What is first-party data in CTV advertising?

First-party data in CTV advertising refers to an advertiser's own customer or prospect data — CRM records, app user IDs, email addresses, mobile phone numbers, purchase histories — used to target CTV audiences. Unlike third-party data (purchased from data brokers) or DSP modelled audiences (inferred from browsing behaviour), first-party data is data the advertiser collected directly from its own customers with explicit consent. In CTV, first-party data is activated by uploading hashed customer identifiers to a DSP or publisher platform, which matches them against device IDs in its identity graph to create a targetable audience of CTV devices.

The practical process: (1) Extract the relevant customer segment from your CRM — e.g., lapsed users who last purchased more than 90 days ago. (2) Hash the identifiers (mobile numbers or email addresses) using SHA-256. Hashing protects the raw data during transmission. (3) Upload the hashed list to your DSP — DV360 (Customer Match), The Trade Desk (CRM Onboarding). (4) The DSP attempts to match each hashed identifier to a device ID in its graph. (5) The matched device IDs form your CTV first-party audience segment. (6) Target this segment in your CTV line items. In India, hashed mobile numbers produce the best match rates (20–35%) because mobile numbers are widely linked to Google and telecom identity graphs. Hashed emails match at 15–25% in India.

Three use cases that are only possible with first-party data: (1) Customer suppression — exclude your own existing customers from acquisition campaigns, preventing budget waste on people who have already converted. Even at 25% match rate, suppressing a quarter of your customer base from acquisition targeting is valuable. (2) Lapsed user re-engagement — serve CTV ads specifically to users who installed your app but have not opened it in 60+ days. CTV's premium brand environment is better suited to re-engagement than performance-only channels. (3) High-LTV upsell — target your most valuable customers with a premium offer on CTV. This audience is small, expensive to reach, but high-value. These three use cases outperform standard third-party audience targeting because the underlying data is real customer behaviour, not a modelled proxy.