master_device_id Cookie

What does the master_device_id cookie do?

Used to track users across multiple devices for merchant login purposes. This cookie is set when a user logs into their account on a device and is used to authenticate subsequent logins from that same device.

Why this cookie matters

This cookie is commonly used by shopify for preferences purposes – such as tracking usage behaviour, optimising experience, or enabling marketing functionality.

Because it's categorised as preferences, many jurisdictions require that users give explicit consent before it can be activated. If blocked or denied by the visitor, preference-related features (like remembering language or layout choices) may not function properly.

How Cookifi helps you manage this cookie

Cookifi automatically detects cookies like master_device_id, categorises them, and gives you full control over when and how they load - based on your users' consent choices.

Whether you manage consent via Google Tag Manager, consent APIs (like the Shopify or WordPress Consent API), or prefer automatic cookie blocking or manual script control, Cookifi integrates seamlessly into your stack.

Built for technical marketers, business owners and developers, Cookifi offers flexibility without sacrificing compliance.