Supported chains

The 0xGasless facilitator currently supports three EVM networks plus Solana (mainnet and devnet). More are planned.

Mainnet

Avalanche C-Chain

Field	Value
Network slug	`avalanche`
Aliases	`avalanche-mainnet`, `avax`, `avax-mainnet`
Chain ID	`43114`
Facilitator URL	`https://x402.0xgasless.com`
Explorer	snowtrace.io
USDC (canonical / EIP-3009)	`0xB97EF9Ef8734C71904D8002F8b6Bc66Dd9c48a6E`
XSGD (StraitsX / EIP-3009)	`0xb2F85b7AB3c2b6f62DF06dE6aE7D09c010a5096E`
USDC.e (bridged)	`0xA7D7079b0FEaD91F3e65f86E8915Cb59c1a4C664`
USDT (canonical)	`0x9702230A8Ea53601f5cD2dc00fDBc13d4dF4A8c7`
USDT.e (bridged)	`0xc7198437980c041c805A1EDcbA50c1Ce5db95118`
ERC-8004 identity supported	Yes

USDC and XSGD are EIP-3009 native — signed authorizations settle directly against the token contract via transferWithAuthorization. No pre-approve needed.

USDT and the .e bridged tokens are not EIP-3009. They settle via the A402 fallback path, which is different from your code’s perspective: the payer must approve() the listed relayerContract once (an on-chain transaction — so this path isn’t fully gasless for the payer’s first use), and signs under the A402 relayer domain instead of the token’s domain. Read the per-token settlement mode from GET /tokens; prefer the EIP-3009 tokens (USDC, XSGD) when you can.

XSGD notes

XSGD is the Singapore-dollar stablecoin issued by StraitsX — 1 XSGD = 1 SGD (~US$0.77), 6 decimals.
EIP-712 signing domain: { name: "XSGD", version: "2" }. Unlike USDC, the XSGD contract exposes no on-chain DOMAIN_SEPARATOR()/version() getters, so you cannot discover this domain from the contract — read it from GET /tokens instead of probing.
The contract is pausable and has an issuer blacklist (standard for regulated stablecoins). If a transfer party is blacklisted or the token is paused, /settle returns the revert reason.
On the 0xGasless platform, spend caps are USD-denominated: XSGD amounts are converted with the live Chainlink SGD/USD feed, so a 10 XSGD payment counts as ≈ $7.75 against your caps — not $10.

Base

Field	Value
Network slug	`base`
Aliases	`base-mainnet`
Chain ID	`8453`
Facilitator URL	`https://x402.0xgasless.com`
Explorer	basescan.org
USDC (canonical)	`0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`
ERC-8004 identity supported	Not yet (planned)

Base only does the canonical EIP-3009 scheme.

ERC-8004 identity isn’t available on Base yet. Agents can still spend on Base; they just can’t have an on-chain identity NFT there.

Testnet

Avalanche Fuji

Field	Value
Network slug	`avalanche-fuji`
Aliases	`avalanche-testnet`, `fuji`, `avax-testnet`
Chain ID	`43113`
Facilitator URL	`https://x402.0xgasless.com` — same URL as mainnet
Explorer	testnet.snowtrace.io
USDC (canonical / EIP-3009)	`0x5425890298aed601595a70AB815c96711a31Bc65`
XSGD (test deployment / EIP-3009)	`0xd769410dc8772695A7f55a304d2125320A65c2a5`
ERC-8004 identity supported	Yes
AVAX faucet	core.app/tools/testnet-faucet
USDC faucet	Same faucet as AVAX

Use Fuji for development. Free, no real money at stake.

