DIA Argentina — OneApp AR / ClubDia: Unifying 3 User Bases

3 user bases unified into a single identity, with no re-registration required

The real challenge: DIA Argentina had the same user scattered across up to 3 separate, disconnected bases — the website/e-commerce, the current app, and the physical Club DIA card (its discount program). The engineering team asked for these bases to be unified into a single identity. My role: design a login that asked for email + DNI together — that pair is what recognizes the user —, matched duplicate records across the 3 bases (including duplicate emails) and issued a new, unique discount code, valid both in the app and when given at the store checkout.

The problem wasn't the login itself — it was that the same person could exist in 3 places at once (bought on the website, has the app installed, carries the physical Club DIA card), each base with its own identifier and no link between them. Engineering needed to migrate and unify that data; design's job was to make sure users never felt that complexity — they'd just enter the email and DNI they already had, with no re-registration.

OneApp AR (ClubDia) brought together 3 systems, each with its own user base: e-commerce, the app and the physical Club DIA program. Unifying them was a direct request from engineering — the product challenge was creating a login flow that, from email + DNI, recognized the user and resolved duplicates across the 3 bases without friction or requiring a new sign-up.

3 fragmented user bases became a single identity per person, with a login that recognizes the user by email + DNI — no new sign-up required — and a single discount code valid in the app and at the store checkout. It delivered on engineering's request without adding any noticeable friction for end users.