A start offset and an end offset can be identified within unfiltered content that is to be filtered. This unfiltered content can include HTML content. A corresponding start offset and an end offset of the unfiltered content can be matched against a set of content objects contained in a content cache. Each of the content objects can be associated with rule metadata. At least one filter rule can be extracted from metadata of a matching cache object. A programmatic action can be performed based upon the extracted filter rule. Computer readable output can result from the programmatic action. The output can include content that has been filtered in accordance with the extracted filter rule.