This article describes what OPML files are, how to open them, and how to convert them to another format such as XML, HTML, CSV, etc.

A file with the OPML file extension is an Outline Processor Markup Language file. It is saved in a particular structure using the XML format and is used to exchange information between applications regardless of the operating system.

This file format is often used as an import/export format for RSS feed reader programs. Because an OPML file can contain a collection of RSS subscription information, it is an ideal format for backing up or sharing RSS feeds.

Virtually any program that manages RSS feeds should be able to import and export OPML files. Feedly is one example that can import one (log in and open the OPML Import page). The Thunderbird email client should also work.