OPML generator: build a clean subscription list you can import once

OPML -- Outline Processor Markup Language -- is a lightweight XML format originally built for outliner software in the early 2000s, but its main use today is entirely different: it is the de facto standard for moving a list of podcast subscriptions between apps. The current version, OPML 2.0, is a short, stable specification maintained at opml.org, and it has barely changed in over a decade -- the Library of Congress's digital-format sustainability registry even lists it as a well-documented, low-risk format for long-term preservation. That stability is part of why so many unrelated podcast apps, feed readers, and directories all settled on OPML as a shared export and import format instead of inventing something proprietary.

The structure is intentionally minimal. An OPML document has a head (with metadata like a title and creation date) and a body containing outline elements. For a podcast list, each outline needs a type attribute of "rss", a text or title attribute holding the show's name, and -- the one attribute that actually matters for import -- an xmlUrl attribute pointing at the podcast's RSS feed address. An optional htmlUrl can point at the show's website. Outline elements can also nest inside one another, which is how apps that support folders or categories represent them: a parent outline groups child outlines representing individual shows underneath it, and an app that ignores nesting can simply flatten the tree and import every show anyway.

OPML matters most at the exact moments a listener has the least patience for manual work: an app is shutting down, a phone is being replaced, someone wants to try a different podcast player without losing years of accumulated subscriptions, or a listener wants to hand a curated list of shows to a friend instead of typing out titles one at a time. Exporting to OPML before an app disappears is the only reliable way to preserve a subscription list once its original source is gone. It is worth noting that two of the largest platforms, Apple Podcasts and Spotify, do not currently offer a built-in way to export or import OPML files -- which is exactly the gap a standalone OPML generator or third-party export tool is built to fill for listeners on those platforms.

Importing an OPML file is mechanically simple: a podcast app parses the document, walks through every outline element that has an xmlUrl, and adds each one as a new subscription using that feed address. What an OPML file preserves is limited to the subscription list itself -- show titles and feed URLs, and optionally site links. What it does not carry over is anything tied to listening history: playback position, which episodes have already been heard, downloaded audio files, custom playlists, or per-show settings like playback speed. Anyone switching apps should expect to rebuild those preferences manually in the new app, even after a clean OPML import restores every subscription and any folder structure the original list used.

The most common mistake is treating an OPML file as a full backup rather than a subscription list -- it will not restore played-episode history or downloads no matter how recently it was exported. The second is exporting a list that has accumulated years of dead weight: duplicate entries, shows that stopped publishing, or feed URLs that quietly changed when a podcast switched hosting providers, which breaks the xmlUrl link even though the show itself is still active elsewhere. It is worth pruning a list before exporting it, and spot-checking a few feed URLs afterward, rather than assuming every entry that was valid when you first subscribed is still valid today.