Understanding Mixpanel's Distinct ID Format for UUID

Aditya G. · 2025-04-18T13:42:37.771Z

Is Distinct ID $device: UUID is a correct value for mixpanel Distinct ID . Is this format set by mixpanel or just UUID is set by mixpanel

Understanding Mixpanel's Distinct ID Format for UUID | Mixpanel Community

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kapa.ai
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Hi Aditya G., Please stand by as I search the Mixpanel knowledge base for an AI-powered answer. I normally take about 15 seconds or so. In case AI cannot answer your question, feel free to reach out to Mixpanel support at mixpanel.com/get-support. If you have follow-up questions for this thread, please tag me again with your question: @kapa.ai <follow-up question> 👋
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kapa.ai
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The format $device:UUID is indeed a correct format for a Mixpanel Distinct ID, and this specific format is set by Mixpanel in certain scenarios.In Mixpanel's Simplified ID Merge system, when an event contains only a $device_id property (without a $user_id), Mixpanel automatically sets the distinct_id by prefixing the $device_id value with $device:. This is how Mixpanel differentiates between anonymous users (those identified only by a device) and known users (those with a user ID).For example, if you send an event with just a $device_id of "anonymous111": LBKS{ "event": "View Anonymous Page", "properties": { "token": "{{token}}", "$device_id": "anonymous111" } }LBKSMixpanel will automatically set the distinct_id to $device:anonymous111: LBKS{ "event": "View Anonymous Page", "properties": { "token": "{{token}}", "$device_id": "anonymous111", "distinct_id": "$device:anonymous111" } }LBKSThis prefixing is part of Mixpanel's identity management system and helps with ID clustering and user identity resolution across devices and sessions.For backward compatibility, if you manually set a distinct_id with the $device: prefix, Mixpanel will interpret it as a $device_id value.Mixpanel Documentation: Migrating to Simplified ID Merge explains this behavior in detail.
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