CMP (Consent Management Platform)

Definition

A CMP (Consent Management Platform) is a tool that displays the consent banner to website visitors, collects their choices (accept, decline, customize) and communicates those choices to tags and scripts to adapt their behavior. It is the essential technical component for GDPR compliance.

How it works

The CMP executes first on the page, before any other script. It blocks the execution of non-essential tags until the visitor has made their choice. Once consent is collected, it stores it (typically in a first-party cookie) and communicates the status to Google Tag Manager via Consent Mode or the TCF (Transparency and Consent Framework).

Leading CMPs

The most widely used CMPs include Cookiebot (Usercentrics), OneTrust, Axeptio, Didomi and Tarteaucitron. The choice depends on site size, budget, tracking tools in use and customization requirements. All must be certified as Google CMP Partners to work with Consent Mode v2.

Common mistakes

The most frequent errors are: a CMP that does not actually block tags before consent (GDPR violation), a Consent Mode misconfigured so it does not send the correct signals to GTM, or a banner design that biases the choice (dark patterns prohibited by the CNIL). A consent configuration audit detects these problems.