Kind 17: Reaction to a Website

Overview

Reaction to a Website events (kind 17) allow users to express reactions to external web content. Similar to kind 7 reactions for Nostr events, these events enable users to react with likes, emojis, or other expressions to specific websites or web pages.

Specification

Property	Value
Kind Number	17
Event Range	Regular
Defined in	NIP-25

Content Format

The content field determines the type of reaction:

• + or empty string: A "like" or "upvote"
• -: A "dislike" or "downvote"
• Emoji or custom emoji: A specific reaction using that emoji

Schema

// Like
"content": "+"

// Dislike
"content": "-"

// Emoji reaction
"content": "⭐"

// Custom emoji (NIP-30)
"content": ":soapbox:"

Tags

Tag Name	Description	Format	Required
r	URL of the website being reacted to	["r", "https://example.com/page"]	Yes
emoji	Custom emoji definition	["emoji", "shortcode", "url"]	Conditionally

Client Behavior

Clients should:

1. Display website reactions when viewing information about external web content
2. Interpret + and empty string as likes/upvotes
3. Interpret - as dislikes/downvotes
4. Display emoji reactions appropriately, including rendering custom emoji
5. When creating website reactions:
   • Include a normalized URL in the r tag
   • For custom emoji reactions, include an emoji tag

Relay Behavior

Relays should:

1. Store website reaction events alongside regular events
2. Make reactions discoverable via r tag filters

Use Cases

• Expressing approval/disapproval of external web content
• Bookmarking interesting websites with a star reaction
• Building curated lists of web content based on reactions
• Creating social proof for popular web content
• Recommending websites to followers

Example

// Simple star rating for a website
{
  "id": "4376c65d2f232afbe9b882a35baa4f6fe8667c4e684749af565f981833ed6a65",
  "pubkey": "79dff8f82963424e0bb02708a22e44b4980893e3a4be0fa3cb60a43b946764e3",
  "created_at": 1671217411,
  "kind": 17,
  "tags": [
    ["r", "https://example.com/interesting-article"]
  ],
  "content": "⭐",
  "sig": "908a15e46fb4d8675bab026fc230a0e3542bfade63da02d542fb78b2a8513fcd0092619a2c8c1221e581946e0191f2af505dfdf8657a414dbca329186f009262"
}

// Custom emoji reaction
{
  "id": "5d83da77af1dec6d7289834998ad7aafbd9e2191396d75ec3cc27f5a77226f36",
  "pubkey": "f7234bd4c1394dda46d09f35bd384dd30cc552ad5541990f98844fb06676e9ca",
  "created_at": 1671217500,
  "kind": 17,
  "tags": [
    ["r", "https://example.com/great-resource"],
    ["emoji", "thumbsup", "https://example.com/emoji/thumbsup.png"]
  ],
  "content": ":thumbsup:",
  "sig": "a76f39224cebd44cf04eeebe01d5ab2e8f7a3e5e56c83cadd252e7bc5e2e34fd7ad7148cf7a2c7620d9490ccf2e1bac521995725f2e1f543159b8eb98bfdd405"
}

URL Normalization

URLs in the r tag should be normalized according to RFC 3986 to ensure reactions to the same website can be properly aggregated. This means:

1. Converting the hostname to lowercase
2. Removing default ports (e.g., :80 for HTTP and :443 for HTTPS)
3. Resolving path segments like "./" and "../"
4. Converting percent-encoded sequences to uppercase
5. Decoding percent-encoded sequences that represent unreserved characters

A fragment (e.g., #section1) may be included to react to a specific section of the page, but note that a URL with a fragment is considered different from the same URL without the fragment.

References

• NIP-25: Reactions
• NIP-30: Custom Emoji

Related Kinds

• Kind 7: Reaction - For reacting to Nostr events

Notes

• Website reactions are similar to kind 7 reactions but target external web content rather than Nostr events.
• A URL with a fragment is considered a different target than the same URL without the fragment.
• Single emoji reactions are recommended for clarity and simplicity.
• Custom emoji must be defined using the emoji tag when used.
• The content can contain only one emoji or custom emoji shortcode for clarity.