Create a Lookalike Audience

Use Case

Find more people who research what your best audience researches
Grow an audience of people into a new intent audience with one call

A lookalike takes a seed audience of people. Delivr finds the intent topics where the seed concentrates, then creates an intents audience of high-intent people in those topics. The topics that define the seed are left out, so the new audience reaches people the seed does not already hold.

Prerequisites

Organization API key + secret pair (Authentication)
A project ID (Account Setup)
A seed audience of people in that project that has finished building. A company audience cannot be a seed.

Cost

An API key is billed one Predictive Signals unit per topic the new audience targets, and only when the audience is created. A call that creates nothing is free. The new audience is an ordinary intents audience, so downloading it bills as any other download does. See Rate Limits and Metering.

Steps

1. Try It in the API Explorer

Open Create a lookalike audience in the API Explorer. Use a test API key to try the call. A test key returns the topics and the audience that would be created. It sets created to false and the header X-Delivr-Mode: test. Nothing is written or billed.

To run the call:

Enter your key in X-Api-Key and your secret in X-Api-Secret.
Enter the seed audience's numeric id in id.
Enter your project ID in project_id.
Optional: enter a day and a name in the body.
Select Try It.

2. Create the Lookalike

curl -X POST "https://api.delivr.ai/api/v1/audiences/4769/lookalike?project_id=YOUR_PROJECT_ID" \
  -H "X-Api-Key: YOUR_API_KEY" \
  -H "X-Api-Secret: YOUR_API_SECRET" \
  -H "Idempotency-Key: lookalike-4769-2026-10-30" \
  -H "Content-Type: application/json" \
  -d '{"day": "20261028", "name": "People like Pricing page visitors"}'

The body is optional. day is the archived day to measure, as YYYYMMDD. It defaults to two days before today (UTC). name defaults to People like and the seed's name.

Send an Idempotency-Key. If your request times out, send the same call again with the same key. Delivr returns the same audience and does not create a second one.

3. Read the Answer

A new audience returns 201:

{
  "seed_audience_id": "4769",
  "day": "20261028",
  "supported": true,
  "created": true,
  "topics": [
    { "topic_id": "4eyes_119418", "lift": 6.2, "overlap": 140, "expected": 22.6, "p": 0.0001 }
  ],
  "audience": { "id": 8412, "status": "Pending", "audience_name": "People like Pricing page visitors" }
}

topics lists up to 10 topics, strongest lift first. These are the topics that are billed. audience has the same fields as the response of Create an Audience.

Some calls return 200 and create nothing. Check supported, preparing, and reason:

Answer	Meaning	What to do
`preparing: true`	Delivr is building the seed's membership index.	Call again later.
`supported: false` with a `reason`	No topic stands out on that day, the seed is a company audience, or lookalikes are not available.	Try another `day`, or a larger seed.

A 409 means the seed's membership index is older than day. Pick an earlier day, or retry after the next indexing run. A 404 means the seed does not exist in the project, or the day has no archived intent history.

4. Build and Download

The new audience starts in Pending. Poll it, preview it, and download it as in Create an Intent Audience, starting at step 3. Use GET /api/v1/audiences/{id}/dependents to see which audiences are built on a seed or on the new audience before you delete it.