You can paste your OPML code or upload a file, and the tool will instantly render an interactive, collapsible list. We automatically detect links in your file and make them clickable, so you can easily explore the feeds or websites in your list.
Originally developed by UserLand Software as a native file format for the outliner application in its Radio UserLand product, it has since been adopted for other uses, the most common being to exchange lists of web feeds between web feed aggregators.
A file with the OPML file extension is an Outline Processor Markup Language file. It's saved in a particular structure using the XML format, and is used to exchange information between applications regardless of the operating system.