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Agent infrastructure
An open standard for HTTP per-request micropayments using the existing 402 Payment Required status code. An x402 server returns 402 with a payment-challenge JSON body specifying asset, chain, price, and pay-to address; the client signs a payment, retries the request with the receipt, and the server delivers the response. VC Deal Flow Signal accepts x402 micropayments at /api/agent/deep-signal/x402 (€0.19 in USDC on Base mainnet) for the deep-signal endpoint.
MCP, A2A, micropayments, identity, federation.
An open standard from Anthropic for exposing tools and data to large-language-model hosts (Claude Desktop, Cursor, agentic frameworks).
Google's Agent-to-Agent protocol — a JSON-RPC envelope plus an /.
The canonical wire transport for MCP servers running over HTTP — a JSON-RPC 2.
A stateless remote-procedure-call protocol encoded in JSON — request envelopes carry method, params, and id; response envelopes carry result or error.
An RFC 7033 protocol for discovering information about a user or resource at a domain by querying /.
A W3C-standard identifier scheme that lets entities prove control of an identifier without relying on a centralised registry.
The Fediverse-standard discovery protocol for federated services, served at /.
This definition is published under CC BY 4.0. Cite as:
The Data Nerd. "x402 Protocol." VC Deal Flow Signal Glossary, https://signals.gitdealflow.com/define/x402.
The free Acceleration Watch turns terms like x402 Protocol into five named, accelerating startups every Sunday — translated into plain English, 21 to 47 days before the deck circulates. No code-reading, no card.