "id": "ABC12345",
        "quantity": 1,
        "unit_price": 33490,       // including VAT
        "content_name": "iPhone 15 Pro Max",
        "content_category": "Elektronika | Mobilní telefony | Apple"
      }
    ]
  }
}

Sending the request

Send the payload as an HTTP POST request to the endpoint https://sem.seznam.cz/rtgconv with the Content-Type: application/json header.

curl -X POST https://sem.seznam.cz/rtgconv \
  -H "Content-Type: application/json" \
  -H "X-Client-Id: my-eshop-plugin" \
  -H "X-Client-Version: 1.0.0" \
  -d '{ ... your payload ... }'

await fetch('https://sem.seznam.cz/rtgconv', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
    'X-Client-Id': 'my-eshop-plugin',
    'X-Client-Version': '1.0.0',
  },
  body: JSON.stringify(payload)
});

import requests

response = requests.post(
    'https://sem.seznam.cz/rtgconv',
    json=payload,
    headers={
        'X-Client-Id': 'vas-eshop-plugin',
        'X-Client-Version': '1.0.0',
    }
)
response.raise_for_status()

Error handling and recommendations