MCP.Market

Nostr Signer MCP server

online · 100% uptime
by signer.frontiercrown.com·com.frontiercrown.signer/nostr-signer·v0.4.0
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Approve Nostr signatures with your own browser signer without exposing a private key.

B77/100grade B
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If you have run it, two minutes of your experience saves the next person an afternoon.

Nostr Signer tools (17, 3 write)

write = sends, deletes, buys or posts
  • approve_grynvault_browser_handoffFree

    Sign a short-lived, read-only Grynvault account handoff code so the browser tab that created it can receive its own dashboard. This does not create an invoice, publish a Nostr event, change settlement, or grant wallet custody.

  • begin_nostrconnect_pairingFree

    Advanced fallback: create a nostrconnect:// URI for the user to scan or open in a remote signer. Never accepts an nsec.

  • connect_bunkerFree

    Connect a bunker:// URI only when the user knowingly supplied it. Prefer the local setup page so connection secrets are not placed in chat. Never accepts an nsec.

  • create_grynvault_nip05_invoicewrite actionFree

    After separate explicit user confirmation, sign the prepared authorization and create exactly one pending 2,000-sat name@frontiercrown.com invoice. Does not pay, settle, activate, or prove identity.

  • create_grynvault_supporter_invoicewrite actionFree

    After separate explicit user confirmation, sign the prepared authorization and create exactly one pending Grynvault supporter invoice. Does not pay it and never treats a redirect as settlement.

  • disconnect_signerFree

    Forget the in-memory signer session and all prepared events.

  • get_grynvault_account_dashboardFree

    Read the connected Nostr identity's Grynvault supporter, payment, and NIP-05 dashboard using a short-lived signed authorization. This does not create an invoice or change settlement.

  • get_public_keyFree

    Return the public key exposed by the currently paired signer.

  • get_setup_urlFree

    Return the loopback-only page used to connect a NIP-07 browser extension or an advanced NIP-46 signer.

  • get_signer_statusFree

    Check whether a user-controlled NIP-07 or NIP-46 signer is connected.

  • prepare_eventFree

    Validate and bind an exact unsigned Nostr event for user review. This does not sign or publish. Show the user every field before requesting a signature.

  • prepare_grynvault_nip05_invoiceFree

    Check and normalize a name@frontiercrown.com identifier, then prepare its exact 2,000-sat invoice authorization. Does not sign, reserve the name, create, pay, or settle an invoice.

  • prepare_grynvault_supporter_invoiceFree

    Prepare an exact, short-lived signed-authorization request for a one-time donation of 21 to 1,000,000 sats or the fixed 2,100-sat 30-day membership. Does not sign, create, pay, or settle an invoice.

  • prepare_noteFree

    Prepare and bind an exact unsigned kind:1 note for user review. This does not sign or publish.

  • publish_eventwrite actionFree

    Publish a previously verified signed event to configured relays. Requires separate explicit user intent.

  • query_eventsFree

    Read a bounded set of verified public profile or note events from selected relays.

  • sign_eventFree

    Ask the paired signer to approve and sign the exact event bound to a fresh intent. Requires explicit user intent and never publishes.

Public scan report

scanner v0.1.10 · 2026-10-14 · same rubric, same numbers if you re-run it

1 high
  • –Code scanremote-only server, no package to scann/a
  • Live reliabilityremote reachable in 241ms20/20
  • Tool poisoning17 tool descriptions checked15/15
  • Auth qualityopen endpoint exposes 3 write-action tools with no auth3/15
  • Maintenancelast push 33 days ago12/15
  • Maintainer identityendpoint served from the registry-verified namespace domain8/10

Findings (1)

  • highWrite-action tools reachable without authenticationauth.open-write
Overall 77/100. Components that don't apply are left out of the denominator. Any critical finding is an F.RubricAppeal a findingJSON

How Nostr Signer compares

Against every graded Scraping and browsing MCP server, from our own scans and uptime checks. Updated after each scan run.

Safety score
77/100
higher than 50% of 866 Scraping and browsing servers
Tools
17
the typical Scraping and browsing server has 6
Tools that change things
18%
typical: 0%. Fewer write tools means less an agent can break
Uptime
100%
of our recent checks; the typical remote Scraping and browsing server answers 100%
Response time
442 ms
faster than 25% of 384 Scraping and browsing servers

What its tools let an agent do: 13 read · 2 create · 1 change · 1 send or post

Install Nostr Signer in Claude Code, Cursor or VS Code

claude mcp add --transport http nostr-signer https://signer.frontiercrown.com/mcp
Add to Cursor

What the publisher says

From the Nostr Signer repository's README, as published. We do not edit it. Read it on GitHub

Nostr Signer for ChatGPT and Codex

A local-first, open-source signer bridge that lets ChatGPT Work or Codex request Nostr signatures from Alby, nos2x, another NIP-07 browser extension, or an advanced NIP-46 remote signer. The signer keeps the private key. This project never needs, accepts, stores, logs, or transmits an nsec.

