Nostr Signer is a remote MCP server that gives an AI agent 17 tools, among them approve_grynvault_browser_handoff, begin_nostrconnect_pairing, connect_bunker. It answers at https://signer.frontiercrown.com/mcp over streamable HTTP, and it listed its tools to an anonymous client, so no sign-in was needed for that. Our probes reached it 6 of 6 times since 12 September 2026; the last check, on 24 October 2026, succeeded.
Approve Nostr signatures with your own browser signer without exposing a private key.
Description as the publisher wrote it.
| Tool | What it does |
|---|---|
approve_grynvault_browser_handoff | 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. Inputs: code, confirm_browser_sign_in |
begin_nostrconnect_pairing | Advanced fallback: create a nostrconnect:// URI for the user to scan or open in a remote signer. Never accepts an nsec. Inputs: relays |
connect_bunker | 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. Inputs: connection_uri |
create_grynvault_nip05_invoice | After separate explicit user confirmation, sign the prepared authorization and create exactly one pending 2,000-sat [email protected] invoice. Does not pay, settle, activate, or prove identity. Inputs: operation_id, confirm_invoice_creation |
create_grynvault_supporter_invoice | 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. Inputs: operation_id, confirm_invoice_creation |
disconnect_signer | Forget the in-memory signer session and all prepared events. Inputs: confirm_disconnect |
get_grynvault_account_dashboard | 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. Inputs: confirm_account_access |
get_public_key | Return the public key exposed by the currently paired signer. |
get_setup_url | Return the loopback-only page used to connect a NIP-07 browser extension or an advanced NIP-46 signer. |
get_signer_status | Check whether a user-controlled NIP-07 or NIP-46 signer is connected. |
prepare_event | 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. Inputs: event |
prepare_grynvault_nip05_invoice | Check and normalize a [email protected] identifier, then prepare its exact 2,000-sat invoice authorization. Does not sign, reserve the name, create, pay, or settle an invoice. Inputs: name |
prepare_grynvault_supporter_invoice | 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. Inputs: plan, donation_sats |
prepare_note | Prepare and bind an exact unsigned kind:1 note for user review. This does not sign or publish. Inputs: content |
publish_event | Publish a previously verified signed event to configured relays. Requires separate explicit user intent. Inputs: intent_id, confirm_publish, relays |
query_events | Read a bounded set of verified public profile or note events from selected relays. Inputs: relays, authors, kinds, limit, since |
sign_event | Ask the paired signer to approve and sign the exact event bound to a fresh intent. Requires explicit user intent and never publishes. Inputs: intent_id, confirm_signature |
Every block below points at https://signer.frontiercrown.com/mcp. Pick your client and copy.
claude mcp add --transport http nostr-signer https://signer.frontiercrown.com/mcp
{
"mcpServers": {
"nostr-signer": {
"command": "npx",
"args": ["-y", "mcp-remote", "https://signer.frontiercrown.com/mcp"]
}
}
}{
"mcpServers": {
"nostr-signer": {
"url": "https://signer.frontiercrown.com/mcp"
}
}
}{
"servers": {
"nostr-signer": {
"type": "http",
"url": "https://signer.frontiercrown.com/mcp"
}
}
}{
"context_servers": {
"nostr-signer": {
"url": "https://signer.frontiercrown.com/mcp"
}
}
}{
"mcpServers": {
"nostr-signer": {
"serverUrl": "https://signer.frontiercrown.com/mcp"
}
}
}{
"mcpServers": {
"nostr-signer": {
"url": "https://signer.frontiercrown.com/mcp"
}
}
}name: Nostr Signer
version: 0.0.1
schema: v1
mcpServers:
- name: Nostr Signer
type: streamable-http
url: https://signer.frontiercrown.com/mcp{
"mcpServers": {
"nostr-signer": {
"httpUrl": "https://signer.frontiercrown.com/mcp"
}
}
}{
"mcpServers": {
"nostr-signer": {
"type": "http",
"url": "https://signer.frontiercrown.com/mcp"
}
}
}{
"mcpServers": {
"nostr-signer": {
"url": "https://signer.frontiercrown.com/mcp"
}
}
}goose://extension?url=https%3A%2F%2Fsigner.frontiercrown.com%2Fmcp&type=streamable_http&id=nostr-signer&name=Nostr%20Signer
It answered our last check on 24 October 2026 in 415 ms. Over 6 checks since 12 September 2026 it answered 6. Status here comes from Neuronto's own probes, not from the publisher.
Yes. It is published by frontiercrown.com and served from signer.frontiercrown.com, the vendor's own domain: https://signer.frontiercrown.com/mcp.
17, as returned by the server's own tools/list on 23 September 2026: approve_grynvault_browser_handoff, begin_nostrconnect_pairing, connect_bunker, create_grynvault_nip05_invoice, create_grynvault_supporter_invoice, disconnect_signer, get_grynvault_account_dashboard, get_public_key, and 9 more.
It answered our last check on 24 October 2026 in 415 ms. Over 6 checks since 12 September 2026 it answered 6.
Put the server under mcpServers in ~/.cursor/mcp.json with the URL https://signer.frontiercrown.com/mcp. The exact JSON is above, with the same setup for Claude Code, Claude Desktop, VS Code, Windsurf, Zed, Gemini CLI and the rest.
It listed its tools to an anonymous client, so reading the tool list needs no key. Individual tools can still ask for credentials in their own inputs.
Publisher: com.frontiercrown.signer. Endpoint host: signer.frontiercrown.com. ARD identifier: urn:air:com.frontiercrown.signer:mcp:nostr-signer.
First indexed 11 September 2026. The tools are exactly what the server returned; nothing on this page
is inferred from its name. Ranking in Neuronto search is never for sale.