> ## Documentation Index
> Fetch the complete documentation index at: https://help.xitter.space/llms.txt
> Use this file to discover all available pages before exploring further.

# How federation works

> Share public accounts and posts between Xitter instances.

Xitter instances on a shared list see each other's public accounts and posts. People on one instance can follow, like, repost and reply to people on the others.

The list is [`instances.json`](https://github.com/Xittered/xitter/blob/main/instances.json) in the Xitter repository, and you join it with a pull request. [`INSTANCES.md`](https://github.com/Xittered/xitter/blob/main/INSTANCES.md) has the same list in a readable form.

Federation is on by default. Every instance picks up changes to the list within 5 minutes. The admin panel's Federation page shows when each instance last synced.

## What people see

A post from another instance names it after its time, for example `Xitter for Web - xit.example.org`.

Accounts from other instances wear a globe after their name. Clicking it opens a card about their instance: its name, whether it's on the list, how many of its accounts are here, and links to its rules, its source code and the setting that hides it.

Searching a full handle such as `@name@example.org` finds accounts on other instances.

## Hiding other instances

Anyone can hide accounts and organisations from all other instances, or only from instances they pick, in Settings > Other instances (`/account/instances`). Hidden accounts stay out of that person's timelines, replies, search and suggestions, except accounts they follow. The same page can also mute their notifications.

## Media from other instances

Pictures and videos from other instances aren't saved on your server. Your instance fetches them from their home instance when someone views them, and keeps the most recent ones in memory (64 MB by default, set with `FEDERATION_MEDIA_CACHE_MB`). They don't show while their home instance is down.

To keep copies on disk, set `FEDERATION_MEDIA=store`. To delete copies saved by an older version, run:

```bash theme={null}
bun scripts/drop-remote-media.ts
```

> **[Join the list](/federation/joining)**
>
> Requirements and the pull request.

> **[Moderating](/federation/moderating)**
>
> Defederating, suspensions and superadmins.


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