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What is L402?

L402 revives HTTP status 402 "Payment Required". A server answers a request with a 402, a Lightning invoice and a macaroon (a scoped token). The agent pays the invoice, then retries with the macaroon plus the payment preimage as proof. No accounts or API keys. Spec: lightninglabs/L402.

What is Nostr Wallet Connect?

NWC lets an app or agent control a remote Lightning wallet over Nostr relays, with permissions and budgets the owner sets. It is a common way to give an agent a spending wallet. See nwc.dev.

What is Cashu?

Cashu is a Chaumian ecash protocol backed by Bitcoin via Lightning mints. Tokens are bearer and private, which suits tiny per-request payments. See cashu.space.

L402 vs x402 vs MPP

	L402	x402	MPP
Rail	Bitcoin Lightning	Stablecoins on chains like Base, Solana	Stripe / Tempo
Auth	Macaroon + preimage	Signed payment payload	Stripe-managed

Directory of endpoints across all three: 402 Index.