
Harness the power of your
first-party data
What is First-id?
First-id enables you to identify all your consented users across every website, device, and browser, and recognize them within partner networks as well as offline. It delivers up to 60% more reach, while remaining fully GDPR-compliant, omnichannel, and independent with no login required and no encryption needed for sharing.


The cornerstone of your identification strategy
- Persistent, anonymous, and deterministic identification
- Omnichannel reach
- Controlled exposure frequency
- Deduplicated measurement
Advertisers
- Unify and enrich my 1st party data
- To identify, qualify and precisely personalize my interactions with users
- No email
Publishers / Media
- Unify and enrich my 1st party data
- To increase the volume and value of my audiences tenfold
- No email or third-party cookies
Agencies
- Optimize targeting and audience planning
- To increase the reach and impact of my media campaigns
- No third-party cookies
Adtech
- Maximize the interoperability of my tools
- For more precise, personalized and efficient service
- In compliance with RGPD

Whether you are a
media, e-retailer or advertiser
First-id helps you meet your challenges:
Data
- Identify
- Reconciling
- Qualify
- Exchange
Activation
- Target (Re-targeting)
- Address (Reach)
- Mastering repetition (capping frequency)
- Measuring performance
How does First-id help you respond to these challenges?
Deterministic
Precise, persistent identifiers based on a combination of strong signals
Powerful
Cross-domain, cross-device, cross-browser compatible
Interoperable
For use in all your marketing and advertising tools
Partner Sovereignty
The partner controls the creation and transfer of its first-party cookie
GDPR Compliance
User consent, opt-out management and anonymous ID
- Read more
+ 250 partner media sites and advertisers
Latest News
Live Data enhances its “Data & Intentions” offering through the integration of First-id
Live Data enhances its "Data & Intentions" offering through the integration of First-id to provide greater reach, continuity, and performance…

CTV & digital: finally measuring the real impact of campaigns
How can you tell if your CTV campaigns are actually generating visits, conversions… or business?Even today, most players can't answer…

Mediarithmics natively integrates First-id
The European Customer Data Platform (CDP) Mediarithmics has announced the native integration of First-id into its technology stack. The European Customer Data Platform (CDP) Mediarithmics has…

First-id, Klox and Rock en Seine: +52% ROAS Thanks to Our Meta CAPI Solution
Paris, September 23, 2025 – First-id is proud to announce a strategic partnership with Klox, the entertainment-focused media agency, and…















































