Today, PayAI is adding Arbitrum to the list of networks supported by our x402 facilitator.

Integrations with compatible EVM clients and server software can accept payments on Arbitrum through PayAI’s existing x402 endpoints. Configure the network, asset and payment scheme, then test the complete request and recovery flow. Adding a network name alone does not prove that an older SDK supports it.

Arbitrum gives EVM-based services another network on which to accept payments. This article no longer asserts an L2 ranking or stablecoin totals without a dated measurement and defined metric. For changing market data, consult a source such as DefiLlama’s Arbitrum stablecoin page and record when it was measured.

PayAI also provides the payment facilitation described in our Pay.sh integration article. Adding Arbitrum expands network choice; it does not establish a market-share rank or make different chains interchangeable.

What ships today

The live /supported response advertises exact payments for Arbitrum One and Arbitrum Sepolia in x402 v1 and v2, checked September 13, 2026 UTC. That is advertised support, not a new production payment test.

  • USDC settlement on Arbitrum One. The EVM implementation also handles compatible EIP-3009 token authorizations; this is not a USDC-only protocol. Confirm the deployed token contract, signing domain, client and network before offering another asset. A token symbol or a deployment on another chain is not sufficient. In this flow, the payer signs an authorization and the facilitator submits the transaction. That avoids a separate ERC-20 allowance transaction for this authorization flow; gas still has a payer, and facilitator fees may apply. Other schemes can have different approval requirements.
  • Existing facilitator endpoints. Configure a compatible SDK and middleware version for the target network; do not assume every Python, TypeScript or Go release works unchanged.
  • The same /verify, /settle and /supported API paths. A shared API does not make all networks’ timing, confirmation guarantees, assets or recovery behavior identical.
  • Same facilitator pricing. Up to 1,000 lifetime settlements per receiving wallet are free, subject to shared host/IP pools; beyond the free tier, the facilitator fee is $0.001 per settlement.
  • Testnet support. Build and verify against Arbitrum Sepolia before flipping production traffic over.

Use the Supported Networks page for identifiers and the quickstart for integration steps. Test the selected client, server and payment terms together before changing production traffic.

Why Arbitrum

Arbitrum describes configurable platform performance including fast response times and high throughput. Those platform figures are not measured PayAI payment latency or a finality guarantee for Arbitrum One. Its finality documentation distinguishes provisional sequencer confirmation from parent-chain finality. Measure end-to-end request latency and total costs for your integration.

Arbitrum’s blockchain and AI overview discusses agent applications and their infrastructure challenges. Those examples give developers context, but they do not establish that those projects use PayAI or x402.

PayAI’s multi-network strategy gives developers choices behind a common API. Clients, resource servers and facilitators still need compatible versions, schemes, networks and assets. Service discovery is separate; accepting payment does not guarantee inclusion in every index.

"x402 is winning because it's chain-agnostic and facilitator-agnostic. Arbitrum has been one of the most-requested networks from teams shipping on PayAI — they have their stack on EVM, their stablecoins on Arbitrum, and they want their agents paying for things on the same rails. Today they can." — Notorious, founder at PayAI (@notorious_d_e_v)

What this unlocks

A few of the use cases we expect to ship on Arbitrum + x402 first:

  • EVM-native agent payments. A client with authorized wallet access, supported USDC and compatible software can request and pay for resources. Merchant authentication and service access requirements remain separate.
  • API monetization for Ethereum builders. APIs deployed in EVM-native dev environments can now monetize per request without leaving the L2 their team and treasury already live on.
  • Multi-network agent flows. An agent could pay services on Solana, Arbitrum and Base if it has compatible clients and funds on each chosen network. The facilitator does not bridge those balances between chains.
  • Payment-aware API design. Measure the initial challenge, signed retry, verification, settlement and resource delivery together. A fast network confirmation does not make the paid request as fast as an unpaid one.

For builders

If you already use PayAI, check your SDK’s configuration format. The v1 identifiers are arbitrum (mainnet) and arbitrum-sepolia (testnet); the v2 CAIP-2 identifiers are eip155:42161 and eip155:421614 respectively. Configure the matching asset and scheme as well. See the network reference and quickstart.

If you are new to x402, read the protocol overview and run the quickstart. Start on testnet and exercise failure cases; this article does not promise a production integration in ten minutes.

For discovery, check how your intended clients find services and how your endpoint is listed. Facilitator integration alone does not make it discoverable to every agent framework.

Arbitrum adds a payment-network option for teams whose wallets and services can use it. Keep chain-specific funding, confirmation and recovery requirements explicit.

Let's build.

Frequently asked questions

Is x402 live on Arbitrum? Yes: PayAI’s documentation lists Arbitrum One and Sepolia, and the public /supported response advertised exact payments for both at the September 13, 2026 UTC check. That read-only check does not certify every asset or client integration.

Do I need a new SDK? It depends on your installed version and integration. Use a compatible EVM implementation, the correct network identifier and supported payment terms. Do not infer out-of-the-box support from the SDK language alone.

Which tokens can I use? USDC is the documented default on Arbitrum One. The EVM flow can handle compatible EIP-3009 authorizations, but a list of token symbols is not a verified list of Arbitrum deployments. Check the actual contract, signing domain, scheme and client before accepting another token.

What does x402 on Arbitrum cost? PayAI offers up to 1,000 lifetime free settlements per receiving wallet. Shared host/IP pools can reach the limit sooner. Beyond the free tier, merchants use API credentials and credits at $0.001 per settlement. This facilitator fee is designed to cover gas and RPC costs; it is separate from the price a merchant charges for its API. See the current facilitator pricing.

What other networks does PayAI support? Alongside Arbitrum, the documentation lists Solana, Base, SKALE Base, Polygon, Avalanche, Sei and X Layer, with the listed development or test networks. Use the current network reference and /supported response for exact identifiers and advertised schemes.

Can an AI agent pay on Arbitrum? Yes, when it has delegated signing authority, funds and compatible payment software, and the service accepts those terms. The application must enforce spending limits, access requirements and failure handling.

Follow @PayAINetwork for what ships next.

Integration references: Merchant authentication · Facilitator pricing · Exact-payment flow