NIP-25

Reactions (kind 7) - allows users to react to events with a + (like), - (dislike), or custom emoji/text content. Reactions reference the target event by its ID and the target author's pubkey.

Import

import { nip25 } from 'nostr-core'
// or import individual functions
import {
  createReactionEventTemplate,
  createReactionEvent,
  parseReaction,
} from 'nostr-core'

Reaction Type

type Reaction = {
  targetEvent?: { id: string; pubkey: string; kind?: number }
  targetAddress?: string
  content: string
}

Field	Type	Description
targetEvent	{ id: string; pubkey: string; kind?: number } (optional)	The event being reacted to
targetAddress	string (optional)	Replaceable event address (kind:pubkey:d-tag)
content	string	Reaction content: '+', '-', or custom emoji/text

nip25.createReactionEventTemplate

function createReactionEventTemplate(reaction: Reaction): EventTemplate

Creates an unsigned kind 7 reaction event template. Use with finalizeEvent() or pass to a Signer.

Parameter	Type	Description
reaction	Reaction	Reaction target and content

Returns: EventTemplate - Unsigned kind 7 event with e, p, k, and optionally a tags.

const template = nip25.createReactionEventTemplate({
  targetEvent: {
    id: 'target-event-id',
    pubkey: 'target-author-pubkey',
    kind: 1,
  },
  content: '+',
})

const signed = await signer.signEvent(template)

nip25.createReactionEvent

function createReactionEvent(reaction: Reaction, secretKey: Uint8Array): NostrEvent

Creates and signs a kind 7 reaction event.

Parameter	Type	Description
reaction	Reaction	Reaction target and content
secretKey	Uint8Array	Signer's secret key (32 bytes)

Returns: NostrEvent - Signed kind 7 reaction event ready to publish.

// Like a post
const like = nip25.createReactionEvent(
  {
    targetEvent: { id: 'event-id', pubkey: 'author-pubkey', kind: 1 },
    content: '+',
  },
  secretKey,
)
await pool.publish(['wss://relay.example.com'], like)

// React with custom emoji
const fire = nip25.createReactionEvent(
  {
    targetEvent: { id: 'event-id', pubkey: 'author-pubkey', kind: 1 },
    content: '\u{1F525}',
  },
  secretKey,
)

nip25.parseReaction

function parseReaction(event: NostrEvent): {
  targetEventId?: string
  targetPubkey?: string
  targetKind?: number
  targetAddress?: string
  content: string
  isPositive: boolean
  isNegative: boolean
  emoji?: string
}

Parses a kind 7 reaction event into its components.

Parameter	Type	Description
event	NostrEvent	A kind 7 reaction event

Returns: Object with target references, content, and convenience flags.

Return Field	Type	Description
targetEventId	string (optional)	ID of the target event
targetPubkey	string (optional)	Pubkey of the target author
targetKind	number (optional)	Kind of the target event
targetAddress	string (optional)	Target replaceable event address
content	string	Reaction content
isPositive	boolean	true if content is '+' or empty
isNegative	boolean	true if content is '-'
emoji	string (optional)	The emoji/text if not a simple + or -

const parsed = nip25.parseReaction(reactionEvent)
console.log(parsed)
// {
//   targetEventId: 'event-id',
//   targetPubkey: 'author-pubkey',
//   targetKind: 1,
//   content: '+',
//   isPositive: true,
//   isNegative: false,
//   emoji: undefined
// }

Full Example

import { generateSecretKey, getPublicKey, nip25, RelayPool } from 'nostr-core'

const sk = generateSecretKey()
const pk = getPublicKey(sk)
const pool = new RelayPool()

// Like a post
const like = nip25.createReactionEvent(
  {
    targetEvent: { id: 'note-id', pubkey: 'note-author', kind: 1 },
    content: '+',
  },
  sk,
)
await pool.publish(['wss://relay.example.com'], like)

// Dislike a post
const dislike = nip25.createReactionEvent(
  {
    targetEvent: { id: 'note-id', pubkey: 'note-author', kind: 1 },
    content: '-',
  },
  sk,
)

// React to a long-form article by address
const articleReaction = nip25.createReactionEvent(
  {
    targetAddress: '30023:author-pubkey:article-slug',
    content: '\u{1F44D}',
  },
  sk,
)

// Fetch and parse reactions on a note
const reactions = await pool.querySync(
  ['wss://relay.example.com'],
  { kinds: [7], '#e': ['note-id'] },
)

let likes = 0
let dislikes = 0
const customReactions: string[] = []

for (const event of reactions) {
  const parsed = nip25.parseReaction(event)
  if (parsed.isPositive) likes++
  else if (parsed.isNegative) dislikes++
  else if (parsed.emoji) customReactions.push(parsed.emoji)
}

console.log(`Likes: ${likes}, Dislikes: ${dislikes}`)
console.log(`Custom reactions: ${customReactions.join(' ')}`)

pool.close()

How It Works

• Kind 7 events are reactions to other events
• Content '+' or empty string means a like/upvote
• Content '-' means a dislike/downvote
• Any other content is a custom reaction (emoji or text)
• The e tag references the target event ID
• The p tag references the target event author's pubkey
• The k tag optionally specifies the kind of the target event
• The a tag can reference a replaceable event by address instead of (or in addition to) event ID
• Clients typically count reactions per event and display them as like counts or emoji summaries
• A user can have multiple reactions to the same event (e.g., both a like and an emoji)