Nostr website screenshot

Nostr

Nostr (Notes and Other Stuff Transmitted by Relays) is an open, permissionless protocol for censorship-resistant social and messaging applications. Identity is a public/private keypair; content is a signed JSON event; transport is a WebSocket connection to one or more relays. There is no central server, no canonical API, and no organization that owns the protocol — only a set of community-defined NIPs (Nostr Implementation Possibilities) describing event kinds, relay behavior, and client conventions. A large ecosystem of clients (Damus, Amethyst, Coracle, Yakihonne, Nostur, Iris), relay implementations (strfry, nostream, khatru), and language libraries (nostr-tools for JS, python-nostr, go-nostr, rust-nostr, NDK) has formed around the protocol. Nostr is profiled here through its specifications and reference implementations rather than a vendor API.

Nostr is listed with 4 APIs on the APIs.io network, including Protocol (NIP-01), Relay WebSocket Interface, and 2 more. Tagged areas include Nostr, Decentralized Social, Open Protocol, Relay, and WebSocket.

The Nostr catalog on APIs.io includes 1 event-driven AsyncAPI specification and 1 Spectral governance ruleset.

Nostr’s developer surface includes getting-started guide and 16 more developer resources.

22.3/100 emerging ▬ flat Agent 15/100 agent aware Front door AI 1/6 silent Heartbeat 93/100 alive self hosted · Unlicense Full breakdown ↓
scored 2026-11-06 · rubric v0.27.0 · Show this score on your site →
AccessFree
4 APIs
NostrDecentralized SocialOpen ProtocolRelayWebSocketSigned EventsNIPCensorship ResistantSelf-Sovereign IdentityReal-Time

Kin Score

Kin Score Kin Score How this is scored →
scored 2026-11-06 · rubric v0.27.0
Regulatory Posture applies to this provider. Its tags matched the Horizontal (data, software, accessibility, platform) regime, so Regulatory Posture carries 15 points of the composite. If this regime is wrong for your business, say so on your provider repo — the applicability map is public and we will correct it.
Open Source Surface applies to this provider. This product is open source and we read its repository directly, so Open Source Surface carries 10 points of the composite. It is scored from what the repository actually publishes — a security policy, a contribution guide, a release history, a code of conduct — read live from the provider rather than inferred from our own catalog pointers. This facet adds; nothing was taken away to make room for it. An open-source project is not excused from the commercial facets, because exemption would strip it of the points it does earn. If we have the wrong repository, or this product is not open source, say so on your provider repo and we will drop the facet rather than have you publish against it.
Create-or-Update Ergonomics could not be measured. We hold no machine-readable contract for this provider to read, so there is nothing to measure a write surface against. Excluded rather than scored zero: never-measured and measured-empty are different facts. Publishing an OpenAPI is what makes this facet — and several others — scorable at all.
The six quality facets above are damped to 75 points between them, because both conditional facets apply and carry 25 points together. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 75% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.
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Agent readiness — checks not met, largest first (exact, from this profile):
  • MCP Server +12 pts — deployment.mode + probe verdict on the mcp/ manifest, not the pointer; an unprobed slug falls back to authorship
  • Agentic Access Contract +10 pts — agentic_access artifact present (x-agentic-access), graded by author
  • Machine-Readable Auth +10 pts — a served openid-configuration/oauth-authorization-server carrying `issuer` (served), else the securitySchemes class in the provider OpenAPIs — bound (mutualTLS, DPoP, Signature) > negotiable (oauth2 authorizationCode/clientCredentials, openIdConnect) > bearer (http bearer, apiKey)
  • Idempotency +9 pts — OpenAPI mutating operations declare an idempotency key — a header, a request-body property, or a named de-duplication token whose own description says so (verified); else common[].type matches /idempoten/i (documented)
  • Stable Error Semantics +8 pts — OpenAPI $refs a shared error schema across 4xx/5xx responses (verified), else common[].type includes ErrorCatalog / ErrorCodes / DeclineCodes
  • A2A Agent Card +8 pts — a2a/-a2a.yml manifest, graded on conformance.grade against A2A 1.0.0
10 more unmet checks in the Agent Readiness table above.
Kin Score — facets with the most composite points still available (weight × headroom):
Each check links to what satisfies it. Publish the artifact, or tell us where it already lives, and the score moves on the next scoring run.
Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from the provider profile at artifacts.apis.io/nostr/apis.yml: open an issue on github.com/api-evangelist/nostr to ask a question or point us at an artifact you publish. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

Markets this provider is in provisional

The Kin Score Market layer reads a provider inside its market: its position, and how deep its integrations go. Depth is only comparable within a position. Provisional and unweighted: not part of the Kin Score or agent readiness.

