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Updated: Jul 9, 2026

Using Custom link parameters

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Custom link parameters let you automatically append tracking information to the links in your posts. Each parameter you set up pairs a query parameter name with a merge tag, so every qualifying link goes out with subscriber-specific data attached, without you having to edit each link by hand.

This is commonly used to pass identifiers like a subscriber's hashed email or subscription ID to an external system, such as an ad platform, so that clicks can be matched back to the right subscriber.

Note: This is a different feature from Using UTM parameter tracking with beehiiv, which automatically tags links with utm_source, utm_medium, and utm_campaign values. Custom link parameters let you define your own parameter names and attach any supported merge tag to them, including subscriber-level data.

How Custom link parameters work

Once enabled, beehiiv scans the links in your post and appends your configured parameters to any link that qualifies (see the exclusions below). Each parameter is made up of two parts:

  1. Parameter name: the query string key that will be added to the URL, for example adt_ei or sid.
  2. Merge tag: the beehiiv merge tag whose value will be inserted for that parameter, for example {{subscriber_email_base64}} or {{api_subscription_id}}.

For example, a configuration pairing adt_ei with {{subscriber_email_base64}} and sid with {{api_subscription_id}} would turn a link like https://example.com/landing into something like https://example.com/landing?adt_ei=ZXhhbXBsZUBlbWFpbC5jb20&sid=48213.

If a link already has its own query parameters or merge tags, those are preserved. Your custom parameters are added alongside them rather than replacing anything already there.

Setting up Custom link parameters

  1. Go to Settings > General Info for your publication.
  2. Scroll down to the Custom link parameters section, and toggle on Automatic custom link parameters. 
  3. Once enabled, click on + Add parameter to add your first parameter.

  4. For each parameter you wish to add, add a Name and use the Value dropdown to select a value. Choose between beehiiv reserved fields and your own custom fields. 

  5. Repeat for each parameter you want appended to your links.
  6. Click on the Save changes button to finalize. 

Once saved, the parameters apply automatically to qualifying links across your posts. You don't need to edit individual links.

Merge tags commonly used with Custom link parameters

Any supported merge tag can be used, but these are the most common for tracking and matching subscribers on external platforms:

Merge tagWhat it passes
{{subscriber_email_base64}}The subscriber's email address, Base64-encoded.
{{subscriber_email_hash}}, {{subscriber_email_hash_sha1}}, {{subscriber_email_hash_sha256}}Hashed versions of the subscriber's email, useful for matching with ad platforms that require hashed identifiers.
{{api_subscription_id}}The subscriber's subscription ID, useful for API-based integrations.

For the full list of available merge tags, see Reserved beehiiv fields and merge tag examples.

Pro Tip: If you're passing subscriber data to an ad platform like Meta or Google Ads for match tracking, check that platform's documentation for which identifier format (Base64 or a specific hash) it expects before choosing a merge tag.

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