👋 Welcome to cross402

cross402 is a developer-first programmable payment layer for USDC. A single intent routes value from any supported payer chain to any supported target chain — the caller picks both ends, cross402 handles the settlement.

Why cross402?

Any-chain to any-chain settlement. Payers can currently send USDC from Solana, Base, Ethereum, Polygon, and HyperEVM. Merchants can receive on any of those same chains — GET /api/chains is authoritative for what's callable right now. Every intent settles through the x402 protocol on both the payer side and the target side; the SDK picks the right signing flavor (EIP-3009, Permit2+EIP-2612, or Solana VersionedTransaction) for each chain automatically.

Roadmap: Arbitrum, BSC, Monad, SKALE Base, and MegaETH are documented in Supported Chains for integration preparation; they are 🚧 coming soon and will return 400 until enabled.

Agent-led automation. Managed agent wallets execute target-chain payouts so your backend doesn't hold hot keys per chain.

Developer first. Native SDKs for JS/TS and Go, covering everything from web checkouts to backend payout jobs.

Get Started with the Quick Start Guide →

v2 Breaking Notes

cross402 v2 removed the assumption that payments settle on Base. Three things changed from v1:

New optional request field target_chain on CreateIntent. Defaults to "base", so v1 callers that only pass payer_chain continue to work.
Status enum renamed: BASE_SETTLING → TARGET_SETTLING, BASE_SETTLED → TARGET_SETTLED. The old names are gone; SDK constants renamed accordingly (IntentStatus.BaseSettled → TargetSettled, pay.StatusBaseSettled → pay.StatusTargetSettled).
Response field renamed: base_payment is now target_payment on the GetIntent response. SDK accessors renamed (intent.basePayment → intent.targetPayment, intent.BasePayment → intent.TargetPayment).

For the full before/after and a search-and-replace checklist, see v2 Migration: Any-Chain → Any-Chain.