MarketPositionDepthRegistered MCP serverDeclares compatibility
Obsidian Community Plugins (third-party APIs the Obsidian plugin ecosystem integrates) unknown 2.5 (thin) - -

Registered MCP server and declares compatibility are report only — not weighted. Undeclared means we found nothing we can read, so there is no number: we never infer integrations.

Standards implemented 2

Standards this provider implements or carries. De facto ones are profiled and measured by the API Commons; formal ones come from the standards directory and are linked by the provider's own tags. The evidence column says how each claim was established — not that it was made.

tagged — the provider's own APIs.json carries the standard as a tag; implementation not verified
measured — observed by APIs.io (published)

APIs 4

Individual APIs this provider publishes, each with its own machine-readable definition.

Nostr Protocol (NIP-01)

NIP-01 defines the core Nostr protocol: event format (id, pubkey, created_at, kind, tags, content, sig), client-to-relay messages (EVENT, REQ, CLOSE), and relay-to-client messag...

Nostr Implementation Possibilities (NIPs)

NIPs are the standards documents that extend Nostr beyond the core protocol. They define event kinds (text notes, reactions, zaps, long-form articles, DMs, calendar events, mark...

Nostr Relay WebSocket Interface

A Nostr relay is a WebSocket server that accepts signed events, stores them subject to its own policy, and responds to subscription filters from clients. The relay surface is in...

nostr-tools JavaScript Library

nostr-tools is the de-facto JavaScript/TypeScript library for Nostr clients and bots. It implements event creation, signing, relay connections, subscription filters, and many co...

Nostr API pricing

Not yet checked against Nostr's own pricing page. Compiled by API Evangelist on 2026-05-22; confirm before you rely on a figure. A free plan or tier is listed.

PlanPrice
Free freemium Free

Plan details, limits and sources →

Rate limits

Compiled by API Evangelist, not yet checked against Nostr's documentation. Rate-limit details →

Pricing Plans 1

Published pricing tiers and plan structures.

Nostr Plans Pricing

1 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Nostr Rate Limits

2 limits

RATE LIMITS

FinOps 1

Cost, billing, and metering signals for API financial operations.

Nostr Finops

FINOPS

Event Specifications 1

AsyncAPI definitions for this provider's event-driven and streaming APIs.

Nostr Relay Protocol

AsyncAPI definition of the canonical Nostr relay-client protocol as specified by NIP-01 (basic protocol) and NIP-42 (authentication). Nostr relays expose a single WebSocket endp...

ASYNCAPI

Spectral Rules 1

Spectral governance rulesets for linting and validating these APIs.

Nostr — asyncapi rules

6 rules · 1 errors 5 warnings

SPECTRAL

Security Posture 1

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Nostr Domain Security

TLSv1.3

SECURITY

Resources

Get Started 1

Portal, sign-up, and the first successful call

Documentation 2

Reference material describing how the API behaves

Agent Surfaces 1

MCP servers, agent skills, and machine-readable catalogs

Build 1

SDKs, sample code, and the tooling you integrate with

Access & Security 1

Authentication, authorization, and security posture

Operate 3

Status, limits, changes, and where to get help

Commercial 3

Pricing, plans, and the legal terms of use

Company 1

The organization behind the API

Other 4

Properties that don't map to a standard resource type

Source (apis.yml)

apis.yml Raw ↑
aid: nostr
name: Nostr
description: 'Nostr (Notes and Other Stuff Transmitted by Relays) is an open,

  permissionless protocol for censorship-resistant social and messaging

  applications. Identity is a public/private keypair; content is a signed

  JSON event; transport is a WebSocket connection to one or more relays.

  There is no central server, no canonical API, and no organization that

  owns the protocol — only a set of community-defined NIPs (Nostr

  Implementation Possibilities) describing event kinds, relay behavior,

  and client conventions. A large ecosystem of clients (Damus, Amethyst,

  Coracle, Yakihonne, Nostur, Iris), relay implementations (strfry,

  nostream, khatru), and language libraries (nostr-tools for JS,

  python-nostr, go-nostr, rust-nostr, NDK) has formed around the protocol.

