This article explains why Wunderkind Server-Side Tracking (SST) is important, how it addresses iOS 26 tracking protections, what it means for privacy and cookies, and how to implement SST end‑to‑end.

Table of Contents

• What is Server-Side Tracking?
• Why iOS 26 is a problem for Wunderkind
• Measuring the impact: example client data
• How SST and first-party domains solve this
  • First-party tracking domain for Wunderkind
  • First-party domain for your tag manager
  • Cookie behavior, “Host Only” controls, and privacy
• Requirements and eligibility
• Implementation steps
  • Step 1: Set up a first-party tracking subdomain (DNS / CNAME)
  • Step 2: Enable Server-Side Tracking in Wunderkind Platform
  • Step 3: Update your Wunderkind tag URL to use the new subdomain
  • Step 4: Validate and launch
• Shopify App: automatic deployment of your new domain
• FAQ: Privacy, cookies, and consent

What is Server-Side Tracking?

Server-Side Tracking (SST) routes key parts of Wunderkind’s tracking through your own first‑party subdomain, proxied to Wunderkind’s infrastructure. Instead of loading from a traditional third‑party domain, your Wunderkind tag and API calls are delivered from a hostname on your site (for example, wd.yourdomain.com) and then forwarded securely to Wunderkind’s servers.

This setup:

• Makes Wunderkind appear as first‑party to your site and your users’ browsers.
• Helps maintain reliable session continuity, especially on Safari/iOS.
• Keeps the same campaigns, logic, and experiences you run today — the change is purely infrastructural.

Why iOS 26 is a problem for 3rd party tags like Wunderkind’s

Apple’s iOS 26 update expanded tracking protections in Safari. In some cases, Safari now blocks third‑party tracking domains entirely, which can prevent the Wunderkind tag from loading and lead to fewer sessions tracked on iOS Safari.

Concretely, when Safari blocks the third‑party domain that serves the Wunderkind tag:

• The tag never loads for affected users.
• If not tag loads, no catalog or abandonment triggers can send an email
• No campaigns can trigger from visits in iOS26 Safari

Measuring the impact: example client data

To illustrate the effect, consider an example client:

• Between October – January when iOS26 was installed slowly by users, the average ratio of Wunderkind visits to GA4 visits was 67%.
• Between February – March that average ratio rose to 90% likely due to GA4 now being blocked.  Now both Wunderkind and GA couldn’t see iOS26 traffic.
• This implies that, prior to the change, Wunderkind was missing roughly 25% of visits because Safari was blocking our tag.

How SST and first-party domains solve this

At a high level, the fix has two parts:

1. First‑party delivery of the Wunderkind tag

• Wunderkind loads from a subdomain of your site (e.g., wd.yourdomain.com) instead of a third‑party domain such as tag.bounceexchange.com or tag.wknd.ai.
• From Safari’s perspective, the tag is now part of your site, not a third‑party tracker.

2. Server-Side Tracking (SST) for durable session continuity

• SST ensures that key session and identification logic continues to work even as browser protections evolve.
• Wunderkind makes note of 1st party cookies server side so that even if 1st party cookies expire, we can re-set the cookie for re-identification
• No changes are required to your campaigns, strategy, or onsite experiences; those continue to run as‑is.

First-party tracking domain for Wunderkind

You’ll configure a dedicated subdomain (commonly wd.yourdomain.com) and point it to Wunderkind via a CNAME record:

• For example, create wd.yourdomain.com → cdnwd.com in your DNS provider.
• Wunderkind then serves the tag and related assets from that first‑party subdomain.

This is the core requirement for SST and first‑party tracking.

Figure 1 shows a typical DNS configuration once the CNAME is in place:

Figure 1: Example DNS configuration for a proxied SST subdomain (e.g., wd.yourdomain.com).

First-party domain for your tag manager

If the Wunderkind tag with SST is firing through a tag manager, the tag manager must also be using a 1st‑party domain to avoid Safari classifying it as third‑party again.  Otherwise Wunderkind’s tag (and all tags within it) will be blocked in iOS26 Safari.

