Facilitator coverage

Introduction

When you offer a standard exact rail settled by a third-party facilitator, you need to know which facilitator settles exact on your chain — and ideally a keyless one, so neither you nor the buyer pays gas. PipRail ships that knowledge as plain data (no hosted registry, no backend) plus a live reader, so you can choose or verify a facilitator up front.

This is the honesty layer under the upcoming exact: true shorthand: it resolves a known keyless facilitator for your gate’s network from this map, or fails with a clear message when none is known.

Live-verified facilitators

The third-party x402 facilitators below were probed live (2026-06-14 → 2026-06-17) — each one’s GET /supported was read, and every row marked ✅ was then settled with a real mainnet exact payment through PipRail, where the buyer paid zero gas. “Keyless” means it settles with no API key, so the facilitator sponsors the network fee for the buyer and the merchant. You point a gate at any of them with exact: { settle: { facilitator: '<facilitator url>' } } — see the exact rail seller guide. On a facilitator-sponsored fee-payer rail the gate also bounds the fee a buyer can make the sponsor pay — see sponsor protection.

Facilitator	Keyless?	PipRail live-tested	Mainnet exact networks
PayAI	✅ keyless	✅ Base, Polygon, Arbitrum, Avalanche, Sei, Solana	Base, Solana, Avalanche, Polygon, Arbitrum, Sei +24
Ultravioleta DAO	✅ keyless	✅ Ethereum, Polygon, Arbitrum, Optimism, Unichain, HyperEVM, Base, Monad	HyperEVM, Base, Monad, Celo, Unichain, Optimism, Scroll, Ethereum, Arbitrum, Polygon, Avalanche, BNB + Solana, Stellar, Sui, Algorand, NEAR, XRPL (18 listed — but Celo/Scroll/Avalanche contract_call_failed; non-EVM advertise-only)
Dexter	✅ keyless	✅ Base, Polygon, Arbitrum, Optimism, Avalanche, BNB	Base, BNB, Solana, Polygon, Arbitrum, Optimism, Avalanche (BNB: FDUSD/USD1/U only; ~$0.003 dynamic floor — sub-floor payments rejected)
Corbits	✅ keyless	✅ Solana, Base, Polygon, Monad	Solana, Base, Polygon, Monad +38
Polygon Labs	✅ keyless	✅ Polygon	Polygon (the official Polygon facilitator)
GoPlausible	✅ keyless	✅ Algorand + Base	Algorand (the only keyless Algorand facilitator), Base, Solana
Pieverse	✅ keyless	✅ Monad + BNB	Monad, BNB, Base (BNB: FDUSD/USD1/U)
Cascade	✅ keyless	✅ Base	Base, Solana
Satoshi (bitcoinsapi)	✅ keyless	✅ Base	Base, Solana
OpenFacilitator	✅ keyless	✅ Solana	Base, Solana, Stacks
xpay	✅ zero-fee	✅ Base	Base
Daydreams	🔑 API key	—	Ethereum, Base, Solana
Questflow	🔑 API key	—	Base
Coinbase CDP	🔑 CDP auth	—	Base, Solana
Kora	self-host	—	Solana

Base URLs (pass to exact: { settle: { facilitator } }) — the keyless ones, live-proven: https://facilitator.payai.network · https://facilitator.corbits.dev · https://pay.openfacilitator.io · https://facilitator.xpay.sh · https://facilitator.ultravioletadao.xyz · https://x402.dexter.cash · https://x402.polygon.technology (Polygon) · https://facilitator.goplausible.xyz (Algorand) · https://facilitator.pieverse.io · https://facilitator.cascade.fyi · https://facilitator.bitcoinsapi.com.

A public /supported is NOT proof of keyless settlement

Daydreams and Questflow both expose a public GET /supported, but their /verify returns 401 — an API key is required — so they are not keyless for settlement. We mark a facilitator “keyless ✅” only after a real payment settled with no key. That’s exactly why PipRail’s KNOWN_FACILITATORS seed map (below) lists only the live-confirmed keyless ones.

