NodeInfo

NodeInfo is a protocol for exposing metadata about a server. It provides information like software name, version, usage statistics, and supported protocols.

Specification

• Repository: https://nodeinfo.diaspora.software/
• Schema: https://nodeinfo.diaspora.software/schema.html (JSON Schemas in jhass/nodeinfo)
• Fediverse guidance: FEP-0151 (FINAL)

How It Works

1. Client fetches /.well-known/nodeinfo
2. Response contains links to NodeInfo documents
3. Client fetches the NodeInfo document
4. Gets server metadata

Discovery

Request

GET /.well-known/nodeinfo HTTP/1.1
Host: example.com
Accept: application/json

Response

{
  "links": [
    {
      "rel": "http://nodeinfo.diaspora.software/ns/schema/2.1",
      "href": "https://example.com/nodeinfo/2.1"
    },
    {
      "rel": "http://nodeinfo.diaspora.software/ns/schema/2.0",
      "href": "https://example.com/nodeinfo/2.0"
    }
  ]
}

NodeInfo Document

Schema 2.1 (Current)

All of version, software (with name and version), protocols (at least one), services, openRegistrations, usage (with users) and metadata are required by both the 2.0 and 2.1 schemas; software.name must match ^[a-z0-9-]+$.

{
  "version": "2.1",
  "software": {
    "name": "myserver",
    "version": "1.0.0",
    "repository": "https://github.com/example/myserver",
    "homepage": "https://example.com/"
  },
  "protocols": ["activitypub"],
  "usage": {
    "users": {
      "total": 1000,
      "activeMonth": 500,
      "activeHalfyear": 800
    },
    "localPosts": 50000
  },
  "openRegistrations": true,
  "services": {
    "inbound": [],
    "outbound": ["atom1.0", "rss2.0"]
  },
  "metadata": {
    "nodeName": "Example Server",
    "nodeDescription": "A friendly ActivityPub server"
  }
}

Mastodon (4.7) publishes only NodeInfo 2.0: mastodon.social's /.well-known/nodeinfo links just /nodeinfo/2.0, with nodeName, nodeDescription, optInServerDirectory and optInServerRecommendation in metadata. Don't assume a 2.1 document exists — follow whatever the discovery document links.

Properties

Property	Description
version	NodeInfo schema version
software.name	Software name (^[a-z0-9-]+$)
software.version	Software version
protocols	Supported protocols
usage.users	User statistics
usage.localPosts	Number of local posts
usage.localComments	Number of local comments (optional)
openRegistrations	Whether signups are open
services	Third-party services the server can receive from (inbound) or publish to (outbound), e.g. rss2.0
metadata	Additional custom data

Implementation

Discovery Endpoint

// Use your configured domain, not req.hostname (the Host header is client-controlled)
const DOMAIN = 'example.com';

app.get('/.well-known/nodeinfo', (req, res) => {
  res.json({
    links: [
      {
        rel: 'http://nodeinfo.diaspora.software/ns/schema/2.1',
        href: `https://${DOMAIN}/nodeinfo/2.1`
      }
    ]
  });
});

NodeInfo Endpoint

app.get('/nodeinfo/2.1', async (req, res) => {
  const stats = await getStats();

  // The protocol asks for this media type, with the schema as profile
  res.type('application/json; profile="http://nodeinfo.diaspora.software/ns/schema/2.1#"');
  res.send(JSON.stringify({
    version: '2.1',
    software: {
      name: 'myserver',
      version: '1.0.0',
      repository: 'https://github.com/example/myserver',
      homepage: 'https://example.com'
    },
    protocols: ['activitypub'],
    usage: {
      users: {
        total: stats.totalUsers,
        activeMonth: stats.activeMonth,
        activeHalfyear: stats.activeHalfYear
      },
      localPosts: stats.localPosts
    },
    openRegistrations: true,
    services: {
      inbound: [],
      outbound: []
    },
    metadata: {
      nodeName: 'My ActivityPub Server',
      nodeDescription: 'A custom ActivityPub implementation'
    }
  }));
});

async function getStats() {
  const now = new Date();
  const monthAgo = new Date(now - 30 * 24 * 60 * 60 * 1000);
  const halfYearAgo = new Date(now - 180 * 24 * 60 * 60 * 1000);

  return {
    totalUsers: await db.users.count(),
    activeMonth: await db.users.count({ lastActiveAt: { $gte: monthAgo } }),
    activeHalfYear: await db.users.count({ lastActiveAt: { $gte: halfYearAgo } }),
    localPosts: await db.posts.count()
  };
}

Schema Versions

2.0 vs 2.1

Version 2.1 adds:

• software.repository - Source code URL
• software.homepage - Project homepage

FEP-0151 says servers SHOULD implement 2.1. Clients follow the highest version linked from the discovery document, so publishing only 2.1 is fine; publish 2.0 too only if you need very old consumers.

FEP-0151 (2025 edition)

FEP-0151 (FINAL, March 2026) is the current guidance on NodeInfo in fediverse software — a revised version of the 2020 FEP-f1d5. Key rules:

• Treat software.name and software.version as opaque strings: you MUST NOT infer capabilities from them (version info MAY be used to block software with known vulnerabilities).
• Servers that want to hide usage statistics SHOULD publish an empty usage.users object rather than skewed numbers.
• For capability discovery, prefer protocol-level mechanisms such as FEP-844e over NodeInfo.

Common Software Names

Software	Name Value
Mastodon	mastodon
Pleroma	pleroma
Pixelfed	pixelfed
Lemmy	lemmy
PeerTube	peertube
Misskey	misskey
GoToSocial	gotosocial

Protocols

Protocol	Description
activitypub	ActivityPub federation
diaspora	Diaspora protocol
ostatus	OStatus (legacy)
zot	Zot protocol (Hubzilla)

Usage by Federation Tools

NodeInfo is used by:

• FediDB - Statistics
• Instance pickers and directories

Metadata Extensions

metadata is free-form. FEP-0151 lists the widely used keys: nodeName, nodeDescription, staffAccounts (actor IDs) and federation.enabled:

{
  "metadata": {
    "nodeName": "My server",
    "nodeDescription": "My server",
    "staffAccounts": ["https://social.example/actors/1"],
    "federation": { "enabled": true }
  }
}

Other keys vary by software. Misskey, for example, publishes maintainer, langs, tosUrl, privacyPolicyUrl, repositoryUrl, feedbackUrl and more (from misskey.io's /nodeinfo/2.1). Treat anything outside FEP-0151's list as software-specific.

Caching

NodeInfo can be cached:

res.set('Cache-Control', 'public, max-age=1800'); // 30 minutes

Testing

# Fetch discovery document
curl https://mastodon.social/.well-known/nodeinfo

# Fetch NodeInfo
curl https://mastodon.social/nodeinfo/2.0

Next Steps

• Server Software - Fediverse platforms
• Building an Actor - Full implementation