# What are we talking about?
Mastodon and "the Fediverse" constitute a broad array of independent servers utilizing ActivityPub, which (perhaps to the surprise of some on Nostr) is *the* W3C standard for decentralized social networking. I'll be restricting most of my discussion here for Mastodon, which is most the "Twitter/Nostr"-like aspect of the Fediverse, and to my knowledge the only content bridged by Mostr and Momostr.
# Why Should We Care About Mastodon?
For one, Mastodon has something like ~500,000 active users. Most recent counts of Nostr DAU's average around ~15k. That's over an order of magnitude more interactions we could be having on Nostr. We spend so much time on Nostr lamenting why this or that X user doesn't come over to Nostr, yet there's the insanely obvious "growth hack" of bridging to Mastodon that gets little to no attention.
Bridging (if it actually worked) would allow for Mastodon users to keep what they like about Mastodon while still being able to interact with Nostr users, and vice versa. That's something that would be impossible on centralized systems like X or Facebook.
That would be great, right?
# Mostr and Momostr
Two years ago, which might as well have been 2 million years given the rapid evolution of Nostr, nostr:nprofile1qyt8wumn8ghj7un9d3shjtnyd968gmewwp6kytcpzemhxue69uhhyetvv9ujumt0wd68ytnsw43z7qghwaehxw309aex2mrp0yh8qunfd4skctnwv46z7qgmwaehxw309ankcetpwdhkuct5daezuer9wchhyetvv9usqgqyv87tanzvxd6y8xfj66u0zynfendhejtn44a9pt3k9kcntfr5m5vpa3kc created the "Mostr bridge." [Here he is at a Nostrasia conference in 2023](https://www.youtube.com/watch?v=075wrIJ1vHg), making an eloquent case for both the "why?" and "how?" of Mostr.
There's also another bridge called [Momostr.pink](https://momostr.pink/). It's operated by someone whose Github handle is Nanikamado, and apparently is a Nostr user but wishes to remain anonymous. Fair enough.
# Do These Bridges Actually... Work?
Now here's the problem. I will take you through my "new user journey" with Nostr earlier in 2025. Shortly after creating an npub and setting up a client, I started following hashtags to figure out who and what to follow. I saw that the vast majority of content from hashtags I followed was coming in from Mastodon, specifically either Mostr or Momostr.
Cool! Decentralized social media protocols talking to each other! How awesome! But shortly thereafter, the limitations became readily apparent.
# Mostr: Good for Discovery, Bad for Communication
The vast majority of Mastodon users that show up in hashtag searches are from the Mostr bridge (with NIP-05 names formatted as `username@server-com.mostr.pub`). However, what I quickly realized when I tried to reply to a Mostr-bridged user's posts is that, almost universally, the response doesn't go through. I know this because you can check the remote Mastodon instance, and nothing shows up. I tried the following test with three Mastodon users I follow to see if I could get a response:
Aaaaaand crickets.... Furthermore, if you go to the individual Mastodon servers where each of these posts originate, nothing shows up.
It seems pretty clear to me that at least one of the following is taking place:
1. Replies from Nostr users aren't being sent back through the Mostr bridge.
2. The remote Mastodon servers are rejecting the replies for some reason, and this error message isn't being propagated back to the Nostr user.
What exactly is going on, only nostr:nprofile1qyt8wumn8ghj7un9d3shjtnyd968gmewwp6kytcpzemhxue69uhhyetvv9ujumt0wd68ytnsw43z7qghwaehxw309aex2mrp0yh8qunfd4skctnwv46z7qgmwaehxw309ankcetpwdhkuct5daezuer9wchhyetvv9usqgqyv87tanzvxd6y8xfj66u0zynfendhejtn44a9pt3k9kcntfr5m5vpa3kc knows.
## What About Federation?
But wait! Could it just be that I've been trying to communicate with servers that don't federate with Mostr, as many have explicitly rejected it for "reasons"? No, all of the servers in the above example *do* claim to federate with Mostr.pub, as described in their `peers` API.
In fact, both Momostr and Mostr bridges seem to store notes from servers that *don't* federate with them; the purpose of which eludes me. Why present Nostr users with notes that seem like they can accept replies, when reality those replies will never be viewed by the original poster? But I digress...
