402-mcp

Nostr: npub1mgvlrnf5hm9yf0n5mf9nqmvarhvxkc6remu5ec3vf8r0txqkuk7su0e7q2

L402 + x402 client MCP that gives AI agents economic agency. Discover, pay for, and consume any payment-gated API — no human registration, no API keys, no middlemen.

• Discover paid APIs on Nostr — no URLs needed upfront
• Auto-pay with Lightning (NWC), Cashu ecash, or human QR fallback
• Credentials cached and encrypted at rest (AES-256-GCM)
• Works with any L402 server — toll-booth, Aperture, or any future implementation

Quick start

1. Install

npx 402-mcp

2. Connect to Claude Code

claude mcp add 402-mcp -- npx 402-mcp

3. Try it

Ask Claude: "Search for paid joke APIs using l402-search" — no wallet needed, just discovery.

Ready to make paid calls? See the full quickstart guide to set up a wallet and watch your agent pay for its first API call.

How it works

graph LR
    A["1. l402-config()"] --> B["2. l402-discover(url)"]
    B --> C["3. Agent reasons<br/>about pricing"]
    C --> D["4. l402-buy-credits()<br/>or l402-fetch()"]
    D --> E["5. l402-fetch(url)<br/>with credentials"]
    E --> F["6. Data returned<br/>+ balance cached"]

Loading

Example session:

Agent: "I need routing data from routing.trotters.cc"

1. l402-config()
   -> nwcConfigured: true, maxAutoPaySats: 1000

2. l402-discover("https://routing.trotters.cc/api/route")
   -> 10 sats/request, toll-booth detected, tiers available

3. Agent reasons: "I need ~20 requests. The 500-sat tier
   gives 555 credits. Better value."

4. l402-buy-credits(url, amountSats=500)
   -> Paid 500 sats, received 555 credits

5. l402-fetch("https://routing.trotters.cc/api/route?from=...&to=...")
   -> 200 OK, route data, 545 credits remaining

For detailed architecture and payment flow diagrams, see docs/architecture.md.

Configuration

Variable	Default	Description
NWC_URI	-	Nostr Wallet Connect URI for autonomous Lightning payments
CASHU_TOKENS	-	Path to Cashu token store file
MAX_AUTO_PAY_SATS	1000	Safety cap; payments above this require human confirmation
CREDENTIAL_STORE	~/.402-mcp/credentials.json	Persistent macaroon/credential storage
TRANSPORT	stdio	Transport mode: stdio or http
PORT	3402	HTTP server port (when TRANSPORT=http)
TRANSPORT_PREFERENCE	onion,hns,https,http	Preferred transport order for multi-URL services (comma-separated)
TOR_PROXY	-	SOCKS5 proxy for .onion addresses (e.g. socks5h://127.0.0.1:9050)
SOCKS_PROXY	-	Generic SOCKS5 proxy for all requests when set
HNS_GATEWAY_URL	-	HTTP gateway for Handshake (.hns) domains (e.g. https://hns.to)

Transport selection and fallback

When a kind 31402 event advertises multiple URLs (one per transport), 402-mcp selects the best one based on your configuration:

1. Preference first — if TRANSPORT_PREFERENCE=tor and a .onion URL is available, it is tried first.
2. Availability fallback — if the preferred transport is unreachable (proxy not configured, timeout), the client falls back to the next URL in the list.
3. Clearnet default — if no preference is set, clearnet URLs are tried before .onion or HNS entries.

Services can announce multiple endpoints for the same service (same pricing, same macaroon key) on different transports. This is purely for censorship resistance; you do not need to re-authenticate when switching transports. To reach Tor or HNS endpoints you must configure the corresponding proxy/gateway env vars above.

