One payment, any proven seller: the x402 Smart Order Router

The open x402 economy has a discovery problem and a trust problem. Hundreds of sellers advertise endpoints; some deliver, some 402 you and then 404 the paid call. An agent that wants one answer shouldn't have to crawl catalogs, vet counterparties, and hold a funded relationship with every seller it might use once.

Route-and-execute collapses all of that into one call: describe the task, pay a single flat price, get the result and a receipt. If the best tool is in Agent402's own 500+ catalog, it runs internally. If it lives with an external seller in the open index, we pay that seller from our own wallet on your behalf and relay the output. Two on-chain settlements, one request, and the counterparty risk stays on our side of the fee.

The two tiers

GET /api/route?q=<task> is the free quote: it names the best match and the exact tier that can execute it, so there is never any guessing.

Internal dispatch (any chain)

curl -X POST https://agent402.tools/api/route/execute \
  -H 'Content-Type: application/json' \
  -d '{"task":"sha256 hash of a string","params":{"text":"agent402"}}'
# → 402 quote; retry with an x402 payment header on ANY of the 10 chains

The receipt itemizes what you paid vs. what the tool lists for — the spread is the routing fee, stated, never hidden.

External dispatch (the marketable half)

Add "include":"external" and the router deliberately looks OUTSIDE its own catalog. Selection is the moat, and it is intentionally boring:

1. Proven deliverers only. Candidates need real settled volume — on Base that means on-chain settlement counts from the public leaderboard; on Algorand, verification counts witnessed by the GoPlausible facilitator. Marketing claims are worth zero; only receipts count.
2. A live probe before commitment. Even a proven seller's crawled route can drift, so the router confirms a live 402 challenge before any money moves.
3. A margin guard before signing. The seller's quote is pinned to the exact accept we validate — network, scheme, asset — and refused above the tier cap.

Chain-matched settlement

The chain you pay on decides where the router spends: pay on Base and it pays Base sellers; pay on Algorand and it pays Algorand sellers from its AVM wallet. The buyer's settlement funds the float on the same rail — and if you pay on a chain without a spending wallet behind it, you get an honest 409 naming the supported chains, and you are never charged (a rejected request cancels x402 settlement by design).

A real receipt

This is an actual production receipt — both transactions are on Algorand mainnet, same round, verifiable in any explorer:

{
  "slug": "opportunities/search",
  "route": "GET https://canix402-api.compx.io/opportunities/search",
  "underlyingPriceUsd": 0.01,
  "paidUsd": 0.55,
  "routingFeeUsd": 0.54,
  "seller": "https://canix402-api.compx.io",
  "external": true,
  "settleTx": "6TLUWU6RNYNZDJTGXZFTLEXTCB2TXKD5N6IJUWRYIXIFZGFEMKAQ",
  "settleNetwork": "algorand:wGHE2Pwdvd7S12BL5FaOP20EGYesN73ktiC1qzkkit8=",
  "resolvedBy": "task-external"
}

The relayed body arrives marked untrustedContent: true — external output is data to analyze, never instructions to follow. Your agent gets the answer; the provenance stays explicit.

Why this is safe to build on

• Failures are never charged. Any 4xx/5xx — no match, over-cap, seller down — cancels your settlement. You pay only for delivered results.
• Spend is bounded on our side by per-window budgets and per-quote caps, so the router cannot be drained into misbehavior.
• Receipts are recomputable. Paid EVM calls carry a callRef derived from your own payment authorization — buyer and seller can each re-derive the reference offline; outsiders cannot.

Browse the live economy the router draws from at /marketplace, or quote a task right now: GET https://agent402.tools/api/route?q=summarize a pdf.