Reading Values

A person’s realtime attribute values are served by the Membership API, with the same membership key and the same identity resolution as its is-member read. You can read them on their own, or in the same request as the person’s audiences.

Endpoint

GET /v1/attributes/{index}/{value}

Authenticate with a membership key (pk_) as a Bearer token, exactly as for the is-member read — see Authentication. The endpoint serves the same permissive CORS, so a browser can call it directly.

curl -H 'Authorization: Bearer <MEMBERSHIP_KEY>' \
  'https://membership.zeotap.com/v1/attributes/user_id/u_123?attribute=cart_value_30m,latest_category'

Response

A 200 OK returns each attribute’s current value under its key, in its own type:

{
  "attributes": {
    "cart_value_30m": 129.5,
    "add_to_cart_count_1h": 3,
    "latest_category": "running-shoes",
    "last_seen": "2026-10-09T08:14:03.512Z"
  }
}

Values only, and only values that exist. An attribute with nothing to report for this person — no matching event inside its lookback — is left out, not returned as null or 0. A count is the exception in practice: it is 0 rather than absent once the attribute is tracked, because zero events is an answer. Attributes that are Ready or Paused are not tracked and never appear.

So, as with the is-member read, branch on presence: a missing key means “no value for this person right now”, whatever the reason. An identifier Zeotap has never seen gets the same answer as a person with no matching events — counts of 0 and nothing else — because a membership key is published in a web page, and an invented identifier should learn nothing about the person it names.

The response carries no names, no result types and no notes about warm-up: those describe your workspace’s configuration rather than the person. The Lookup tab on an attribute’s page shows them for one person, as does Zeotap Agent when you ask it for someone’s values.

Every response is served Cache-Control: no-store.

Values and audiences in one request

Add ?include=attributes to the is-member read to get the person’s attribute values in the same response:

curl -H 'Authorization: Bearer <MEMBERSHIP_KEY>' \
  'https://membership.zeotap.com/v1/members/user_id/u_123?include=attributes'

{
  "memberships": [
    { "audience_id": "aud_cart_abandoners", "is_member": true }
  ],
  "attributes": {
    "cart_value_30m": 129.5
  }
}

The attributes block has the same shape as the attributes read: every tracked attribute with a value, values only. It is absent when no attribute has a value for this person. ?attribute= does not apply here; use the attributes read when you want only some keys.

Status codes

Freshness

A value is current as of the person’s last tracked event — usually within about a second of the event arriving — and covers its lookback counted back from the moment you read it, so a value can fall as old events leave the lookback without any new event arriving. Read at the moment you need the value rather than caching it.

A realtime attribute counts from when it was started, with no history from before. For its first lookback after starting — or after an edit that restarted it — a value covers less time than its lookback says. See Tracking starts from zero.

Next Steps

• Realtime Attributes — what a realtime attribute is and how to create one.
• Functions and Types — what each function returns.
• Membership API — the is-member read, keys and CORS.