MercadoLibre

Overview

MercadoLibre is the largest e-commerce marketplace and fintech platform in Latin America, operating across 18 countries with particular dominance in Brazil, Mexico, Argentina, and Colombia. Its advertising division, MercadoAds, enables brands selling on the marketplace to run performance campaigns and deploy conversion tracking pixels on their own websites. The platform also operates MercadoPago (payments) and MercadoCredito (lending), meaning scripts from the MercadoLibre ecosystem may appear on third-party merchant sites in multiple contexts.

What This Script Does

MercadoAds pixel loads JavaScript from http2.mlstatic.com or tracking.mercadolibre.com. The pixel fires on advertiser and merchant websites to track user interactions that can be attributed to MercadoLibre ad campaigns. Tracked events include product detail page views (with product ID, category, and price), add-to-cart actions, checkout initiations, and completed purchases (with order value and product list).

Cookies and identifiers: The pixel sets a _ml_uid cookie (typically 90-day expiry, third-party on non-MercadoLibre domains) that contains an obfuscated visitor identifier. A ml_attribution cookie (30-day expiry) stores the click ID from the last MercadoLibre ad click that brought the visitor to the site. These identifiers are used to match on-site conversions back to ad impressions within MercadoAds' attribution windows.

Retargeting audience construction: Visitor behavior recorded by the pixel (product views, cart additions, purchase completions) is used to build Custom Audiences within MercadoAds. These audiences enable advertisers to show targeted ads to past site visitors browsing the MercadoLibre marketplace. The pixel also supports lookalike audience creation from conversion data.

Data transmitted: Each event payload sent to MercadoLibre's tracking servers includes the page URL, referrer, the event type, event-specific properties (product IDs, transaction values), the visitor's _ml_uid identifier, IP address, and user agent. On the MercadoPago integration variant, transaction-level data including amounts may also be included for payment attribution.

Consent & Compliance

The MercadoLibre advertising pixel is firmly in the marketing consent category. It tracks user behavior on third-party websites for the dual purposes of conversion attribution (measuring the effectiveness of ad spend on MercadoLibre) and retargeting audience construction (enabling future ad targeting of past visitors). Both purposes are non-essential advertising activities.

Under GDPR and the ePrivacy Directive, the _ml_uid and ml_attribution cookies are non-essential tracking cookies that require explicit prior consent before being set. The behavioral profiling for retargeting audiences constitutes automated processing of personal data under GDPR Article 22 context. IAB TCF purposes that apply include Purpose 1 (Store and/or access information on a device), Purpose 3 (Create a personalised ads profile), Purpose 4 (Select personalised ads), and Purpose 7 (Measure ad performance).

Brazil's LGPD (Lei Geral de Proteção de Dados) is particularly relevant given MercadoLibre's scale in Brazil. LGPD requires a lawful legal basis — typically consent (consentimento) for marketing tracking — and mandates data subject rights including access, correction, and deletion. MercadoLibre's operations also fall under Argentina's PDPA and Mexico's LFPDPPP.

Under CCPA/CPRA, sharing visitor behavioral data with MercadoLibre for ad targeting constitutes a sale or share of personal information, requiring a "Do Not Sell or Share My Personal Information" opt-out mechanism for California residents.

Should You Block This Without Consent?

Yes. The MercadoLibre advertising pixel tracks conversions and builds retargeting audiences — both are non-essential marketing activities. The pixel sets persistent tracking cookies and transmits visitor behavioral data to a third-party advertising platform. Block until the visitor explicitly consents to marketing cookies and advertising tracking.