X402 Defillama

An x402 pay-per-call proxy in front of DefiLlama's agent MCP. An AI agent with a funded Base wallet uses DeFi data with no account, no subscription, no browser login — it pays USDC per tool call. Proxies 10 of DefiLlama's 23 MCP tools as a proof-of-concept.

Verified end-to-end on Base mainnet — real USDC settlement, on-chain.

Problem

DefiLlama runs a live 23-tool agent MCP (mcp.defillama.com/mcp). Today an agent can only use it with a DefiLlama account + active API subscription + browser login. An autonomous agent with a wallet but no account can't onboard. x402 (HTTP 402 + EIP-3009 USDC settlement) fixes exactly this: pay-per-call, no account. This repo proves the flow, and proposes it as an alternative auth to the existing API-key/credit rail — dual-auth, not a replacement.

Demo

The recording is a deterministic replay of a real Base-mainnet run (demo/demo.tape, regenerate with vhs demo.tape). The settlement it shows is a real on-chain transaction — see below.

Verify it yourself

Three independent ways to check this is real, not a mock:

1. On-chain proof. The settlement tx is on Base mainnet: 0xe58ae46d…abe7. status: success · USDC transfer payer → payTo, 0.001 USDC · gas paid by the facilitator (the payer's ETH is untouched — EIP-3009 is gasless for the payer). from / to / amount / status match the demo exactly.

2. Run it live against your own wallet. The video is a replay; here's the live path:

   git clone <repo> && cd x402-defillama-mcp && npm i
   cp .env.example .env
   npm run wallets:gen                 # generates burners; or paste your own
   # set PAY_TO_ADDRESS = your treasury, CLIENT_PRIVATE_KEY = your funded burner in .env
   # fund the client with a little USDC on Base (mainnet) or Base Sepolia (testnet)
   npm run dev                         # start the proxy
   npm run demo:script                 # agent pays per call → gets data → prints the settlement tx
   

   Testnet (Base Sepolia, NETWORK=base-sepolia, public facilitator, no keys) proves the identical mechanism with zero mainnet spend.

3. Real data. The figures returned are live DefiLlama data — e.g. Binance CEX ~$137.7B TVL — independently checkable on defillama.com. The proxy is a pass-through to DefiLlama's REST API, not a mock.

Architecture

flowchart LR
  A["AI agent<br/>(MCP client + Base wallet)"] -- "MCP tools/call" --> P["x402-defillama-mcp<br/>/mcp"]
  P -- "rail A · no key" --> X["402 + accepts[] → agent signs EIP-3009<br/>→ facilitator verifies + settles USDC on Base"]
  X -- "settled" --> P
  P -- "rail B · DefiLlama API-key header" --> S["skip 402 → serve via pro backend<br/>(existing subscription rail)"]
  P -- "resolves tool" --> D["DefiLlama REST<br/>api.llama.fi | pro-api.llama.fi/{KEY}"]

• Rail A (x402 pay-per-call): built on Coinbase's @x402/mcp (createPaymentWrapper on the MCP SDK). No payment → in-protocol 402 with an accepts[] (scheme exact, network, USDC, payTo, amount = the tool's price). The agent signs EIP-3009 transferWithAuthorization; the facilitator verifies + settles on-chain, then the tool runs. Facilitator = public facilitator on testnet (no keys); Coinbase CDP facilitator on mainnet.
• Rail B (dual-auth): a request carrying a DefiLlama API-key header skips the 402 and serves via the pro backend with that key. One server, two rails.
• Data-driven registry: each tool is one declarative row (name → endpoint → price → params); adding a tool = adding a row. The remaining 13 of DefiLlama's 23 tools drop in as rows (some need the Pro backend).
• Discovery: /.well-known/x402 (advertised networks) + /catalog (tools, prices, params).
• Price-sanity guard: the server refuses to start if any per-call price exceeds a ceiling (default $0.05) — protects against a decimals/units bug.

Run (2-minute quickstart)

npm i
cp .env.example .env
npm run wallets:gen        # fresh burners; funds/keys stay in .env (gitignored)
npm run dev                # proxy on http://localhost:4021  (POST /mcp)

No-spend checks: npm run backend:check (data layer), npm run smoke (MCP + the 402 gate), npm run dualauth-check (API-key rail skips the 402).

Config (.env): NETWORK (base-sepolia|base) · PAY_TO_ADDRESS · FACILITATOR (public|cdp) · DATA_BACKEND (free|pro) · PRICE_MODE (tiered|flat) · ALLOW_APIKEY_PASSTHROUGH · SESSION_TOKEN_MODE.

Production mapping

This is a PoC of a feature that would live in DefiLlama's own stack, not a data reseller:

• payTo = DefiLlama's treasury. In the demo it's a burner; in production the settlement USDC lands in your wallet.
• Backend is a one-env swap. The demo runs on the free public API to stay costless; in production DATA_BACKEND=pro points at your own gated Pro data over the identical path (pro-api.llama.fi/{KEY}/…). The x402 payment layer is byte-identical either way.
• Dual-auth = additive. x402 is an alternative auth to the API-key/credit flow, so existing keys keep working while agents onboard without a subscription. Nothing is removed.

Design decisions / FAQ

• Why a demo, not a PR? DefiLlama's MCP server and Pro-API billing are closed-source — there's no public file to patch. The credible move is a working proxy + the dual-auth recommendation.
• Doesn't this resell DefiLlama's data? No. It's a PoC of DefiLlama's own future feature; in production it fronts their gated data and the settlement goes to their treasury. The open free API stays open.
• Pay-per-call vs session tokens. Per-call is the demo (clearest: pay each call, no subscription). x402 V2 reusable session tokens (amortize per-call overhead) are scaffolded behind SESSION_TOKEN_MODE, default off.
• Multi-chain / CCTP. On mainnet the accepts[] can advertise Base + other chains so an agent pays where its treasury sits. Consolidating multi-chain revenue into one treasury is where CCTP would slot in as an optional sweep — noted, not built (Base-only needs none).

Extensions

Payments are rail-agnostic (src/payments/provider.ts) — a second rail drops in behind the same interface. src/payments/mpp.ts (Machine Payments Protocol — Stripe + Tempo's open, IETF-proposed agent-payment standard) is stubbed for now to keep this PoC's single thesis (x402 on the MCP) focused — not for any technical barrier. MPP is open (Apache-2.0/MIT, implementable via the mppx SDK; only Stripe's optional fiat/card path is gated, not the crypto rail) and a planned fast-follow — adding it makes the MCP monetizable on both leading agent-payment rails. Peers are already split across the two: CoinGecko shipped x402, Dune Analytics is on MPP. ACP slots in the same way.

Provenance

x402 API verified against Coinbase's coinbase/x402 examples; @x402/mcp / @x402/core / @x402/evm on the MCP SDK; CDP facilitator via @coinbase/x402. DefiLlama endpoints are live public API. DefiLlama already tracks x402 as a category (dimension-adapters#6181, merged).