Can I use Metafields Guru to edit metafields created with another app?

Although Metafields Guru is the best and most popular tool for managing metafields, metafields are not an exclusive feature of ours. Metafields should be viewed as child objects that can be appended to a parent resource, such as a product or an order, to add more data on top of the standard properties. Metafields are securely stored in Shopify's database and manipulated via the API available to any other app with the respective access scope. 

The only exception is the app-owned metafields, which can be accessed exclusively by the app that created them.