What is it? The OpenLink Structured Data Sniffer (OSDS) is an extension for Web Extensions compliant browsers (e.g., Google Chrome, Microsoft Edge, Opera, and many others) that discovers Metadata embedded within HTML documents as Structured Data Islands and presents what's discovered using a Property Sheet presentation style. Currently, OSDS supports discovery and processing of Structured Data Islands published using notations such as Microdata, RDFa, JSON-LD, RDF-Turtle, RDF-XML, CSV, and JSON. Why is it important? It simplifies the process of understanding what a given HTML document is about, via its metadata, for both end-users and developers. For instance, it helps Digital Brand Managers, Digital Content Managers, and Semantic Search Engine Optimization (SSEO) practitioners understand what may or may not be affecting Search Engine Results Pages (SERPs) placements. How is it used? Simply install the extension to your browser and then visit a page of interest. On page arrival, the OSDS icon will be visually activated thereby indicating metadata discovery; once the icon is clicked, you will be presented with a presentation of transformed metadata.