NosillaCast Apple Podcast account in Mastodon using Mona

Subscribe to Podcasts … Through Activity Pub … Using Podcast Index … on Mastodon

By now you’ve probably figured out how to follow podcasts in your podcatcher of choice. I’ve just learned of another option that I’m not sure is easy or will be a widespread method, but it’s definitely interesting.

You’ve at least heard of Mastodon by now, even if you’re not an avid user like I am. Mastodon is a decentralized social networking platform, which means no one is in charge, and there’s no algorithm running in the background suggesting you follow Nazis. Quite refreshing.

While Mastodon is a platform, that platform runs on a decentralized social networking protocol called Activity Pub. Mastodon is just one of the more than 40 different platforms now based on the Activity Pub protocol. Probably the most well-known platform using Activity Pub is Threads from Meta.

Another term to understand is the Fediverse. Because so many platforms use Activity Pub, it’s possible for the platforms to intercommunicate and this collection of social networking platforms is called the Fediverse. Imagine writing a post on Threads, and it shows up on Mastodon to your followers there. Threads is just starting to open up in this way, but you can already do things like cross-post to services like from Mastodon and vice versa.

Ok, we have the Fediverse, which is a collection of social network servers, and we have platforms that talk to each other over the Activity Pub protocol, and one of those platforms is Mastodon.

But what the heck does all this have to do with podcasting? A gentleman named Evan Prodromou (@[email protected]) wrote a post on Mastodon explaining how you can subscribe to podcasts through Mastodon. It’s all thanks to Activity Pub being the underlying open source protocol, and podcasting depending on open source RSS.

I’ll walk through this slowly and then give you the short version of how to do it again at the end.

Podcast Index

It starts with a service called Podcast Index at The Podcast Index is an open database of over 4.2M podcasts, running on an open source API. If you search for a podcast, say maybe the NosillaCast for example, you will be shown a page dedicated to the NosillaCast.

Podcast Index showing multiple episodes of the NosillaCast.
Podcast Index for the NosillaCast

It’s a beautiful layout with the album artwork and the tagline for the show. You can scroll through the episodes with the most recent at the top, and each has a nice player. This is already a terrific site to know about, even if you don’t think subscribing to podcasts inside Mastodon is cool. The Podcast Index is funded by donations so if you end up using it maybe throw them some coins.

Now let’s talk about using the Podcast Index with Activity Pub to subscribe inside Mastodon. Here’s where it gets a smidge nerdy. After searching for a podcast in the index, look at the URL for the show. All of the shows start with the same URL:


But they each have a unique number at the end of that URL. The NosillaCast’s unique number is 851643.

Podcast index url for NosillaCast ending in 851643.
NosillaCast’s Unique URL in the Podcast Index

We’re going to need that unique number in order to follow the podcast on Mastodon.

All people/accounts you follow on Mastodon have a username and a server where they’re located. For example, to follow me, you look for @[email protected].

Because of the integration of the Podcast Index into Mastodon, you can follow a podcast in the same way. But instead of a username like @podfeet, you follow that unique number on the server So the account to follow for the NosillaCast would be @[email protected].

To follow an account, you have to search for it, so just plop that @[email protected] into the search field. When search finds the account, it will look like any normal Mastodon account with the album artwork for the podcast, a link to, and the RSS feed URL.

NosillaCast Apple Podcast account in Mastodon using Mona.
NosillaCast Apple Podcast Account on Mastodon

It will show one post, and one post only, which is to the most recent episode of the show. The body of the episode post will start with the words, “New Episode:” followed by the title of the episode. That title is a link to the episode on the Podcast Index website for the NosillaCast.

My first thought was that I wish the link took people to my website for the episode, but as I thought about it, the Podcast Index gives the user a delightful experience. The episode they clicked on is ready to play, and they can see older episodes and play them directly there too. There’s also a swell little globe icon indicating where to click to jump to my blog post for the episode so you can see the full show notes. Heck, they even give you a link to open a download link to where my audio files are stored so you can have the podcast episode for posterity. They even make it easy to share links with others. I couldn’t find any reason not to love this interface.

I was curious whether all podcasts look and act the same, so I looked for Bodie Grimm’s Kilowatt Podcast and easily found the unique number for the show: 52300. When I searched for and then followed Kilowatt on Mastodon using the Podcast Index number, (@[email protected]), I could see the podcast, but I didn’t immediately see a post for the latest episode.

I’m not exactly sure what causes the latest episode to show up on Mastodon, but later when I went back I could see the most recent episode. It’s not that he posted a new episode and that made it show up, it was an episode that aired before I subscribed on Mastodon.

It’s almost as though the Podcast Index is recreating this account for each person who asks for it because I had Steve subscribe to the NosillaCast on Mastodon and it didn’t show a new episode right away, and it says “0 following”.

If my observations are leading to the correct conclusion, then it makes sense that the newly created account on Mastodon hasn’t had time to pull any content yet, and only does after some short bit of time.

The Easy Method

As usual, I’ve made this long and detailed, which I hope is valuable to understanding how this stuff works. It can make things sound harder than they are though, so let’s go through the 3 easy steps to subscribing to a podcast in Mastodon as I learned from Evan Proromou:

  1. Look up a podcast at
  2. Find the unique number at the end of the URL in your browser. NosillaCast example: https:// → 851643
  3. Follow @[email protected]. For example, @[email protected].
  4. Get podcast updates over ActivityPub!

Bottom Line

I think this is a cool example of the power of the Fediverse and of Activity Pub and of open source. It may be too nerdy of a solution for you, but at the very least you learned about the Podcast Index where you can go to find your favorite podcasts and listen in a beautiful web interface with links to the original source.

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