Live settlement proofs (real mainnet, sub-cent amounts): PayAI Solana 4dL8jRKH… · OpenFacilitator Solana 5BabDtX… · Corbits Solana BCreYer… · xpay Base 0x2273d5… · Corbits Monad 0x7797be… · Ultravioleta HyperEVM 0x56af81…. The 2026-06-18 gasless-extension added 17 more live proofs across Ethereum, Polygon, Arbitrum, Optimism, Avalanche, Sei, and Unichain (e.g. UVD Ethereum 0x7fcc3c… · PayAI Polygon 0xb37630…) — the full per-pair tx hash lives in each KNOWN_FACILITATORS entry, and every one was re-verified on-chain to confirm a third-party (the facilitator) paid the gas, never the buyer or merchant.

You’re never locked to any of them — keep one, swap it, or run your own (self-settle / Kora). See keep PayAI, or swap it. PipRail depends on no facilitator.

KNOWN_FACILITATORS — the seed map

A Record<Caip2, KnownFacilitator[]> mapping a CAIP-2 network to the facilitators known to settle exact there. It is deliberately conservative — only endpoint-verified entries — and grows only after a live /supported read confirms a new pair.

import { KNOWN_FACILITATORS, knownFacilitatorsFor, firstKeylessFacilitator } from '@piprail/sdk'

knownFacilitatorsFor('eip155:8453') // Base — eight live-verified keyless facilitators (all settle eip3009)
// → [PayAI, xpay, Ultravioleta DAO, Dexter, Corbits, GoPlausible, Cascade, Satoshi]
//   (8 entries; each shaped { url, keyless: true, schemes: ['exact'], settles: ['eip3009'], note })

firstKeylessFacilitator('solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp', 'svm')?.url
// → 'https://facilitator.payai.network'  (first of PayAI · OpenFacilitator · Corbits)

firstKeylessFacilitator('eip155:999999') // unknown network
// → undefined

Each KnownFacilitator has a url (no trailing slash), a keyless boolean (true ⇒ no API key, the facilitator sponsors gas), the schemes it settles (today 'exact'), the exact transfer settles methods ('eip3009' | 'permit2' | 'svm' | 'algorand' | 'aptos' | 'near'), and an optional note.

Caution

What’s seeded, and what isn’t. The map carries only live-confirmed keyless entries — each settled a real mainnet payment with no key, buyer paid zero gas (see Live-verified facilitators):

