Link User API

Attaches a device to one of your users. Every event that device sent before the call — including in previous sessions — is retroactively attributed to that user, so nothing is lost.

POST /api/tracker/link-user/

bash

curl -X POST https://www.nohmo.in/api/tracker/link-user/ \
  -H "Content-Type: application/json" \
  -H "X-API-Key: pk_xxxx" \
  -d '{
    "deviceId": "a1b2c3d4...",
    "userId": "user_42",
    "email": "ada@example.com",
    "meta": { "plan": "pro" }
  }'

Field	Required	Description
deviceId	✓	The device to link. Must already exist — send an event or call /identify/ first
userId	✓	Your stable identifier for the user
email	—	Stored on the profile; used to merge the same user across devices
meta	—	Any JSON object of user properties (plan, role, signup date)

Response

json

{ "success": true, "data": { "ok": true } }

Note: Calling this again with the same userId from another device merges the two profiles, which is how one person using a phone and a laptop stays one user.

Status	Meaning
400	Invalid JSON, or deviceId / userId missing
401	API key missing or invalid
404	No device with that deviceId in this project