How to Use a Mastodon Relay to Discover New Instances

When you join a new Mastodon instance, the local timeline shows only posts from users on that same server. This can feel isolating if the instance is small or specialized. A Mastodon relay connects multiple instances so they share public posts with each other, effectively expanding the local timeline. This article explains what a relay is, how to add one to your instance, and what to consider before enabling it.

What a Mastodon Relay Does and How It Works

A Mastodon relay is a special server that acts as a middleman between Mastodon instances. When an instance subscribes to a relay, it sends all public posts from its local timeline to the relay. The relay then forwards those posts to every other instance that has also subscribed. The result is that your local timeline fills with public posts from many different servers, not just your own.

Relays are not part of the default Mastodon software. They are run by third-party operators or by instance administrators who want to foster cross-instance discovery. Most relays are free and open for any instance to join, though some require approval from the relay operator. The relay does not store posts permanently. It only passes them through in real time.

For a relay to work, your instance must have the relay feature enabled in its Mastodon version. Mastodon 3.0 and later include built-in relay support. If your instance runs an older version, you cannot use relays until you upgrade. The relay itself must also be running a compatible relay software, such as the official Mastodon relay or the PubSubHubbub-based relay.

What a Relay Does Not Do

A relay does not give you access to private or unlisted posts. Only public posts are forwarded. It also does not let you follow users from other instances directly — you still need to search for the user and send a follow request. The relay simply populates the local and federated timelines with more content. It does not modify your instance’s rules or moderation policies.

Prerequisites for Using a Relay

Before you can add a relay, you need administrator access to your Mastodon instance. Only admins can add or remove relays. You also need the full relay subscription URL, which typically looks like https://relay.example.com/inbox. This URL is provided by the relay operator on their website or documentation. If you are not an admin, ask your instance administrator to consider adding a relay.

Steps to Add a Mastodon Relay to Your Instance

1. Find a relay subscription URL
   Search for public Mastodon relays using a web search engine. Common relays include “Relay List” maintained by the Mastodon community. Copy the full URL from the relay’s page. The URL must end with /inbox or similar endpoint.
2. Log in as an admin on your instance
   Use the account that has the admin role on your Mastodon server. If you are the instance owner, you already have admin rights. If not, contact your admin.
3. Navigate to Preferences > Administration > Relays
   In the left sidebar, click Preferences. Under the Administration heading, click Relays. This opens the relay management page.
4. Paste the relay URL into the form
   On the Relays page, you see a text field labeled “Relay URL.” Paste the full subscription URL you copied earlier. Click the “Add relay” button.
5. Approve the subscription request
   After you add the relay, Mastodon sends a subscription request to the relay server. The relay operator may need to approve the request manually. Some relays auto-approve. Check the relay’s status on the Relays page — it changes from “Pending” to “Enabled” once approved.
6. Verify the relay is working
   Wait a few minutes, then check your local timeline. You should see public posts from other instances that are also subscribed to the same relay. If you see no new posts, confirm that the relay URL is correct and that the relay is active.

Common Issues and Limitations When Using a Mastodon Relay

Local Timeline Flooded With Unwanted Content

If the relay forwards posts from many large instances, your local timeline may fill with posts that are not relevant to your community. To reduce noise, you can enable the “Manually approve followers” setting on your instance. This does not block relay posts directly, but it lets you moderate which remote accounts can interact with your local users. Alternatively, remove the relay and look for a smaller, topic-specific relay.

Posts Not Appearing After Adding a Relay

If posts from other instances do not appear, the relay may be offline or the subscription may still be pending. Check the Relay page in your admin panel. If the status shows “Pending” for more than an hour, the relay operator may not have approved your request. Try a different relay. Also verify that your instance’s firewall allows outbound connections to the relay’s domain.

Increased Server Load and Bandwidth Usage

A relay forwards a high volume of public posts, which increases the amount of data your instance receives. If your server has limited bandwidth or CPU, the relay may slow down your instance. Monitor your server’s resource usage after adding a relay. If performance drops, remove the relay or switch to a relay with fewer subscribers.

Mastodon Relay vs Default Federation

Item	Mastodon Relay	Default Federation
Content source	Public posts from all subscribed instances	Public posts from instances that your users follow
Setup required	Admin adds relay URL and waits for approval	No setup — federation happens automatically when users follow accounts
Control over content	Limited — you can only remove the relay	High — you block specific instances or users
Server load	High — receives posts from many instances	Moderate — receives only posts from followed accounts and their interactions

You can now add a Mastodon relay to your instance to discover public posts from other servers. Start by finding a relay that matches your instance’s topic or language. After adding the relay, monitor your local timeline and server performance for a few days. If you want more control over content, consider using the “Manually approve followers” setting to moderate incoming interactions. For advanced discovery, combine a relay with the federated timeline view to see posts from all connected instances.