Uploading custom audiences: the CSV format, the statuses and the pitfalls

Custom audiences are the most direct lever in ChatGPT Ads: you bring your own customers and reach them — or people who resemble them — in conversations. The upload is quick, but a few details decide whether the list arrives cleanly. Here's the flow from file to ready-to-use audience.

The file

A CSV with a header row and the columns email and phone. Either column may be empty, but every row should have at least one value. Email addresses in lowercase, phone numbers in international format with country code. An export from Shopify, a CRM or a newsletter tool is enough — just remove columns that have nothing to do with identification.

The upload in Chatvertise

On the Audiences page you create a new audience with a name and pick the file. Chatvertise uploads it through the files API and passes along filename, type and size — the API requires this metadata together with the file, otherwise it rejects the request. The same applies later to adding, removing or replacing members: always a file in the same format.

The statuses after upload

• “Processing”: the list is being ingested and matched. Depending on size, that can take minutes to hours.
• “Ready”: the audience can be used in ad groups.
• Membership jobs: every add or remove runs as its own job. Chatvertise shows them in a table with status, and on failure the reason right next to it.

Three pitfalls

First: an audience that's still processing can't be archived — the API refuses until ingestion is done. Second: a second upload with “replace” overwrites the entire list, not just the differences; if you only want to top up new customers, use “add”. Third: the audience lives in the ad account, not in Chatvertise — if you remove the account from Chatvertise, it remains at OpenAI.

And then: lookalikes

Once the audience is ready, you can have a lookalike audience created from it — users who resemble your customers. To start, we recommend two ad groups: one with the customer list and a slightly higher bid, one with the lookalike. After a week you'll see which one has the better CPA.