When choosing a Mastodon instance, the number of users or local posts alone does not tell you how well that server connects to the rest of the fediverse. Federation reach measures which remote servers your instance can communicate with and how many users it can actually discover. A server that blocks many popular instances or has a small moderation blocklist may feel isolated even if it has thousands of local accounts. This article explains how to compare Mastodon instances by their federation reach using built-in tools and third-party resources.
Key Takeaways: Comparing Federation Reach Across Instances
- Federation timeline: Shows all posts from remote servers the instance follows, revealing the actual reach of the server.
- Instance blocklist: Reviewing the list of suspended domains on an instance tells you which servers are excluded from its federation.
- Third-party tools like FediDB: Provides per-instance statistics on connected servers, user counts, and blocklist size.
What Federation Reach Means for a Mastodon Instance
Federation reach is the set of remote servers with which a Mastodon instance actively exchanges data. This includes posts, boosts, replies, and profile information. An instance with high federation reach sees content from many different communities, while a server with low reach sees mostly local posts and a narrow slice of the fediverse.
The reach depends on three factors: the instance’s moderation blocklist, the instance’s follow policies for remote users, and the decisions of other servers to block or limit the instance. If your instance blocks a large number of domains, those servers will not appear in your federated timeline. Conversely, if other instances block your instance, their users will not see your content.
A common misconception is that federation reach is the same as the total number of users on the fediverse. In reality, a small instance that follows many remote users may have broader reach than a large instance that blocks most other servers. Understanding reach helps you pick an instance where you can discover diverse perspectives and interact with users across the fediverse.
Steps to Compare Federation Reach Between Instances
You can evaluate federation reach using the instance’s built-in tools and external directories. Follow these steps to compare two or more instances.
- Open the Federated Timeline on the Instance
Log into the instance and click the Federated timeline tab, often labeled Federated or Global. This feed shows all posts from remote servers that the instance follows. Scroll through several pages to see how many different domains appear. A diverse set of domains indicates broad reach. - Check the Instance’s Blocked Domains List
Navigate to Preferences > Moderation > Domain Blocks. If you are not an admin, use the instance’s public about page at https://[instance]/about/more. Look for a section listing suspended or limited domains. Count the number of entries. A long blocklist reduces reach. - Use FediDB to Compare Instance Statistics
Go to FediDB.org and search for the instance name. On the instance page, look for the Connected Servers count. This number shows how many distinct domains the instance has seen posts from in the last 30 days. Compare this count across instances. - Review the Instance’s Federation Graph
Some instances expose a federation graph at /about/federation. This page lists recent interactions with remote servers. Look for servers from different regions and language groups. A graph with only a few clusters suggests low reach. - Search for the Instance on Instance Blocklists
Use tools like The Blocklist or oliphant.social to see if the instance appears on other servers’ blocklists. If many popular instances block the target instance, its reach will be limited even if it does not block many servers itself.
Common Issues When Evaluating Federation Reach
Federated Timeline Appears Empty or Sparse
If the Federated timeline shows very few posts or only posts from a handful of servers, the instance likely has low federation reach. This can happen because the instance blocks many domains, or because it is new and has not yet discovered many remote servers. To improve reach on a new instance, follow users from diverse instances. Their posts will pull content from their home servers into your instance’s federated timeline.
Blocklist Is Not Publicly Visible
Some instances hide their blocklist from non-admin users. If you cannot view the blocklist on the about page, search for the instance name along with the phrase “blocklist” or “suspended domains” in a search engine. Community-maintained lists often report which servers an instance blocks. Alternatively, ask the instance admin directly.
Connected Servers Count on FediDB Differs From Actual Reach
FediDB counts servers that have interacted with the instance in the last 30 days. This metric can be misleading if the instance has many connected servers but most of them are inactive or low-traffic. Cross-check the count by looking at the diversity of domains in the Federated timeline. A high count with many inactive servers still indicates some reach, but not necessarily active engagement.
Mastodon Instance Federation Reach: Built-In Tools vs Third-Party Tools
| Item | Built-In Tools | Third-Party Tools |
|---|---|---|
| Data source | Instance’s own database and logs | Public APIs and crawled data from multiple instances |
| Federated timeline | Shows live posts from all known remote servers | Not available; third-party tools show aggregated statistics |
| Blocklist visibility | Shows only the instance’s own blocklist | Shows cross-instance blocklist data, including which servers block the target instance |
| Historical data | Limited to current state | Often includes historical connected server counts and trends |
| Ease of comparison | Requires logging into each instance separately | Allows side-by-side comparison of multiple instances on one page |
You can now evaluate federation reach by combining the Federated timeline, blocklist review, and FediDB statistics. Start by checking the Federated timeline on any instance you are considering. If the timeline shows posts from many different domains, the instance likely has good reach. Complement this with a FediDB search to see the connected servers count and any blocklist reports from other tools. This two-step approach gives you a reliable picture of how well an instance connects to the wider fediverse. For a deeper comparison, join a few active instances temporarily and observe the diversity of content in the Federated timeline over a week.