High Recall ID is a supplementary browser identifier optimized for coverage over precision. You can use High Recall ID when failing to recognize a returning visitor is more expensive than an incorrect match. It is best suited for user experience and analytics workflows — such as providing personalized experiences for anonymous users, improving returning user experience, increasing conversion, etc. For use cases where precision cannot be compromised — such as high-risk financial transactions — use the standard visitor ID instead. The standard visitor ID is optimized for precision — when there is ambiguity in browser signals between two visits, it prefers to create a new visitor ID rather than risk an incorrect match.Documentation Index
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High Recall ID does not match across different browsers. The High Recall ID for a Safari browser will be different from that for Firefox.
Benefits of High Recall ID
Improves conversion by recognizing more returning visitors
When a returning visitor isn’t recognized, their experience resets. Previously viewed products, applied filters, and personalization signals are lost — and they are treated as a first-time visitor. This increases drop-off and reduces conversion. Consider an e-commerce site where an anonymous user adds a pair of running shoes to their cart and leaves without purchasing. When they return the next day, the standard visitor ID, optimized for precision, may not recognize them if the browser signals vary between these two visits. As a result, their cart is empty, and the homepage shows no relevant recommendations. But High Recall ID can tolerate these small signal variations and recognize the user across sessions — their cart is preserved, and the homepage surfaces the products they previously viewed — reducing friction and improving the chance of conversion.Reduces friction for legitimate users
The standard visitor ID alone may not provide enough information to reliably distinguish legitimate users from suspicious ones. High Recall ID, used alongside the standard visitor ID, provides an additional layer of context to apply the appropriate level of friction to the right users. For example, detecting account sharing or account takeovers typically requires introducing friction — step-up authentication, re-verification, or access restrictions. When browser/device characteristics vary between sessions (e.g., a single user accessing from different locations or devices), the same friction can also be triggered for legitimate single users who aren’t sharing their account. Since High Recall ID stays stable across small browser/device variations, combining it with the standard visitor ID gives you a more reliable basis for introducing the right level of friction:- Apply little or no friction: When both the standard visitor ID and High Recall ID remain the same between sessions, the visit is likely legitimate.
- Apply moderate friction: When the High Recall ID remains the same, but only the standard visitor ID differs, there is some cause for suspicion.
- Apply high friction: When both the High Recall ID and the standard visitor ID are different between sessions, the browser is unfamiliar.
Availability
- Only for Enterprise Plans, upon request. If you would like to try High Recall ID, please reach out to our support team.
- Supported only for browsers.
- Supported by all of our Backend libraries.
High Recall ID in API responses
In API responses and webhooks, High Recall ID is represented by the JSON objectsupplementary_id_high_recall.
Feature comparison: Standard Visitor ID vs. High Recall ID
| Standard Visitor ID | High Recall ID | |
|---|---|---|
| Optimized for | Precision | Coverage |
| Confidence score | Yes | No |
| Supported for browsers | Yes | Yes |
| Supported for mobile devices | Yes | No |
| JavaScript agent response | visitor_id | Included in field sealed_result |
GET /events/{event_id} | identification object | supplementary_id_high_recall object |
| Webhooks | Yes | Yes |
| Supported in DELETE /visitors/ | Yes | No |
| Supported in CSV export | Exported in column identification.visitor_id | Exported in column supplementary_id_high_recall.visitor_id |
| Availability | All Plans, by default | Enterprise Plans only, upon request |