• For Google Tag Manager’s server-side gateway, use a subdomain such as gtm.yourdomain.com and configure it in your DNS and GTM settings.
• For Tealium, enable First-Party Domains and map a subdomain like tags.yourdomain.com via the CNAME records Tealium provides.

Cookie behavior, “Host Only” controls, and privacy

With SST and a first‑party domain:

• Wunderkind only reads the first‑party cookies that Wunderkind sets on your domain, used for identification and session continuity.  However, all 1st party cookies will be sent on the request because of how cookies work.
• Wunderkind does not read or exfiltrate other first‑party cookies set by your site or other vendors.
• You can further harden this by using browser‑level “Host Only” cookie controls (and related attributes like Domain, Path, and SameSite) so that certain cookies:
  • Are only readable on the exact host that set them, and
  • Are not shared across subdomains.

This means you retain full control over which cookies are visible where, and Wunderkind remains limited to its own identifiers operating as part of your site.

From a privacy/consent perspective:

• SST does not change the types of data Wunderkind collects; it changes how reliably we can capture the same behavioral signals you already rely on.
• Your existing Consent Management Platform (CMP) and consent flows continue to govern whether the Wunderkind tag is allowed to run.

Requirements and eligibility

To use Wunderkind SST and first‑party tracking, you’ll need:

• A domain where you can create a new subdomain (e.g., wd.yourdomain.com).
• Access to your DNS provider (Cloudflare or any standard DNS host).
• Ability to make changes in the Wunderkind Autonomous Marketing Platform under Settings → Identification.
• (Optional but recommended) Ability to configure your tag manager to use a first‑party domain (e.g., GTM Server-side Gateway, Tealium First-Party Domains).

If you use the Wunderkind Shopify App for onsite tracking, additional automation is available — see Shopify App: automatic deployment below.

Implementation steps

Step 1: Set up a first-party tracking subdomain (DNS / CNAME)

If your site is not hosted on Cloudflare

1. Log in to your DNS provider (e.g., Cloudflare, Route 53, GoDaddy).
2. Go to the DNS settings for your domain.
3. Click Add Record.
4. For Type, select CNAME.
5. For Name, enter your desired subdomain, typically wd (example: wd.clientsite.com).
6. For Target, enter cdnwd.com.
7. Save the record.

If your site is hosted on Cloudflare

1. Log in to Cloudflare and choose your account and domain.
2. Navigate to DNS.
3. Click Add Record.
4. For Type, select CNAME.
5. For Name, use wd (e.g., wd.clientsite.com).
6. For Target, enter cdnwd.com.
7. Ensure Proxy Status is enabled (Proxied).
8. (Optional) Add a comment for future reference.
9. Save the record.

Use the dig or nslookup commands to confirm that the new subdomain resolves correctly:

• Mac/Linux: dig wd.example.com +short
• Windows: nslookup wd.example.com

You should see either the CNAME target (cdnwd.com) and its IPs, or just the IPs if proxied via Cloudflare.

Step 2: Enable Server-Side Tracking in Wunderkind Platform

Next, tell Wunderkind which subdomain to use and enable SST.

1. Log in to the Wunderkind Autonomous Marketing Platform.
2. Navigate to Settings → Identification.
3. On the Identity Graph tab:
   • In Domain name, enter your SST subdomain, e.g., wd.website.com.
   • Toggle Server-side Tracking to On.
   • Click Save.

You’ll see a progress message while SST is enabled (typically 5–10 minutes). Once complete, the toggle shows Complete and a confirmation banner appears.

Figure 2 shows the Identity Graph configuration screen with SST enabled:

Figure 2: Identity Graph configuration with wd.website.com and Server-Side Tracking enabled.

Figure 3 shows the “setup complete” indicator after SST is enabled:

Figure 3: Confirmation message and “Complete” status once SST is active.

Step 3: Update your Wunderkind tag URL to use the new subdomain

Once SST and the CNAME are configured, update the script URL that loads the Wunderkind tag for your SmartTag pixel and Conversion Pixel so it uses your first‑party subdomain instead of a third‑party domain.

