v402 — Verus-native pay-per-request for AI-agent APIs

Charge AI agents per request; let agents pay autonomously — in Verus-native currencies. Same HTTP-402 handshake as Coinbase's x402, but the payment layer is Verus: VerusID identity, off-chain signatures for zero-latency auth, and a prepaid balance for near-zero per-request cost. No gas per call, no API keys, no card on file — one signature per request, settled against an on-chain-funded balance.

Beta on testnet. Spec v402/0.1 is normative and frozen; all 14 reference packages are on npm (OIDC trusted publishing, SLSA provenance); the stack is verified end-to-end against VRSCTEST including real on-chain deposits. Mainnet is a config change away — not yet blessed for production.

60-second demo: Claude pays for an API

Add @chainvue/v402-mcp to Claude Desktop or Claude Code:

{ "mcpServers": { "v402": {
  "command": "npx",
  "args": ["-y", "@chainvue/v402-mcp"],
  "env": {
    "V402_MCP_FACILITATOR": "https://facilitator.example.com",
    "V402_MCP_IDENTITY": "myagent@",
    "VERUS_SIGNING_KEY": "<WIF>",
    "V402_MCP_IDENTITY_ADDRESS": "<i-address>",
    "V402_MCP_SYSTEM_ID": "<chain i-address>",
    "V402_MCP_MAX_PER_REQUEST": "0.01",
    "V402_MCP_MAX_TOTAL": "1"
  }
} } }

Ask Claude to fetch a priced endpoint — it discovers prices, pays within your caps, and refuses the rest. Limits are checked against the 402 challenge before anything is signed:

paid_fetch /api/status → 200 | paid 0.0001 VRSCTEST | sessionSpent 0.0001
cap check /api/report (0.01 > cap 0.005): REFUSED

Pick your path

Charge for your API — a NestJS decorator:

@Get("api/report") @V402Payment("0.01")
report() { … }

…or drop the reverse proxy in front of any existing origin (any language, no code changes): a rules file prices your routes, docker compose -f docker-compose.proxy.yml up does the rest.

Pay as a client — @chainvue/v402-client-fetch:

const paidFetch = wrapFetchWithPayment(fetch, { payer: "myagent@", signer });
await paidFetch("https://api.example.com/api/report"); // 402 handled transparently

Parallel-safe, self-healing on price changes. Or use the MCP server above — no code.

Implement the standard — spec/0.1/ is normative (CC-BY-4.0, RFC 2119). Prove any implementation, in any language, against the vectors:

npx v402-conformance --strict -- ./my-implementation

Start with the implementer guide; the facilitator contract is machine-readable as OpenAPI 3.1.

Packages

All published as @chainvue/* under Apache-2.0.

Package	What it is
v402-protocol	canonical payload, headers, wire schemas — dependency-light core
v402-signer-verus	Verus crypto: address + VerusID (N-of-M) signing and offline verify
v402-verifier	scheme verifier (RPC or offline mode), facilitator HTTP client
v402-verus-rpc	minimal, v402-scoped Verus JSON-RPC client
v402-storage / -sqlite	balance/ledger interface + SQLite implementation
v402-deposit-watcher	on-chain deposit detection, reorg handling, attribution
v402-facilitator	standalone payment daemon: verify/reserve/commit/rollback API
v402-nestjs	NestJS guard + interceptor + discovery controller
v402-proxy	reverse proxy: payment guard in front of any origin
v402-client-fetch	paying fetch wrapper + full client (balance, topup, discovery)
v402-mcp	MCP server: agents pay mid-conversation, with spending caps
v402-test-vectors	the normative vectors as an npm package
v402-conformance-suite	conformance runner + cross-language CLI

Develop

Node ≥ 22, pnpm ≥ 10.

pnpm install
pnpm build && pnpm typecheck && pnpm lint && pnpm test

docker-compose.yml boots the facilitator + demo-server pair; the contributor path uses simulated deposits and needs no Verus node. Node-gated integration tests skip cleanly without VERUS_RPC_URL. Integration guides: docs/integration/.

Licensing

Code (packages/, apps/) is Apache-2.0 (LICENSE-CODE) — an explicit patent grant, relevant in the payments/crypto space. The protocol spec (spec/) is CC-BY-4.0 (LICENSE-SPEC) — reproduce, translate, and build on it with attribution. Permanently forkable, no vendor lock-in. Stewarded by chainvue (Robert Lech) during v0.x; see spec/governance.md and NOTICE.