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x402 Stacks Sponsor Relay bronze

x402-relay.aibtc.com

“Gasless transaction relay and x402 V2 spec-compliant facilitator for AI agents on the Stacks blockchain. Accepts pre-signed sponsored transactions, covers the network fee, verifies payment parameters locally, and broadcasts directly to the Stacks network. Implements x402 V2 facilitator API (POST /settle, POST /verify, GET /supported) for use with standard x402 client libraries. Supports STX, sBTC, and USDCx tokens. API keys provisioned for free via BTC or STX signature.

a2a https://x402-relay.aibtc.com talk to it https://x402-relay.aibtc.com/.well-known/agent.json its card
Checked 5d ago pushNotifications, queueCancellation, queueVisibility, stateTransitionHistory, streaming, x402Facilitator, x402FacilitatorSpec, x402FacilitatorSpecUrl

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Verified by agenttru.st

Everything here is a check agenttru.st performed itself. Assurance, protocol, hosting and freshness are in the card above and are not repeated.

Certificate
Issued by Google Trust Services domain-validated
Valid until 4 Dec 2026.
Control of the hostname was checked; nothing about who operates it.
DANE / TLSA
Not verified (TLSA query returned RCodeNameError)
Discovery
Well-known document
First seen
9 Sep 2026
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Assurance
bronze Bronze — agent card fetched over HTTPS with a valid certificate
Protocols
A2A verified by handshake or card fetch, not merely advertised
Hosted in
? Unknown · Cloudflare, Inc. (AS13335)
The address did not geolocate — usually anycast hosting, where one address answers from many places at once.
Last checked
5d ago

What this agent says it can do

Declared in the agent's own card. agenttru.st has not tested whether it completes any of these tasks — the operator of x402-relay.aibtc.com controls every word below.

Relay Sponsored Transaction

Submit a pre-signed Stacks sponsored transaction for native settlement. The relay verifies payment params locally, pays the network fee, and broadcasts directly. Accepts STX, sBTC, and USDCx token transfers. No API key required. POST /relay with { transaction, settle: { expectedRecipient, minAmount, tokenType } }. Returns { txid, settlement, sponsoredTx, receiptId }. settlement.status is 'confirmed' (immediate) or 'pending' (60s timeout — safe to poll /verify/:receiptId). Idempotent: same tx hex returns cached result within 5 minutes.

gaslesssponsoredstacksx402settlement
Examples it gives
  • Relay a sponsored STX transfer without paying fees
  • Submit a gasless sBTC transaction via x402
  • Settle an x402 payment with the sponsor relay

Sponsor and Broadcast Transaction

Sponsor a pre-signed Stacks transaction and broadcast it directly to the network. No facilitator settlement — useful for non-payment transactions. Requires API key (Bearer token). POST /sponsor with { transaction }. Returns { txid, fee }. Optional SIP-018 auth via auth field.

gaslesssponsoredbroadcaststacks
Examples it gives
  • Broadcast a sponsored transaction directly
  • Sponsor a contract call without holding STX
  • Broadcast a gasless ERC-8004 identity registration

Provision API Key

Get a free-tier API key for POST /sponsor by signing a known message with your Bitcoin key. Supports all address types: P2PKH (1...) and P2SH (3...) use BIP-137; native SegWit (bc1q...) and Taproot (bc1p...) use BIP-322. POST /keys/provision with { btcAddress, signature, message }. Self-service path: message = 'Bitcoin will be the currency of AIs | <ISO-timestamp>'. Also available via Stacks signature: POST /keys/provision-stx. Returns apiKey (store securely — shown once).

api-keyprovisioningbitcoinstacksauthentication
Examples it gives
  • Get an API key using my Bitcoin signature
  • Provision a relay key for sponsored transactions
  • Get a free key by signing with my Stacks wallet

Verify Payment Receipt

Verify a payment receipt created by a successful POST /relay call. GET /verify/:receiptId returns status, sender, settlement details, and accessCount. Receipts are valid for 30 days.

receiptverificationpayment
Examples it gives
  • Check if a receipt is still valid
  • Verify a payment receipt from a relay transaction

Access Receipt-Gated Resource

Use a payment receipt to access a gated resource or proxy a downstream request. POST /access with { receiptId, resource?, targetUrl? }. The resource field must match the resource in the original settle options. If targetUrl is provided (HTTPS only), the relay proxies the request.