Current tag examples

You may currently load Wunderkind from a URL such as:

• https://tag.bounceexchange.com/{websiteid}/i.js
• https://tag.wknd.ai/{websiteid}/i.js
• https://api.bounceexchange.com/...

Updated tag URL with SST

Update the script to:

• https://{your-sub-domain}/{websiteid}/i.js

Where:

• {your-sub-domain} is your new first‑party subdomain (e.g., wd.yourdomain.com).
• {websiteid} stays exactly the same as in your existing implementation.

Important guidelines:

• Do not use your primary domain (e.g., www.yourshop.com). Use a dedicated subdomain like wd.yourshop.com instead.
• Script placement and behavior remain unchanged — you’re only updating the domain portion of the URL.

Step 4: Validate and launch

Once DNS, SST, the Wunderkind tag URL, and your tag manager are updated:

1. Confirm SST is enabled

• Navigate to:
  https://tag.wknd.ai/<your-website-id>/i.js in your browser.
• Check that tag_state_domain_enabled is set to true.

2. Validate your SST domain

• Use dig/nslookup again on wd.yourdomain.com to ensure it returns the expected values (see Step 1).

3. Platform domain health checks

• Wunderkind periodically sends requests to https://<client-domain>/state/check-domain with the user‑agent wknd-bot to confirm your domain remains healthy for SST.

4. Verify in your browser (Chrome DevTools)
   After deployment, you can quickly confirm that your new SST domain is loading correctly using Chrome DevTools:

1. Open your site in Google Chrome (any page where the Wunderkind tag should fire).
2. Open DevTools:
   • Windows: Ctrl + Shift + I
   • Mac: Cmd + Option + I
   • Or via the Chrome menu: View → Developer → Developer Tools.
3. Go to the Network tab.
4. In the filter box, type your SST subdomain (for example, wd.yourdomain.com).
5. Refresh the page.
6. Confirm that you see a request to your SST subdomain for the Wunderkind script, for example:
   https://wd.yourdomain.com/{websiteid}/i.js
   • The Status column should show 200 (or another successful status) and Type should indicate a script.
7. (Optional) Click the request and review the Headers tab to confirm the Request URL uses your SST domain, and that it is not being blocked by the browser.

If you can see a successful request to your SST subdomain in the Network tab, your first-party domain is loading correctly from the browser’s perspective and SST is successfully wired through your site.

Shopify App: automatic deployment of your new domain

If you use the Wunderkind Shopify App for onsite tracking:

• The app already handles placement of the Wunderkind tag and pixels in your Shopify theme.
• Once your new SST domain is configured in Wunderkind AMP, Wunderkind can automatically deploy that domain via the app for onsite tracking.
• Installing and configuring the Shopify App does not trigger sends; it simply sets the technical foundation so your campaigns can run once you’re ready.

This means that for eligible Shopify stores, much of the onsite implementation is self‑service and low‑lift, while still following the same SST and first‑party principles described above.

FAQ: Privacy, cookies, and consent

Does SST change the data Wunderkind collects?
No. SST and first‑party domains change how reliably tracking works (especially on Safari/iOS), not the underlying data categories. Your existing campaigns and collection logic remain the same.

Does Wunderkind read all of our first‑party cookies?
No. Wunderkind only reads the first‑party cookies it sets and uses them strictly for session continuity and personalization. Other cookies on your domain remain governed by your own implementation and browser policies.

What if we want to further restrict cookie access?
You can configure stricter cookie attributes (for example, “Host Only” semantics via the Domain attribute) so that specific cookies are only visible on particular hosts and are not shared across subdomains. SST works correctly as long as Wunderkind can still access the Wunderkind cookies it sets.

How does this interact with our CMP and consent rules?
Your CMP still controls whether the Wunderkind tag is allowed to load and whether cookies are set. If a user does not consent, the tag should be blocked under your existing logic; SST does not circumvent your consent framework.

Will this break our existing onsite experiences or email/SMS flows?
No. SST and first‑party tracking are designed to be backwards‑compatible with existing Wunderkind campaigns. The primary change is improved visibility into iOS/Safari sessions, not a change in how experiences appear to users.