Why Agent402 settles on fourteen chains instead of just Base

Most x402 volume, ours included, settles on Base. That's not a secret and this guide isn't going to pretend otherwise. So the honest question is: why run thirteen more rails if that's where the traffic already is?

The reason isn't "more chains, more revenue"

It's optionality. An agent doesn't get to choose what chain its wallet already holds USDC on - it was funded once, for some other reason, on whatever chain that happened to be. A seller who only accepts Base is invisible to every agent funded anywhere else, no matter how good the tool is. Fourteen chains means fourteen populations of already-funded buyers who never have to bridge, swap, or wait for a transfer just to pay for one API call.

What's actually live, and who settles it

Every rail below is a real, working payTo you can quote against right now. Each tool's 402 (or GET https://agent402.tools/api/x402-quote?url=...) lists its live accepts per network, and /api/rails lists the rails offered. Each rail settles through a facilitator that supports it, with a fallback where one exists:

  • Base - the primary rail, and where the x402 Bazaar discovery listing lives.
  • Solana, Polygon, Arbitrum, Avalanche, Sei, Monad, Celo - USDC, each through a facilitator that settles that network.
  • Optimism - USDC; its settlement carries a fee, so its quote carries a small network premium, shown in the 402. What you're quoted is what actually clears.
  • Arc - USDC, through the facilitator that settles that network; Arc pays its own gas in USDC, and the facilitator covers it, so a buyer needs only USDC.
  • Stellar - USDC via our own self-hosted Soroban facilitator (open source, in this repository); settlement here is confirmed against the chain itself, not just trusted from the facilitator's word, because Stellar's ~5-second ledger close can outlast a synchronous HTTP request.
  • Algorand - USDC via a dedicated AVM facilitator; every payment carries a signed validity window sized to the tool it's paying for, so a slow tool can never receive a payment that expires mid-call.
  • Robinhood Chain - the one non-USDC rail: USDG. Its quote never goes below $0.01 a call, shown in the 402.

Every facilitator is health-checked at boot. A facilitator that fails its boot check drops only its own rail from the offer - the other rails, and the free proof-of-work tier, are unaffected.

What doesn't change per chain

The settlement rule is the same everywhere: a call that answers an error status, or whose payment does not match the offer, is not settled, on any of the fourteen chains. Chain choice changes where the USDC moves, not the rule that decides whether it moves.

The Smart Order Router uses this directly

When the router buys from an external seller to resell the result to you, it settles on the SAME chain you paid it on - an Algorand payment funds an Algorand purchase, a Base payment funds a Base purchase. Fourteen chains isn't just about who can pay us; it's what lets the router keep your money on the chain you already trusted it on, instead of quietly routing everything through one chain regardless of what you sent.

Packages for this guide

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