accessreceiptproxyx402
Examples it gives
  • Access a protected endpoint using a relay receipt
  • Proxy a request to a downstream service using a payment receipt

Get Fee Estimates

Get clamped fee estimates for Stacks transactions. GET /fees returns estimates for token_transfer, contract_call, and smart_contract at low/medium/high priority. No authentication required. Values in microSTX.

feesestimationstacks
Examples it gives
  • What are the current STX transaction fees?
  • Get fee estimates before building a transaction

Service Health Check

Check relay health and cached sponsor readiness. GET /health is the thin service summary, while GET /status/sponsor is the canonical cached sponsor status surface. Use before sending transactions to verify the relay is operational.

healthmonitoringstatus
Examples it gives
  • Is the relay healthy?
  • Check relay status before submitting a transaction

Agent Queue Visibility and Cancellation

Inspect your own pending sponsored transaction queue and cancel entries without operator intervention. GET /queue/:senderAddress returns queued, dispatched, replaying, and replay_buffer entries across all sponsor wallets. DELETE /queue/:senderAddress/:walletIndex/:sponsorNonce cancels a specific entry: queued→deleted, dispatched→replaying (flushed in next alarm cycle), replaying→deleted, replay_buffer→deleted. Both endpoints require SIP-018 auth (action: 'queue-read' / 'queue-cancel') — recovered signer must match :senderAddress. See /topics/queue-management for details.

queuecancelnoncesip018auth
Examples it gives
  • Show me my pending sponsored transactions
  • Cancel a stuck queued transaction
  • Check if my transaction is still in the relay queue

x402 V2 Facilitator

Spec-compliant x402 V2 facilitator (coinbase/x402 spec section 7). POST /settle — verifies payment params locally and broadcasts the transaction; auto-sponsors transactions with empty sponsor slots (fee=0 / all-zeros signer); returns { success, transaction, network, payer }. POST /verify — local validation only, no broadcast; returns { isValid, invalidReason?, payer? }. GET /supported — returns supported payment kinds (x402Version: 2, scheme: 'exact', CAIP-2 network). CAIP-2 networks: 'stacks:1' (mainnet), 'stacks:2147483648' (testnet). Assets: 'STX', 'sBTC', or CAIP-19 contract address. Returns HTTP 200 for successful settle/verify, HTTP 400 for malformed schema, and HTTP 409 Conflict when a payment-identifier collision is detected. Idempotent: same tx hex returns cached result within 5 minutes. Supports 'payment-identifier' extension: include a stable pay_<uuid> in paymentPayload.extensions for idempotency across tx rebuilds. See /topics/x402-v2-facilitator for payment-identifier details.

x402facilitatorsettlementstackscaip2
Examples it gives
  • Settle an x402 V2 payment on Stacks
  • Verify an x402 payment before broadcasting
  • Check supported payment kinds for this facilitator
  • Use this relay as an x402 V2 facilitator in my client

Agent Payment Guide

Payment guide for agents making x402 payments across aibtc services. Covers mental model (you sign, relay pays fee), per-service flows (inbox, news, MCP tools, skills), settlement status interpretation (confirmed/pending/failed), common errors, and network constants. GET /topics/agent-payments for condensed plaintext. Full guide: https://github.com/aibtcdev/x402-sponsor-relay/blob/main/docs/agent-payment-guide.md

x402paymentguideerrorssettlementstacks
Examples it gives
  • How do I make an x402 payment on Stacks?
  • What does CLIENT_BAD_NONCE mean and how do I fix it?
  • What is the difference between pending and confirmed settlement?
  • Which endpoint do I use to pay for aibtc.com inbox messages?

Technical agent card

Copied from the agent's card. The operator controls these values; agenttru.st has not verified them.

Provider
AIBTC Working Group — what this agent says about itself; other agents claiming the same provider are not thereby related
Protocol
a2a
Version
1.33.2
Card completeness
a2a.proto v1.0 requires eight top-level fields. This card omits:
supportedInterfaces
Missing fields do not affect listing — they describe how much the operator has published, not whether the agent was verified.
View all card details
Capabilities
pushNotifications queueCancellation queueVisibility stateTransitionHistory streaming x402Facilitator x402FacilitatorSpec x402FacilitatorSpecUrl
Agent card
https://x402-relay.aibtc.com/.well-known/agent.json

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