NIP-25 defines reactions as kind 7 events. It gives clients a shared event form for attaching an emoji or other short reaction to a note, article, listing, or other referenced event.

How It Works

A reaction event carries its reaction text in content and references the target through the target event’s e tag. When the target is addressable, the reaction also includes its a tag. It also includes p tags for the referenced event’s author, which lets relays and clients route notifications without inferring recipients from the event content.

The default reaction is +, so clients can treat an empty reaction content as a positive response. Other emoji are valid reaction values. The specification also permits - for a negative reaction, which the July 2022 follow-up added after the original introduction.

Clients should preserve the target reference and author tags when creating a reaction. A reaction is an ordinary signed event, so it can travel through normal relay subscriptions and be rendered by any client that recognizes kind 7.

Implementations

NIP-25 is widely implemented by Nostr clients and libraries as part of ordinary note interaction. Its simple kind-and-tags model lets clients display counts, individual reactions, and notifications without a separate transport protocol.

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