• Base (eip155:8453) → PayAI + xpay + Ultravioleta DAO + Dexter + Corbits + GoPlausible + Cascade + Satoshi (eip3009) — eight keyless facilitators (UVD/Dexter/Corbits/GoPlausible 2026-06-17; Cascade/Satoshi 2026-06-18)
• Ethereum (eip155:1) → Ultravioleta DAO (eip3009) — live-settled 2026-06-18. UVD 100%-sponsors L1 gas with no floor; the keyless Ethereum option (Primev rejects PipRail’s exact as unsupported_scheme).
• Polygon (eip155:137) → PayAI + Polygon Labs + Corbits + Ultravioleta DAO + Dexter (eip3009) — live-settled 2026-06-18. Five keyless facilitators — the broadest coverage after Base.
• Arbitrum (eip155:42161) → PayAI + Ultravioleta DAO + Dexter (eip3009) (live-settled 2026-06-18)
• Optimism (eip155:10) → Dexter + Ultravioleta DAO (eip3009) (live-settled 2026-06-18)
• Avalanche (eip155:43114) → PayAI + Dexter (eip3009) (live-settled 2026-06-18)
• Sei (eip155:1329) → PayAI (eip3009) (live-settled 2026-06-18)
• Unichain (eip155:130) → Ultravioleta DAO (eip3009) (live-settled 2026-06-18)
• BNB (eip155:56) → Dexter + Pieverse (eip3009) — live-settled 2026-06-17 with FDUSD; U live-settled 2026-06-21 via Pieverse (buyer 0 BNB). BNB’s USDC/USDT are Binance-Peg (Permit2, not facilitator-settleable), so keyless BNB works only for the EIP-3009 tokens FDUSD/USD1/U, and Dexter enforces a ~$0.003 dynamic floor. This beats the BNB token-overlap wall — both Dexter and Pieverse accept U, and Pieverse settles FDUSD too, so BNB now has two keyless facilitators.
• Monad (eip155:143) → Corbits + Ultravioleta DAO + Pieverse (eip3009) (live-settled 2026-06-17)
• HyperEVM (eip155:999) → Ultravioleta DAO (eip3009) (live-settled 2026-06-17)
• Algorand (algorand:wGHE2Pwdvd7S12BL5FaOP20EGYesN73ktiC1qzkkit8=) → GoPlausible (algorand) — new, live-settled 2026-06-17. Atomic-group fee pooling: GoPlausible’s sponsor pools the whole group fee, so both the buyer AND the merchant pay 0 ALGO. The first non-EVM/non-Solana keyless chain.
• Solana → PayAI + OpenFacilitator + Corbits (svm)

So exact: true is zero-config gasless on 13 chains today — Ethereum, Polygon, Arbitrum, Optimism, Avalanche, Sei, Unichain, Base, BNB, HyperEVM, Monad, Solana, and Algorand (multiple keyless facilitators per chain = automatic failover). Celo and Scroll are NOT seeded — Ultravioleta DAO advertises them but its sponsor contract reverts there (contract_call_failed), proving again that a /supported listing isn’t settlement. Daydreams and Questflow are deliberately omitted — their /supported is public but /verify needs an API key. x402.org/facilitator is not seeded either — it’s a Base Sepolia testnet facilitator, not a mainnet rail. Aptos has no keyless x402 facilitator on mainnet yet — use self-settle for gasless Aptos (proven on mainnet). Sui’s ratified exact scheme is interactive (the buyer must round-trip to a gas station to fill in gas objects before signing), so it isn’t wired as a one-shot keyless rail here yet. On a network not in the map, pass an explicit exact: { settle: { facilitator } }.

Reading a facilitator’s live /supported

facilitatorCoverage(url) fetches a facilitator’s GET /supported and returns the (scheme, network) kinds it advertises. It is best-effort and never throws — a dead or changed endpoint resolves to [], mirroring the SDK’s other read-only methods.

import { facilitatorCoverage } from '@piprail/sdk'

await facilitatorCoverage('https://facilitator.payai.network')
// → [{ scheme: 'exact', network: 'eip155:8453' },
//    { scheme: 'exact', network: 'solana:5eykt4Us…', feePayer: 'Fee…' }]

Each kind also carries two optional fields when the facilitator advertises them: x402Version (the envelope version it reports per kind) and assetTransferMethod ('eip3009' | 'permit2') — so a reader can tell a v1 rail from a v2 rail, or a gasless EIP-3009 kind from a Permit2 one, straight from /supported. Both are omitted entirely when absent (never a undefined key), so a facilitator that reports neither parses exactly as before.

parseFacilitatorSupported(body) is the pure parser behind it (useful in tests or when you already hold the body):

import { parseFacilitatorSupported } from '@piprail/sdk'

parseFacilitatorSupported({ kinds: [{ scheme: 'exact', network: 'eip155:8453' }] })
// → [{ scheme: 'exact', network: 'eip155:8453' }]

parseFacilitatorSupported('garbage') // tolerant — never throws
// → []

Use these to verify a facilitator covers your CAIP-2 network before wiring a gate, or to generate a coverage table from live reads. See the exact rail seller guide for turning on the rail itself.