> ## Documentation Index > Fetch the complete documentation index at: https://a-identity.mintlify.site/llms.txt > Use this file to discover all available pages before exploring further. # Chains > Every chain A-Identity knows about, what is actually deployed on each, and which ones are wired end to end today. A-Identity is chain-agnostic by construction: one registry describes every chain, and one adapter per virtual machine does the work. Adding a chain is a data edit, not a new code path. The table below is the honest state of that registry. The vocabulary is exact. **Live** means wired end to end and carrying real traffic. **Beta** means real and reachable, but not the whole loop. **Planned** means the descriptor exists so onboarding is a data edit, and nothing is deployed yet. | Chain | CAIP-2 | Status | What is deployed | | -------------------------------------------- | ----------------- | ------- | ---------------------------------------------------------------------------------------------------------------------------- | | [Circle Arc](/chains/arc) (testnet) | `eip155:5042002` | live | ERC-8004 identity, reputation and validation, ERC-8183 escrow, AgentSpendPolicy vaults, USDC | | [OKX X Layer](/chains/xlayer) | `eip155:196` | live | Canonical ERC-8004 identity; the trust oracle is listed here and sells over x402 | | [Robinhood Chain](/chains/robinhood) | `eip155:4663` | live | Canonical ERC-8004 identity and reputation, agent #0, and our own x402 facilitator settling in USDG | | [Celo](/chains/celo) | `eip155:42220` | live | Canonical ERC-8004 identity and reputation, agent #9759, x402 over USDC via the first-party Celo facilitator | | Base | `eip155:8453` | beta | Payment path only. No ERC-8004 registry is deployed on Base mainnet, and we do not assert one | | [Robinhood Chain Testnet](/chains/robinhood) | `eip155:46630` | beta | The full canonical ERC-8004 trio plus a deployed AgentSpendPolicy vault | | [Celo Sepolia](/chains/celo) | `eip155:11142220` | beta | Same ERC-8004 pair as Arc, x402 over testnet USDC | | Stellar | `stellar:pubnet` | planned | Descriptor only. Identity would be a Soroban registry plus SEP-10, not ERC-8004 | | Stellar (testnet) | `stellar:testnet` | planned | Where the Soroban vault and the x402 path are rehearsed before pubnet | | Avalanche C-Chain | `eip155:43114` | planned | Descriptor only | | [Arbitrum One](/chains/arbitrum) | `eip155:42161` | live | Canonical ERC-8004 identity and reputation, agent #1259, and x402 settling in native Circle USDC through our own facilitator | This table is maintained against the registry itself, and a test in the backend fails the build if a chain here disagrees with it. The machine-readable version is `GET /api/chains`, which is generated from the same source. ## What "deployed" means for identity The ERC-8004 registries are not ours. Their authors deployed them deterministically, so the same addresses appear on chain after chain, and where they were already present we simply read them. Where a piece was missing we reproduced it by replaying the canonical deployment calldata rather than forking a new contract, which is why the addresses still match everywhere. Two consequences worth stating plainly, because they are easy to get wrong: * A chain can carry an IdentityRegistry and no ValidationRegistry. On those chains a KYA result cannot be anchored on-chain. It is still verified and recorded, and we say so rather than reporting a zero that reads like a real count. * A chain can have a real settlement token and no canonical Circle USDC. Robinhood Chain is exactly that: the registry's USDC slot stays empty on purpose, and USDG is named as its own thing, because every generic USDC code path reads that slot. ## Settlement, chain by chain | Rail | How a payment settles | | --------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Arc | The buyer broadcasts an ERC-20 transfer; we verify the receipt ourselves. Also gasless Circle Nanopayments. | | X Layer | Through the OKX facilitator, as a listed ASP service. | | Celo | Through Celo's own first-party x402 facilitator, EIP-3009, buyer pays no gas. | | Robinhood Chain | Through **our own** facilitator, run because no published one serves this chain: EIP-3009, buyer pays no gas, and settlement is proven by a receipt carrying the matching Transfer log. | | Arbitrum One | The same facilitator and the same engine, settling in native Circle USDC. Other facilitators already serve this chain, so here you can compare ours against a baseline. The disclosed fee is lower because a settlement measurably costs less: 103569 gas at 0.02 gwei. |