Systems and methods for automatically associating content characteristics to a third-party content are provided. A uniform resource locator identifying a resource is received from a content provider. The content is rendered to produce an object tree. A first node of the object tree is determined, where the first node represents a content slot. A second node of the object tree proximate to the first node is identified. The second node has a content characteristic, which is extracted. The extracted content characteristic is associated with the first node and stored.