Proxy with Caddy

Add the blocks

Add these inside your site's block in the Caddyfile, then reload Caddy:

# The script files.
handle_path /sp/js/* {
    rewrite * /cdn/sdk{path}
    reverse_proxy https://cdn.spreelytics.com {
        header_up Host cdn.spreelytics.com
        header_up -Cookie
    }
}

# Everything else: the tracking requests. Caddy adds X-Forwarded-For itself.
handle_path /sp/* {
    rewrite * /1.0{path}
    reverse_proxy https://sdk.spreelytics.com {
        header_up Host sdk.spreelytics.com
        header_up -Cookie
    }
}

Point the script at your proxy

In your Spreelytics snippet, load the script through /sp/js/ and add api_host:

<script src="/sp/js/spreelytics-loader.js"></script>
<script>
  Spreelytics.init({
    client_key: "YOUR_CLIENT_KEY",
    api_host: "https://www.example.com/sp",
  });
</script>

Check it works

Open your site with the browser's Network tab open and filtered by /sp/. The script files and requests like track/page should come from your own domain, with status 200. In Spreelytics, Settings → Tracking script says "Last seen just now" and Realtime shows you in your own country.

• Wrong country, or 200 and nothing arrives: the proxy isn't passing the visitor's IP address in X-Forwarded-For. See The visitor's IP address below.
• 401: the Origin and Referer headers didn't arrive, or your domain isn't in Allowed domains.