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Change in Anonymous User ID System at kapa.ai: From anonymous to $device | Mixpanel Community

Change in Anonymous User ID System at kapa.ai: From anonymous to $device

·Aug 08, 2025 10:38 AM·

kapa.ai In the beginning our anonymous users had a distinct id that included "anonymous", but now they have a distinct id with $device - Why is that?

2 comments

· Sorted by Oldest

kapa.ai
APP
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Please stand by Moritz H. as I search the knowledge base. I normally take about 15 seconds or so. 👋
Feel free to ask a follow-up question once I've answered by mentioning me with @kapa.ai
kapa.ai
APP
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The change you’re seeing—from anonymous users having a distinct_id like "anonymous..." to one prefixed with "$device:" (e.g., "$device:anonymous111")—is due to how Mixpanel’s Simplified ID Merge API handles anonymous user identification.With the Simplified ID Merge API, Mixpanel uses the $device_id property to track anonymous users. When an event is sent with only a $device_id (and no $user_id), Mixpanel automatically sets the distinct_id to "$device:{device_id}". This is a deliberate design to clearly distinguish anonymous device-based IDs from identified user IDs. For example: LBKS{ "event": "View Anonymous Page", "properties": { "token": "{{token}}", "$device_id": "anonymous111" } } // Mixpanel sets: "distinct_id": "$device:anonymous111"LBKSIf you previously used a different ID convention (like just "anonymous...") for anonymous users, the switch to the "$device:" prefix likely coincided with a migration to the Simplified ID Merge API or an update in your implementation to follow Mixpanel’s current best practices. This prefixing helps Mixpanel distinguish between device-based (anonymous) and user-based (identified) IDs, ensuring more accurate identity management and merging behavior Understanding Simplified ID Merge.In summary: Anonymous users now have a distinct_id prefixed with "$device:" because Mixpanel’s Simplified ID Merge API automatically applies this format to all anonymous device IDs for clarity and consistency Identifying Users (Simplified).
kapa.ai is still learning and improving, please let me know how I did by reacting below.
ℹ️ Tip: Mention @kapa.ai in the thread for follow-ups or DM the app for 1-to-1 help.