Use the local installation for the strongest security. It keeps the approval page and session

coordinator on your computer. The hosted bridge is a convenience beta: event contents, public keys,

signatures, ciphertext, and relay responses transit infrastructure operated by Frontier Crown on

Railway. Hosted NIP-44 encryption and decryption are disabled because plaintext could otherwise

transit that infrastructure.

Release status: v0.4.0 local public beta plus a live accountless hosted alpha. Live Chrome-family NIP-07 public-key access and signing succeeded on 2026-09-10. A user-approved announcement was accepted and independently read back with a valid signature from nos.lol, nostr.mom, and relay.primal.net. The hosted MCP endpoint at https://signer.frontiercrown.com/mcp completed external initialization and two-session pairing-page isolation tests. Its reduced hosted surface exposes 17 tools and omits NIP-44 encrypt/decrypt. It is active in the official MCP Registry but has not been approved by the OpenAI directory.

Will it work for everyone?

Not universally. The current release is for desktop users who can run Node.js 22+, connect a local stdio MCP server, and open the approval page in a Chrome- or Firefox-family profile with a compatible NIP-07 extension. It is not a mobile signer or unattended signing daemon. Prefer a signer that displays the complete event—including kind, content, tags, and timestamp—before every approval.

The free local plugin is the primary, recommended public release because each user keeps the key and runs the bridge. It needs no OAuth or separate account: the browser extension supplies the Nostr public key and approves each signature. The hosted prototype also has no OAuth or user accounts: it binds each AI MCP session to an extension-enabled browser with a short-lived, high-entropy capability URL. It still needs per-session isolation, abuse controls, privacy/retention operations, and an independent security review. See LAUNCHREADINESS.md, COMPATIBILITY.md, and HOSTEDSERVICE.md.

Install in Codex

Clone the public source, verify the release tag, build it locally, and register the bundled MCP server. Then start a new Codex task so its tools are loaded:

git clone --branch v0.4.0 https://github.com/hudhaifahz/nostr-signer-chatgpt.git
cd nostr-signer-chatgpt
npm ci
npm run check
codex mcp add nostr-signer -- node "$PWD/mcp/server.mjs"

The repository includes portable plugin manifests, but a one-command Grynvault marketplace wrapper is not published yet. Inspect the source and release tag before installing; the local signer bridge runs with the permissions of the desktop user who starts it.

Download the prebuilt local bundle

The release page includes a prebuilt archive and SHA-256 checksum. It contains the standalone MCP bundle, plugin manifests, signer skill, license notices, source, tests, and documentation. It does not contain a private key, signer session, or browser data.

Build hashes and the live deployment's claimed source revision are documented in PROVENANCE.md and published at https://signer.frontiercrown.com/provenance. Tagged archives receive GitHub build provenance attestations.

Shortened. The full README is on GitHub.

Nothing above is checked by us. What we check is on the safety report.

Nostr Signer: common questions

Is Nostr Signer MCP server safe?
Mostly: it is graded B (77/100). Read the Nostr Signer safety report
How do I install Nostr Signer?
It runs remotely at signer.frontiercrown.com. Add it to Claude Code, Cursor, VS Code or Claude Desktop with the snippets above, or call it through the mcp.market gateway without installing anything.
Does Nostr Signer need an API key?
Not as far as the registry entry and our scan can tell: no credentials are declared or required.
Is Nostr Signer maintained?
The last commit was 54 days ago (2026-09-11). The latest release is v0.4.0.
Is Nostr Signer up?
100% of our last 28 checks got an answer. We check remote servers about four times a day.
What can I use instead of Nostr Signer?
Servers from other publishers that do the same job: Google News MCP server, GrowBlocks Dev Kit MCP server and SeleniumBase MCP server.
How does Nostr Signer compare with other Scraping and browsing MCP servers?
safety score 77/100 (higher than 50% of 866 Scraping and browsing servers); tools 17 (the typical Scraping and browsing server has 6); tools that change things 18% (typical: 0%. Fewer write tools means less an agent can break). Full comparison.

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