Podcasting 2.0 and the Namespace That Apple Ignored

An open RSS extension adds chapters, transcripts, and streaming micropayments. The app that gatekeeps the industry hasn't touched most of it.

What the Namespace Actually Contains

In February 2021, Adam Curry and Dave Jones published the first stable draft of the Podcasting 2.0 namespace — a collection of new XML tags designed to extend the capabilities of a standard RSS feed without breaking anything that already existed. The project lives at podcastindex.org, a directory and specification hub that Curry and Jones built explicitly as an alternative to Apple's centralised catalogue.

The namespace prefixes its tags with podcast: and covers a range of features that RSS's original <enclosure> element never anticipated. The most widely adopted additions include <podcast:chapters>, which points to a JSON file containing timestamped chapter markers; <podcast:transcript>, linking to a full episode transcript in formats including plain text, HTML, SRT, and JSON; <podcast:soundbite>, marking a short clip suitable for promotion; and <podcast:funding>, a simple link to a support page. Each tag is additive: a feed carrying them validates as standard RSS and plays in any compliant app; the new tags are simply ignored by software that doesn't understand them.

The most technically ambitious element is <podcast:value>. It specifies a streaming payment channel — typically over the Lightning Network, Bitcoin's layer-two payment protocol — allowing a listening app to send tiny, continuous micropayments to a show's creator, by the minute or by the split. Recipients can be divided among hosts, editors, and guests by percentage, all declared in the feed itself. The Podcast Index calls this value-for-value, and it has no equivalent in any other podcast specification.

Apple's Directory, Apple's Rules

The structural tension is straightforward. Apple Podcasts has been the default point of submission and discovery for most podcast publishers since roughly 2005, when Apple bundled podcast support into iTunes. That position has made Apple's tag support the practical floor of the ecosystem: what Apple reads, publishers use; what Apple ignores, publishers file away as experimental.

Apple maintains its own proprietary namespace — itunes: — which covers categories, episode type, episode number, show artwork, and explicit ratings. These tags predate Podcasting 2.0 and are required for Apple directory listing. Apple has shown no sign of adopting Podcasting 2.0 tags. Its podcast subscription requirements make no reference to the namespace, and as of early 2025 none of the Podcast Index's core extensions appear in Apple's published feed guidelines.

Specifications are argued over in rooms like this one. Atom's took a working group two years; RSS 2.0's had a single author and a closing date.Photo: Kindel Media / Pexels

This creates a two-tier ecosystem. Publishers who want Apple directory presence must use itunes: tags. Publishers who want chapters, transcripts, or streaming payments for their actual listeners must layer Podcasting 2.0 tags on top of those, supported only by a subset of players. The burden is carried by the feed, not the directory.

Who Has Adopted It

Adoption among dedicated podcast applications is real and growing, even if it remains outside the mainstream. Fountain, Castamatic, Podverse, and Curiocaster support the value tag and streaming payments. Chapters are rendered natively in Podverse, Fountain, and the Podcast Addict app. Transcript display — arguably the most broadly useful feature for accessibility — is supported in Pocket Casts, Podverse, and several others.

Its podcast subscription requirements make no reference to the namespace, and as of early 2025 none of the Podcast Index's core extensions appear in Apple's published feed guidelines.

Spotify, which acquired Anchor in 2019 and has since absorbed a significant share of independent podcast hosting, has built its own transcript and chapter implementations outside the Podcast Index namespace. YouTube, which entered long-form audio in earnest around 2024, similarly runs its own infrastructure. Neither company has adopted Podcasting 2.0 tags.

The Podcast Index directory itself is open and crawlable, and a number of hosting platforms — including Buzzsprout and Captivate — generate Podcasting 2.0-compliant feeds by default, giving publishers the tags without requiring manual editing. That quiet embedding at the hosting layer is, in practice, the fastest route to namespace adoption: the publisher does nothing, and the feed leaves the platform already carrying chapters and transcript links.

The namespace is technically sound and practically useful. The obstacle is not the adoption curve — it is that the entity with the most leverage over the industry has the least incentive to add infrastructure it did not design.