Tools

Core L402 (any server)

Tool	Description
l402-config	Introspect payment capabilities (wallets, limits, credential count)
l402-discover	Probe an endpoint to discover pricing without paying
l402-fetch	HTTP request with L402 support; auto-pays if within budget
l402-pay	Pay a specific invoice (NWC, Cashu, or human-in-the-loop)
l402-credentials	List stored credentials and cached balances
l402-balance	Check cached credit balance for a server
l402-search	Discover L402 services on Nostr relays (kind 31402 announcements)
l402-store-token	Store an L402 token obtained from a payment page

toll-booth extensions

Tool	Description
l402-buy-credits	Browse and purchase volume discount tiers
l402-redeem-cashu	Redeem Cashu tokens directly (avoids Lightning round-trip)

Payment methods

Three payment rails, tried in priority order:

1. NWC (Nostr Wallet Connect) — fully autonomous; pays from your connected wallet
2. Cashu — fully autonomous; melts ecash tokens to pay invoices
3. Human-in-the-loop — presents QR code, polls for settlement

The agent can override the method per-call, or you can configure only the methods you want.

l402-fetch handles four HTTP 402 challenge variants transparently:

Protocol	Challenge header	Payment
L402	WWW-Authenticate: L402	Lightning invoice via wallet stack
IETF Payment (draft-ryan-httpauth-payment-01)	WWW-Authenticate: Payment	Lightning invoice via wallet stack
xCashu (NUT-18)	X-Cashu: creqA…	Ecash token sent directly (requires Cashu wallet)
x402	X-Payment-Required: x402	On-chain EVM transfer; surfaced to human with EIP-681 deeplink

Safety

MAX_AUTO_PAY_SATS caps any single autonomous payment. Above this limit, the agent must ask the human for approval. The agent can read this limit via l402-config and factor it into purchasing decisions.

Privacy

402-mcp stores credentials locally on your machine only (~/.402-mcp/credentials.json, encrypted at rest). No data is sent to any third party. No accounts, no tracking, no analytics. Payments use Lightning or Cashu — pseudonymous by design.

Ecosystem

Browse live L402 services at 402.pub — the decentralised marketplace for payment-gated APIs.

Project	Role
toll-booth	Payment-rail agnostic HTTP 402 middleware
satgate	Pay-per-token AI inference proxy (built on toll-booth)
402-mcp	MCP client — AI agents discover, pay, and consume L402 + x402 APIs
402-announce	Publish L402 services on Nostr for decentralised discovery

402-mcp is the payment-rail agnostic alternative to Lightning Labs' lightning-agent-tools and Coinbase's x402 — no Lightning node required, multiple wallets, encrypted credentials.

Full comparison

	402-mcp	Lightning Labs agent tools
Payment rails	NWC + Cashu + human fallback	Lightning only
Node required?	No — connects to any NWC wallet	Yes — runs LND
Server compatibility	Any L402 server	Aperture-focused
Spend safety	Per-payment cap + rolling 60s window	Per-call max-cost
Credential storage	Encrypted at rest (AES-256-GCM)	File permissions
Privacy	No PII, SSRF protection, error sanitisation	Standard

Use Lightning Labs' tools if you want agents that run their own Lightning node. Use 402-mcp if you want agents that pay from any wallet without infrastructure.

See CONTRIBUTING.md for development setup and guidelines.

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Built by @forgesworn.

• Lightning tips: thedonkey@strike.me
• Nostr: npub1mgvlrnf5hm9yf0n5mf9nqmvarhvxkc6remu5ec3vf8r0txqkuk7su0e7q2

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Part of the ForgeSworn Toolkit

ForgeSworn builds open-source cryptographic identity, payments, and coordination tools for Nostr.

Library	What it does
nsec-tree	Deterministic sub-identity derivation
ring-sig	SAG/LSAG ring signatures on secp256k1
range-proof	Pedersen commitment range proofs
canary-kit	Coercion-resistant spoken verification
spoken-token	Human-speakable verification tokens
toll-booth	L402 payment middleware
geohash-kit	Geohash toolkit with polygon coverage
nostr-attestations	NIP-VA verifiable attestations
dominion	Epoch-based encrypted access control
nostr-veil	Privacy-preserving Web of Trust

Licence

MIT