## The One Exception
The "retro-tech" Mastodon instance [Retro Gaiden](https://retro-gaiden.com/about) is the only example of successful two-way communication I've had across the Mostr bridge. I have no idea what moderator nostr:nprofile1qyvhwumn8ghj7un9d3shjtnddakk7um5wgh8q6twdvhsqgxqexcr5rkwztv2lxhqachh5vxg6hh4eqcacar0nrxm934gpypzvqxy3xgs is doing to enable this, but whatever it is, 2-way communication with Mostr is actually possible on his server. I literally have never found another person who has replied back via Mostr.
# Momostr: The One That Works, But...
With the weird aforementioned exception of Retro Gaiden, all of the successful two-way communications that I've had with Mastodon have been through Momostr. The problem is, user discovery is a pain in the ass with Momostr.
My theory is that Mostr pre-caches vastly more Mastodon data than does Momostr. This is why, for given hashtag searches or your Nostr client's search bar, 99% of what shows up is from Mostr. That's great for *finding* the user, but not so great if you want to actually *interact* with them. For that, the best strategy I've found is
1. Discover users on Mostr, but
2. Follow them on Momostr.
This is a bit clunky, but here's how I've done it: Say I wanted to follow Meredith Whittaker's Mastodon account. I go to my client's search bar, and enter her name. Odds are, you're *only* going to see the Mostr account nostr:nprofile1qyt8wumn8ghj7un9d3shjtnyd968gmewwp6kytcqyzjzxljzpndskv3369clapumet3h5tdh40e0z23n0wt4xdmp3savyuv6gkp .
What I've found is that for most Mostr npub's there is also a corresponding Momostr npub you can follow. However, for whatever reason, the Momostr npub usually doesn't show up when searching for users in most clients. So here's what you have to do to take a Mastodon user you found on Mostr, and follow them on Momostr:
1. Take the username, in this example `Mer__edith@mastodon.world`
2. Format it for Momostr: `Mer__edith_at_mastodon.world`
3. Enter this into the NIP-05 `well-known` API of momostr.pink, so `momostr.pink/.well-known/nostr.json?name=Mer__edith_at_mastodon.world`
4. The API returns the public key, `62fde58e165c695686252e25dfc14fc650e4f9769224f3a02e35615d322e3420`
5. Now copy and paste this into your client's search bar, and the corresponding Momostr profile appears, nostr:nprofile1qyvhwumn8ghj7un9d3shjtnddakk7um5wgh8q6twdvhsqgrzlhjcu9jud9tgvffwyh0uzn7x2rj0ja5jyne6qt34v9wnyt35yqrdgady
My guess is that Momostr does a lot of profile and post fetching "on the fly", rather than pre-caching Mastodon posts and user data as Mostr seems to do. This is why Momostr profiles and events generally don't show up in searches. However, after you follow people on Momostr, I find that their posts appear naturally in my feed, "doubled up" with Mostr posts if I happened to follow the same profile there. So this is super-cludgy, but it seems to work.
# Conclusion: It's Tough to Cross the Bridge, But It's Worth It!
There's a magical feeling to being able to communicate across a completely different protocol, once I finally got it to work.
A user on X will *never* be able to communicate with a Facebook user. Same with, say, Instagram and TIkTok... Because these aren't protocols, they're companies, and the legal and fiduciary context in which they exist actively forbids them to interoperate.
But Nostr and Mastodon aren't companies, they're protocols. We can clearly interoperate, as Mostr and Momostr illustrate. So why aren't we?
Both Momostr and Momostr feel like a lot of Nostr projects; made with much fanfare and then abandoned, or at least maintained with a very light touch. I will credit Momostr's developer for at least (a) having a github repo and (b) being relatively responsive on it, but as I've shown here, much is unclear about how both of these relays operate.
Don't get me wrong; I like Nostr's weird, quirky and Bitcoin-heavy culture as much as the next pleb. But my interests span larger than Bitcoin and red meat, and the only other place in "decentralized social media" land where these conversations are happening is Mastodon.
[Images Source](https://www.slashfilm.com/1425470/indiana-jones-temple-of-doom-rope-bridge-danger/)