Creates or updates a user identity with custom properties and aliases.
User identities store custom properties about your users (email, name, plan, etc.) and allow you to track events by user ID.
Aliases let you reference the same user by multiple identifiers:
User identity creation is naturally idempotent. Calling identify multiple times for the same userId will update the properties without creating duplicates.
Properties are replaced on each identify call, not merged. Include all properties you want to keep.
API key authentication. Format: emitkit_xxxxxxxxxxxxxxxxxxxxx
Create API keys in your EmitKit dashboard. Keys are scoped to a specific organization and project.
Unique identifier for the user. This is your internal user ID. Must be consistent across identify calls for the same user.
1 - 255"user_123"
Custom properties about the user. Any valid JSON structure is accepted. Properties are replaced on each identify call, not merged. Common properties: email, name, plan, createdAt, etc.
{
"email": "[email protected]",
"name": "John Doe",
"plan": "pro",
"signupDate": "2025-01-15"
}Array of alternative identifiers for this user (emails, usernames, external IDs). Aliases allow you to reference users by multiple identifiers in your events. Duplicate aliases are silently ignored and returned in the response.
501 - 255[
"[email protected]",
"johndoe",
"[email protected]"
]