Universal ID 2.0 (UID2) is an open-source identity framework developed by The Trade Desk that replaces third-party cookies with a consent-based, email-derived identifier. For CTV — a medium that never had cookies — UID2 offers the potential to create consistent cross-publisher audience identity that device IDs alone cannot provide. In India, UID2 adoption is early-stage but growing, particularly among publishers who want programmatic identity infrastructure that aligns with DPDPA consent requirements.
What is UID2
UID2 is a deterministic identity solution built on hashed and encrypted email addresses. When a user authenticates with a publisher (by logging in with their email), the publisher generates a UID2 token from the user's email address using the UID2 infrastructure. This token — not the raw email — is passed into the bid stream. DSPs that support UID2 can match the token against their own UID2-enabled audience data.
The key properties of UID2:
- Consent-based: UID2 is only generated when the user has consented to their email being used for advertising. The consent is explicit and attached to the identifier.
- Deterministic: Unlike probabilistic device graphs, UID2 matching is exact — the same email generates the same identifier (within a rotation period), so audience matching is precise.
- Cross-publisher: Unlike device IDs (which are platform-specific), UID2 works across any publisher that implements it — a user authenticated on JioHotstar and Zee5 would generate the same UID2, enabling cross-publisher frequency capping and reach deduplication.
- Open framework: UID2 is governed by Prebid.org and is not proprietary to The Trade Desk, though The Trade Desk is the primary driver and primary DSP activation path.
How UID2 works technically
The UID2 process in a programmatic impression:
- User logs into a publisher app (e.g., Zee5) with their email address.
- The publisher passes the email to the UID2 operator service (which can be a private operator hosted by the publisher, or the public UID2 operator run by The Trade Desk).
- The operator generates an opaque UID2 token — an encrypted, time-limited representation of the user's hashed email.
- The publisher includes this UID2 token in the OpenRTB bid request (in the
user.idor UID2 extension fields). - DSPs that support UID2 decrypt the token and match it against their UID2-enabled first-party audience data or apply frequency caps across UID2-identified impressions.
- The UID2 token rotates periodically (typically every 24–30 hours) to limit long-term tracking, but the underlying email-to-UID2 mapping is consistent within that window.
Publishers can operate a private UID2 operator — keeping user emails entirely within their own infrastructure — or use the shared public operator. The private operator model is preferred by large publishers with data privacy concerns.
UID2 on CTV
For CTV specifically, UID2 addresses a gap that device IDs cannot fill: cross-publisher, cross-device identity for authenticated users. On CTV:
- Most premium India OTT apps require user authentication (login with email or phone). This means UID2 infrastructure can generate a consistent identifier for a large share of CTV viewing, unlike on web where most users are unauthenticated.
- UID2 enables cross-publisher frequency capping across different apps on the same device without relying on device IDs. A user watching on JioHotstar and then Zee5 on the same TV can be capped as one viewer if both publishers pass UID2 and the DSP supports it.
- UID2 also supports cross-device linking — if the same email is authenticated on a CTV app and a mobile app, the UID2 can link those sessions for cross-device measurement and frequency management.
Limitation: UID2 requires active support from both the publisher (to generate and pass tokens) and the DSP (to decrypt and match). Without bilateral adoption, it offers no value. This is the current bottleneck in India.
UID2 adoption status in India
As of mid-2026, UID2 adoption in India is growing but pre-scale:
| Category | Status | Notes |
|---|---|---|
| Publisher adoption (India CTV) | Early — handful of publishers testing | Zee5 and select mid-tier publishers have run UID2 pilots; JioHotstar has not publicly committed to UID2 (operates own identity infrastructure) |
| DSP support | The Trade Desk: full support; DV360: partial (Google has own identity framework) | TTD is the primary activation path for UID2 in India; DV360 users have limited UID2 benefit |
| Agency awareness | Growing — mainly TTD-centric teams at large holding companies | GroupM and Publicis programmatic teams with TTD relationships are most UID2-aware |
| DPDPA alignment | Positive — UID2's consent-at-collection model aligns with DPDPA's explicit consent requirement | UID2's consent documentation can serve as evidence of consent under DPDPA audits |
The single largest gap in India UID2 adoption is JioHotstar. Because JioHotstar represents 40–50% of India CTV streaming ad inventory, UID2 cannot reach cross-publisher scale without JioHotstar participation. JioHotstar currently operates its own identity infrastructure (tied to Jio/Hotstar login), which it has not connected to the UID2 framework.
UID2 vs alternative identity solutions for India CTV
| Solution | Basis | India CTV availability | Best for |
|---|---|---|---|
| UID2 (Universal ID 2.0) | Hashed email, consent-based | Early adoption, TTD primary | Cross-publisher identity for TTD buyers; DPDPA-aligned consent tracking |
| Device IDs (GAID, TIFA, AFAI) | Hardware/OS identifier | Widely available but platform-siloed | Within-platform frequency capping and retargeting |
| Household IP matching | IP address as household proxy | Available in all DSPs | Probabilistic household reach and cross-device bridging |
| Publisher first-party ID | Publisher's own subscriber ID | JioHotstar, Samsung Ads, etc. | Within-publisher targeting using publisher audience data |
| Data clean room matching | Hashed email/phone matched in secure environment | Growing — JioHotstar, Samsung | Advertiser first-party audience activation against publisher subscribers |
For most India CTV buyers in 2026, device IDs and publisher first-party IDs remain the primary targeting infrastructure. UID2 is worth monitoring and piloting for teams running TTD-centric programmatic operations — but it should not be treated as a current at-scale solution for India CTV cross-publisher identity.