The announced end of third-party cookies is prompting many publishers to rethink their advertising strategy. Currently - even before the future evolution of Chrome - publishers are already losing up to half of their advertising revenues on the Safari and Firefox environments. First-id, is a unique opportunity to get more value out of publishers audiences, whereas the current model, based on third-party cookies, does not value content creators. From now on, publishers will be able to regain control of their inventory thanks to a cross-publisher 1st party cookie that works on all browsers (Chrome, Safari, Firefox, etc.) and all environments. The solution has been successfully tested for several months on the brands of the Prisma Media group and Cerise Media. The benefits observed are multiple: - Significant increase in revenue from cookie third less inventories thanks to better identification, - 100% of the audience is cross-site addressable in the publisher's DMP, both for advertising and for personalisation, - The publisher's campaigns with its own data can target all Internet users, even on Safari and Firefox. The ambition of first.id is to put publishers back at the centre of the digital ecosystem by helping advertisers and agencies to easily identify their customers on media brands and thus support the creation of quality content.