NIP-52: Calendar Events

Status: Final Category: Social Features

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Overview

NIP-52 defines how to publish, share, and respond to calendar events on Nostr. It is the basis for any event-listing or scheduling feature in a Nostr client — conference schedules, meetup pages, livestream announcements, and personal calendars.

Three event kinds are introduced:

• kind 31922 — date-based event (an all-day event, no time component)
• kind 31923 — time-based event (specific start and end times)
• kind 31924 — calendar (a collection of events)
• kind 31925 — calendar event RSVP

All four are parameterised replaceable events (see NIP-33), meaning each event has a stable d tag that lets the author update it later without losing references.

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Why It Matters

Before NIP-52, every Nostr client that wanted to surface events had to invent its own format. Amethyst’s calendar, Flockstr’s meetup pages, and various conference companion apps were all incompatible.

NIP-52 standardises the shape so an event published from one client appears correctly in another. A meetup organiser can post once and have it show up across the ecosystem.

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Event Structure

Date-based event (kind 31922)

{
  "kind": 31922,
  "tags": [
    ["d", "unique-id"],
    ["title", "Bitfest UK 2026"],
    ["start", "2026-11-21"],
    ["end", "2026-11-23"],
    ["location", "Manchester, UK"],
    ["t", "bitcoin"], ["t", "nostr"]
  ],
  "content": "UK's first Nostr conference..."
}

Time-based event (kind 31923)

{
  "kind": 31923,
  "tags": [
    ["d", "monthly-london-meetup-april"],
    ["title", "Nostr London Meetup"],
    ["start", "1714155600"],
    ["end", "1714165200"],
    ["start_tzid", "Europe/London"],
    ["location", "Cyphermunk House"]
  ],
  "content": "Monthly London Nostr meetup..."
}

start / end for time-based events use unix timestamps. Date-based events use ISO 8601 date strings without a time component.

RSVP (kind 31925)

{
  "kind": 31925,
  "tags": [
    ["a", "31923:<pubkey>:monthly-london-meetup-april"],
    ["status", "accepted"]
  ]
}

status can be accepted, tentative, or declined.

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Practical Uses

• Conference schedules — each talk is a kind 31923 event linked to a kind 31924 calendar
• Recurring meetups — publish a fresh kind 31923 each month with the same d tag pattern
• Personal calendars — a kind 31924 calendar listing your public commitments
• Livestream announcements — a kind 31923 with a livestream URL in content

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Client Support

• Amethyst (Android) — full calendar UI for browsing and RSVPing to events; v1.06.0 added native calendar with appointment creation
• Flockstr — dedicated event/meetup client built around NIP-52
• YakiHonne — surfaces NIP-52 events alongside long-form content

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Trade-offs and Open Questions

• Time zones — date-based events have no timezone; time-based events use start_tzid but support varies
• Recurrence — there is no native repeat-rule (RRULE) yet; recurring events typically post a new event for each occurrence
• Discovery — without NIP-50 search or curated lists, events scale poorly past local communities

For UK community events that we surface on this site, see the Events directory.

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Related NIPs

• NIP-01 — protocol basics
• NIP-33 — parameterised replaceable events (the foundation NIP-52 builds on)
• NIP-51 — lists (used to bookmark and share calendars)

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Last updated: April 2026 Official specification: GitHub