External URL groups are objects that tell ETRNL the URLs that should be embedded into the tags. These typically represent products and point your tags to the page on your own website where the product information can be displayed. The URL groups allow you to program many tags that point to your product’s details page and collect useful analytics on these products.

Use cases

External URL Groups can only be created through our API because this process is intended to be automated. For example; every time you create a product within your website’s CMS, you could automate the creation of the corresponding URL group within ETRNL using the API.



Define the external URL


POST to the API

Define the URL

A custom URL can be defined by writing out your URL and wrapping 4 of the required parameters in curly braces ”{}“.

Custom URL Params

  • tagId - The ETRNL unique ID of the tag
  • enc - The encrypted message generated by the tag
  • cmac - he CMAC integrity data generated by the tag (Only required if tamper detection is not enabled)
  • tt - The encrypted tag tamper status generated by the tag. (Only required if tamper detection is enabled)
  • eCode - A KDF input parameter used for key decyrption



The custom URL params can only be used as a query parameter, or a URL slug.

Tag Tamper

For tag tamper URLs, you cannot include the cmac value as the tt message includes both the cmac and the encrypted tamper status.

So the custom URL would look something like:


POST to the API

Once you have your custom URL defined, you can POST to the /v1/url-groups endpoint to create the group in ETRNL.


  • appName - This is the name of the application used to create the URL Group (example: Salesforce Site)
  • name - The name of the product you want to authenticate
  • customUrl - The custom URL format
	appName: "Salesforce Site",
	name: "Invisible T-Shirt",
	customUrl: "https://example.com/?tagId={tagId}&enc={enc}&cmac={cmac}&eCode={eCode}"

Code examples to send the POST request can be found on the API page in multiple programming languages.

You will now see the URL group in the programmer with the app name as the prefix.