  Nostr is profiled here through its specifications and reference

  implementations rather than a vendor API.

  '
type: Index
deliveryModel:
  model: self-hosted
  license: Unlicense
  open_source: true
  commercial: false
  callable_host: false
  label: Self-hosted open source · you run it yourself
  confidence: high
  source:
  - license
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: free
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Free
  confidence: low
  source:
  - plans
  - security
  generated: '2026-11-06'
  method: derived
position: Protocol
access: Public
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/nostr.png
tags:
- Nostr
- Decentralized Social
- Open Protocol
- Relay
- WebSocket
- Signed Events
- NIP
- Censorship Resistant
- Self-Sovereign Identity
- Real-Time
tags_raw:
- Nostr
- Decentralized Social
- Open Protocol
- Relays
- WebSocket
- Signed Events
- NIP
- Censorship Resistant
- Self-Sovereign Identity
- Real-Time
url: https://raw.githubusercontent.com/api-evangelist/nostr/refs/heads/main/apis.yml
created: '2026-05-23'
modified: '2026-05-29'
specificationVersion: '0.23'
apis:
- aid: nostr:nostr-protocol
  name: Nostr Protocol (NIP-01)
  description: 'NIP-01 defines the core Nostr protocol: event format (id, pubkey,

    created_at, kind, tags, content, sig), client-to-relay messages

    (EVENT, REQ, CLOSE), and relay-to-client messages (EVENT, OK, EOSE,

    CLOSED, NOTICE) exchanged over a single WebSocket connection. This

    is the minimum surface every client and relay must implement.

    '
  humanURL: https://github.com/nostr-protocol/nips/blob/master/01.md
  baseURL: wss://relay.example
  tags:
  - NIP-01
  - Event
  - WebSocket
  - Subscription
  - Signature
  properties:
  - type: Specification
    url: https://github.com/nostr-protocol/nips/blob/master/01.md
  - type: SpecificationIndex
    url: https://github.com/nostr-protocol/nips
  - type: AsyncAPI
    url: https://raw.githubusercontent.com/api-evangelist/nostr/refs/heads/main/asyncapi/nostr-asyncapi.yml
  - type: Repository
    url: https://github.com/nostr-protocol
- aid: nostr:nostr-nips
  name: Nostr Implementation Possibilities (NIPs)
  description: 'NIPs are the standards documents that extend Nostr beyond the core

    protocol. They define event kinds (text notes, reactions, zaps,

    long-form articles, DMs, calendar events, marketplaces), client

    behaviors (NIP-05 verified handles, NIP-07 browser signers, NIP-46

    remote signers), and relay capabilities (NIP-11 relay information,

    NIP-42 authentication). Conformance is informal — clients and relays

    pick the NIPs they support.

    '
  humanURL: https://github.com/nostr-protocol/nips
  baseURL: https://github.com/nostr-protocol/nips
  tags:
  - NIPs
  - Event Kinds
  - Extensions
  - Standards
  properties:
  - type: SpecificationIndex
    url: https://github.com/nostr-protocol/nips
  - type: Repository
    url: https://github.com/nostr-protocol
- aid: nostr:relay-interface
  name: Nostr Relay WebSocket Interface
  description: 'A Nostr relay is a WebSocket server that accepts signed events,

    stores them subject to its own policy, and responds to subscription

    filters from clients. The relay surface is intentionally minimal:

    no accounts, no shared state, no canonical ordering. Operators

    choose retention, content policy, paid-access, and authentication

    (NIP-42) independently. Reference implementations include strfry

    (C++), nostream (TypeScript), and khatru (Go).

    '
  humanURL: https://github.com/nostr-protocol/nips/blob/master/11.md
  baseURL: wss://relay.example
  tags:
  - Relay
  - WebSocket
  - strfry
  - khatru
  - nostream
  properties:
  - type: Specification
    url: https://github.com/nostr-protocol/nips/blob/master/01.md
  - type: RelayInfo
    url: https://github.com/nostr-protocol/nips/blob/master/11.md
  - type: AsyncAPI
    url: https://raw.githubusercontent.com/api-evangelist/nostr/refs/heads/main/asyncapi/nostr-asyncapi.yml
  - type: ReferenceImplementation
    url: https://github.com/hoytech/strfry
  - type: ReferenceImplementation
    url: https://github.com/Cameri/nostream
  - type: ReferenceImplementation
    url: https://github.com/fiatjaf/khatru
- aid: nostr:nostr-tools
  name: nostr-tools JavaScript Library
  description: 'nostr-tools is the de-facto JavaScript/TypeScript library for Nostr

    clients and bots. It implements event creation, signing, relay

    connections, subscription filters, and many common NIPs, and is

    used by a large portion of the Nostr web ecosystem.

