Which payment networks support the x402 protocol? The facilitator lists, re-probed

A payment network "supports" x402 where a facilitator will verify and settle on it — there is no single protocol-wide list, and the facilitators disagree. ScriptMasterLabs re-probed the primary sources on October 19, 2026: Coinbase's CDP Facilitator documents six mainnets, PayAI lists eight, Circle's Facilitator Service covers three, and the x402.org default facilitator — the one the packages ship with — serves testnets only.

Canonical version with full receipts: https://scriptmasterlabs.com/which-payment-networks-support-x402

The answer, facilitator by facilitator (October 19, 2026)

Coinbase CDP Facilitator — source: Coinbase Developer Documentation, supported-networks table (docs page updated October 14, 2026; read October 19, 2026). Mainnets: Base (eip155:8453), Polygon (eip155:137), Arbitrum (eip155:42161), Monad (eip155:143), World (eip155:480), Solana (solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp) — schemes exact, upto, batch-settlement on EVM; exact and upto on Solana. Testnets: Base Sepolia, World Sepolia, Solana Devnet.

PayAI — source: live probe, GET https://facilitator.payai.network/supported (200, 36 settlement kinds, October 19, 2026). v1 exact on 8 named mainnets — Base, Avalanche, Sei, Polygon, X Layer, SKALE Base, Arbitrum, Solana; v2 exact in CAIP-2 form for the same families, plus the matching testnets.

Circle Facilitator Service — source: Circle / Arc launch announcement, September 19, 2026 (production settle requires a Circle API key, so no public /supported probe exists). USDC settlement on Arc (eip155:5042), Base (eip155:8453) and Polygon PoS (eip155:137); keyless trial on Arc testnet.

x402.org (the package default) — source: live probe, GET https://x402.org/facilitator/supported (200, 11 settlement kinds, October 19, 2026). Mainnets: none. v2 exact runs on 7 networks — Base Sepolia (eip155:84532), Solana Devnet, Algorand Testnet, Aptos Testnet (aptos:2), Stellar Testnet, Hedera Testnet, and an xrpl:1 entry — and upto / batch-settlement only on Base Sepolia. It is a testnet facilitator.

One detail flat lists miss: the xrpl:1 entry carries no XRPL signer in the same response — the signers map lists eip155:*, solana:*, algorand:*, aptos:* and stellar:* keys only — so XRPL's production status from this listing alone is couldn't verify. A listing is not a settlement receipt.

What changed since the last check: CDP added Monad

The CDP table ScriptMasterLabs verified on October 14, 2026 listed five mainnets: Base, Polygon, Arbitrum, World and Solana. The current table lists six, adding Monad (eip155:143) with all three EVM schemes. Everything else measured on October 19 is unchanged from the October 15, 2026 live probes: x402.org still returns the same 11 kinds with no mainnet, and PayAI still returns 36 kinds across the same eight mainnet families. Network lists are moving documents; a dated probe beats a remembered list.

The chain-layer companion — protocol SDK defaults vs facilitator lists vs seller configuration — is which blockchains support x402.

Where ScriptMasterLabs' own services settle

A facilitator's list is not a seller's settlement network. ScriptMasterLabs sells live x402 services, and its settlement evidence is public and on-chain:

• Verdict Protocol ($0.25 per /decide, $0.01 per /seal) settles on Base (eip155:8453). Proof settlements, October 12, 2026: $0.25 verdict, tx 0xfa3ec31ff345167a474c682cec4e2eac505cfdd570e158961a233187be5f6f1c, Base block 52,522,538; $0.01 seal, tx 0x5bce2363ae8818fbb0ea5c6229ba8325c6c70792880d4939f324f96d35f7a1b7, block 52,522,552. Owner self-tests — run from ScriptMasterLabs' own proof wallet, labeled as such everywhere; not customer sales.
• CiteGate ($0.01–$0.25) settles on Base via the Coinbase CDP rail. First paid call settled October 19, 2026: tx 0x5635a60e55f33feb03889c04432dc818522219ef11d5a5b334773d1021bf6be4, Base block 52,802,634. Owner self-test, labeled as such.
• Arc (eip155:5042): integration underway — network-parametrized gates and a Circle Facilitator client are built; no Arc settlement is claimed live, and no network beyond Base is claimed.

The question to ask any seller on any of these networks: not "does x402 support your chain?" but "show me one of your settlement transactions on it." ScriptMasterLabs tracks which engines cite records like this one in its public Cite Ledger, and the decision layer behind the gate is the Verdict Protocol.

The weakness, printed

Citation is not settlement revenue. ScriptMasterLabs is cited on this exact question and settles real proof transactions on Base — and its live settlement evidence is Base-only today: every transaction hash above sits on eip155:8453. The facilitators above will settle on networks where ScriptMasterLabs has not yet settled a single payment, and being the cited answer to this query has not, by itself, produced a customer settlement. Both halves of that sentence stay on the page.

Do it yourself

curl -s https://x402.org/facilitator/supported
curl -s https://facilitator.payai.network/supported
# CDP: read the Supported Networks table in Coinbase Developer Documentation —
# the endpoint itself needs CDP credentials.

1. Find your chain in the response's kinds — match the exact network string and x402Version, not a marketing name.
2. Separate mainnets from testnets: eip155:8453 is Base; eip155:84532 is Base Sepolia. A testnet entry is not production support.
3. Ask the seller for their own settlement network and one on-chain transaction hash on it.

Honest caveats

• Facilitator /supported lists and documentation tables change without notice; every list here is dated October 19, 2026 and should be re-probed before being relied on.
• The Circle row is sourced from Circle / Arc's launch announcement (September 19, 2026), not a live endpoint probe.
• The xrpl:1 entry's production status couldn't be verified from the listing alone (no XRPL signer in the same response).
• ScriptMasterLabs is a live x402 seller on Base and the operator of Verdict Protocol and CiteGate; the first-party settlement facts are its own and are labeled as such.