At-a-glance comparison

	Avalanche	Fuji	Base
Type	mainnet	testnet	mainnet
Chain ID	43114	43113	8453
Native USDC EIP-3009	✅	✅	✅
XSGD (SGD stablecoin, EIP-3009)	✅	✅	❌
Bridged USDC.e / USDT.e	✅	❌	❌
ERC-8004 identity	✅	✅	❌ (planned)
Real funds	yes	no	yes

Choosing a chain

Your situation	Use
First-time integration / testing	Fuji
Production, want lowest fees + AVAX gas tooling	Avalanche
Production, want Base ecosystem integration	Base — currently in limited service; prefer Avalanche today
Production, want on-chain identity (today)	Avalanche (Base coming; Solana devnet live)
Production, multi-chain	Avalanche + Solana; identity on Avalanche (+ Solana devnet)

Discovering chains and tokens at runtime

Don’t hardcode these in production. Pull the current list from the facilitator:

# chains + token addresses
curl https://x402.0xgasless.com/list

# tokens per chain WITH settlement mode + the EIP-712 domain to sign under
curl https://x402.0xgasless.com/tokens

/list contains chain IDs, token addresses, and aliases. /tokens additionally tells you, per token, whether it settles gaslessly with one signature (settlement: "eip3009", no approve) or needs a one-time approve of the relayer (settlement: "a402"), and the exact EIP-712 domain to sign. See Facilitator API → /tokens.

Paying with a specific token (e.g. XSGD)

Nothing about the x402 flow changes per token — you just point asset at the token you want and sign under that token’s domain:

GET /tokens → find the token on your chain. For XSGD on Avalanche: address 0xb2F8…096E, settlement: "eip3009", domain { name: "XSGD", version: "2" }.
Sign a TransferWithAuthorization typed message with the payer’s key: domain { name: "XSGD", version: "2", chainId: 43114, verifyingContract: <token address> }, message { from, to, value, validAfter, validBefore, nonce } (value in 6-decimal base units — "10000000" = 10 XSGD).
POST /settle with { paymentPayload: { token: <token address>, payload: { authorization, signature } }, paymentRequirements: { chainId: 43114 } }.

The facilitator submits transferWithAuthorization on-chain and pays the gas — the payer needs zero AVAX and no prior approve. Managed platform wallets (server wallets and agent wallets) can do the same via POST /v1/agent/x402/sign with "tokenSymbol": "XSGD" — the platform signs with the custodied key and enforces USD spend caps at the live SGD/USD rate.

Solana

Solana payments are live — same facilitator, same /verify + /settle endpoints, settlement kind svm-exact. The facilitator’s fee-payer wallet co-signs and pays all transaction fees, so the payer needs zero SOL, mirroring the gasless guarantee on EVM.

Field	Mainnet	Devnet
Network name	`solana`	`solana-devnet`
CAIP-2	`solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp`	`solana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1`
Fee payer (facilitator)	`897YkTt5b6mHJgs3CiJQS8mCHNeBaKAZXHZzPUEGYHK8`	same
USDC	`EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v`	`4zMMC9srt5Ri5X14GAgXhaHii3GnPAEERYPJgZJDncDU`
XSGD	`71S9cppWipeUEQDFngYwxjoxB6Sz1MUqX72byLsVYJqy`	`5qaqr42T127uirLEJbfjpzaETWCyuvJMXapkB1SeduAK` (test)
Settlement	`svm-exact`	`svm-exact`
ERC-8004 identity	Not yet (mainnet program deploy pending)	Yes — program `FJbdYy6auvgUNbSohFiKxCguUJzuUuuZ71eRHCfDuajc`
Explorer	solscan.io	solscan.io?cluster=devnet

Two things to know:

Discovery: Solana appears in GET /health and GET /tokens (entries with family: "svm"), but not in /list — that endpoint follows the EVM-shaped x402 listing format.
How it settles: instead of an EIP-712 signature, the payer signs a Solana transaction that transfers the SPL token, built with the facilitator’s feePayer as the transaction fee payer. POST it to /settle and the facilitator co-signs and submits. The Agent SDK (@0xgasless/agent v2.1+) does this for you.