    '
  humanURL: https://github.com/nbd-wtf/nostr-tools
  baseURL: https://www.npmjs.com/package/nostr-tools
  tags:
  - SDK
  - JavaScript
  - TypeScript
  - Client Library
  properties:
  - type: Repository
    url: https://github.com/nbd-wtf/nostr-tools
  - type: Package
    url: https://www.npmjs.com/package/nostr-tools
features:
- name: Cryptographic Identity
  description: Each user is a secp256k1 keypair; no account creation, no central registry.
- name: Signed Events
  description: Every event carries a Schnorr signature over a deterministic JSON serialization, allowing any relay to verify
    authenticity.
- name: Multi-Relay Publishing
  description: Clients publish to and read from many relays in parallel, with no single point of failure.
- name: Extensible Event Kinds
  description: New event kinds and NIPs can be proposed and adopted without coordination from a central authority.
- name: Censorship Resistance
  description: Relays can refuse content, but they cannot prevent it from existing elsewhere on the network.
- name: Lightweight Relay Surface
  description: A minimal WebSocket interface keeps the cost of running a relay low enough for hobbyists.
useCases:
- name: Social Clients
  description: Build mobile, web, or desktop social clients (Damus, Amethyst, Coracle, Yakihonne).
- name: Long-Form Publishing
  description: Use NIP-23 long-form events for blog-style content and newsletter distribution.
- name: Private Messaging
  description: Implement encrypted direct messages and group chat using NIP-04, NIP-17, and NIP-44 kinds.
- name: Lightning Zaps
  description: Layer Lightning Network micropayments on top of Nostr events using NIP-57 zaps.
- name: Relay Operation
  description: Run a public, private, or paid relay to serve specific communities or content policies.
- name: Bots and Automation
  description: Build read-only bots, scrapers, and event mirrors with minimal infrastructure.
integrations:
- name: Damus
- name: Amethyst
- name: Coracle
- name: Yakihonne
- name: Nostur
- name: Iris
- name: strfry
- name: khatru
- name: nostream
- name: Lightning Network
common:
- type: Plans
  url: plans/nostr-plans-pricing.yml
- type: RateLimits
  url: rate-limits/nostr-rate-limits.yml
- type: FinOps
  url: finops/nostr-finops.yml
- type: IssueTracker
  url: https://github.com/nbd-wtf/nostr-tools/issues
- type: Releases
  url: https://github.com/nbd-wtf/nostr-tools/releases
- type: License
  name: Unlicense
  url: https://github.com/nbd-wtf/nostr-tools/blob/master/LICENSE
- type: DomainSecurity
  url: security/nostr-domain-security.yml
- type: Website
  url: https://nostr.com/
- type: GitHubOrganization
  url: https://github.com/nostr-protocol
- type: Specification
  url: https://github.com/nostr-protocol/nips
- type: ProtocolReference
  url: https://github.com/nostr-protocol/nostr
- type: AppDirectory
  url: https://nostrapps.com/
- type: SoftwareDirectory
  url: https://nostr.net/
- type: GettingStarted
  url: https://start.njump.me/
- type: NetworkExplorer
  url: https://nostr.band/
- type: OriginalEssay
  url: https://fiatjaf.com/nostr.html
- type: LlmsText
  url: https://nostr.com/llms.txt
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com

Nostr API — frequently asked questions

Does Nostr have an API?

Yes. APIs.io lists 4 APIs from Nostr, including Nostr Protocol (NIP-01), Nostr Implementation Possibilities (NIPs) and Nostr Relay WebSocket Interface, and 1 more.

How much does the Nostr API cost?

APIs.io lists 1 pricing plan for Nostr, with each plan's price, limits and inclusions under Pricing on this page.

Is the Nostr API ready for AI agents?

Nostr has a Kin Score of 22.3 out of 100 (emerging) and an Agent Readiness score of 14.7 (agent-aware), scored by API Evangelist on 2026-11-06.

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