First-id

First-id operates as a B2B identity and data activation software provider. It creates persistent pseudonymous identifiers for consenting users, then makes those identifiers available through platform and API integrations so customers can perform recognition, audience activation and measurement across channels. Value is created by improving addressability and attribution in environments where third-party cookies and email-based identity are constrained, while fitting into existing SSP, DSP, CDP and analytics workflows.

First-id is a French identity infrastructure start-up that provides a privacy-first, deterministic identifier for consenting users across sites, devices and browsers. Its platform is designed to help publishers, advertisers, agencies and adtech platforms reconcile first-party data, activate audiences and support measurement, attribution and frequency management without relying on third-party cookies or email logins.

The company appears to monetise as a B2B software and API provider, integrating into existing adtech and martech stacks rather than operating as a media owner or agency. Its value proposition is based on GDPR-compliant pseudonymous identity, interoperability with programmatic and data platforms, and utility across web, in-app and CTV environments.