Kind 10009: Simple Groups

Overview

Simple Groups events (kind 10009) allow users to maintain a list of NIP-29 groups they participate in. This standard replaceable event kind serves as a record of user's group memberships, making it easier to organize and access private group conversations. Unlike public chat channels, these are typically smaller, more private group conversations with specific membership requirements.

Specification

Property	Value
Kind Number	10009
Event Range	Replaceable
Defined in	NIP-51

Content Format

The content field can contain encrypted private group memberships using NIP-04 encryption. The encrypted content follows the same structure as the public tags but is only visible to the creator. This allows users to have both public group memberships (in tags) and private ones (encrypted in content).

Schema

For encrypted private groups:

"content": "<NIP-04 encrypted JSON array of tags>"

The encrypted content, when decrypted, would reveal a JSON array of tags:

[
  ["group", "<group-id>", "<relay-url>", "<optional-group-name>"],
  ["r", "<relay-url>"]
]

Tags

Tag Name	Description	Format	Required
group	Group identifier with optional metadata	["group", "<group-id>", "<relay-url>", "<optional-group-name>"]	Yes
r	Additional relay used by the group	["r", "<relay-url>"]	No

Client Behavior

Clients should:

1. Display the user's group memberships in a dedicated section or navigation menu
2. Provide functionality to join (add) or leave (remove) groups
3. Use this list for quick access to the user's groups
4. Handle both public (in tags) and private (encrypted in content) group memberships
5. When displaying the groups list:
   • Show group names when available, otherwise use group IDs
   • Provide quick navigation to group messages
   • Indicate group status (active, new messages, etc.)
6. When retrieving group messages, fetch them from the relays specified in group and r tags
7. When processing encrypted group memberships, decrypt using NIP-04 and the user's keys
8. Maintain the chronological order of groups, with newest additions at the end
9. Support notifications or status indicators for group activity

Relay Behavior

Relays should:

1. Handle kind 10009 events as normal replaceable events
2. Store these events to allow clients to retrieve the user's group memberships
3. Not attempt to interpret or enforce group membership (this is client-side functionality)

Use Cases

• Maintaining a list of private group conversations
• Organizing small-group communications
• Creating a directory of user's social circles
• Providing quick navigation between group conversations
• Synchronizing group membership across devices
• Creating categorized private communication spaces
• Supporting team or project-based discussions

Example

{
  "id": "4e76cbf8548754cbe6603eba0e0a5126337ce648765aed8419dc4d8d8b9fe711",
  "pubkey": "854043ae8f1f97430ca8c1f1a090bdde6488bd5115c7a45307a2a212750ae4cb",
  "created_at": 1699597889,
  "kind": 10009,
  "tags": [
    ["group", "d9fb3f4a600e513faa389c4bc17e11728cb1f00831a832342f83f6a4c3dd4126", "wss://relay.groups.io", "Project Alpha Team"],
    ["r", "wss://relay.nostr.example.com"],
    ["group", "8b1aae5c5ce1625df18ee8af72267cd4052bbff7d17a5e3a7a262a6aa95be846", "wss://relay.groups.io", "Friends Chat"],
    ["r", "wss://purplepag.es"]
  ],
  "content": "TJob1dQrf2ndsmdbeGU+05HT5GMnBSx3fx8QdDY/g3NvCa7klfzgaQCmRZuo1==?iv=S3rFeFr1gsYqmQA7bNnNTQ==",
  "sig": "a9a4e2192eede77e6c9d24ddfab95ba3ff7c03fbd07ad011fff245abea431fb4d3787c2d04aad001cb039cb8de91d83ce30e9a94f82ac3c5a2372aa1294a96bd"
}

References

• NIP-51: Lists
• NIP-29: Simple Group Chat
• NIP-04: Encrypted Direct Messages

Related Kinds

• Kind 10005: Public Chats - Public chat channel memberships (NIP-28)
• Kind 10: Group Chat Threaded Reply - Messages in group threads
• Kind 12: Group Thread Reply - Replies to threads in group chats

Notes

• Simple Groups list is one of several standard list types defined in NIP-51
• Users can only have one simple groups list (since it's a replaceable event)
• The group IDs referenced conform to the NIP-29 specification for simple group chats
• Group privacy can be managed by choosing whether to use public tags or encrypted content
• For sensitive groups, memberships should be stored in the encrypted content field
• Relay hints in the group tags and r tags are essential for finding group messages
• Additional r tags can specify supplemental relays used by the group
• The optional group name parameter helps with displaying human-readable group labels
• NIP-29 groups are different from NIP-28 channels; they're typically smaller and more private