> ## 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.
# Build on Base
> Base network config, the canonical ERC-8004 registries verified live there, and our x402 rail wired to settle in native Circle USDC.
Base is Coinbase's Ethereum L2 and one of the busiest agent ecosystems on any chain.
A-Identity holds ERC-8004 agent **#73232** on the canonical registry here and settles
paid trust calls in native Circle USDC through its own EIP-3009 facilitator.
## Why Base
Real USDC, not a bridged twin, and it implements EIP-3009, so a buyer can sign a transfer and never touch gas.
The canonical identity and reputation registries were deployed here by their authors, at the same addresses X Layer, Celo, Robinhood Chain and Arbitrum One carry.
The x402 standard grew up around this ecosystem. Running our rail here puts the same code path and receipt standard next to the crowd it was designed for.
Base is **live** for us: agent #73232 is ours on the canonical registry (minted
2026-08-28), and a real settlement in USDC has gone through our own facilitator with
the receipt carrying the matching Transfer log. Everything on this page, including
the Stellar funding hop behind the operating wallets, is checkable at
[/proof/base](https://a-identity.xyz/proof/base).
## Network config
| Field | Value |
| --------------- | ----------------------------------------------------------------------- |
| Chain ID | `8453` |
| CAIP-2 | `eip155:8453` |
| Native currency | ETH (18 decimals) |
| RPC (HTTP) | `https://mainnet.base.org` (fallback `https://base-rpc.publicnode.com`) |
| Block explorer | [basescan.org](https://basescan.org) |
| USDC | `0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913` |
| CCTP domain | `6` |
A verification trap specific to this chain, recorded so nobody falls into it twice:
Arc's three testnet-era registry addresses **also have code on Base**, 130 bytes each,
minimal-proxy sized, delegating to a NON-canonical implementation. Same address,
different contract. `eth_getCode` answering "yes" therefore means nothing here. The
canonical pair below was verified by reading each proxy's EIP-1967 implementation
slot and matching the implementation bytecode byte for byte against Arbitrum One
(2026-08-28).
## Connect with viem
```ts chain.ts theme={null}
import { base } from 'viem/chains'
import { createPublicClient, http } from 'viem'
export const client = createPublicClient({ chain: base, transport: http() })
```
```ts read.ts theme={null}
import { client } from './chain'
// The canonical registry answers live: name() is "AgentIdentity" and minted
// tokens resolve. Registration on it is permissionless.
const name = await client.readContract({
address: '0x8004a169fb4a3325136eb29fa0ceb6d2e539a432',
abi: [{ type: 'function', name: 'name', stateMutability: 'view', inputs: [], outputs: [{ type: 'string' }] }],
functionName: 'name',
})
```
## What is deployed
| Contract | Address |
| ------------------ | ----------------------------------------------------------------------------------------------------------------------- |
| IdentityRegistry | [`0x8004a169fb4a3325136eb29fa0ceb6d2e539a432`](https://basescan.org/address/0x8004a169fb4a3325136eb29fa0ceb6d2e539a432) |
| ReputationRegistry | [`0x8004BAa17C55a88189AE136b182e5fdA19dE9b63`](https://basescan.org/address/0x8004BAa17C55a88189AE136b182e5fdA19dE9b63) |
| USDC (settlement) | [`0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`](https://basescan.org/address/0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) |
We deployed none of these. The registries were already live and registering on them is
permissionless; what is ours is agent #73232 and the rail on top. There is no
ValidationRegistry in this family, so a KYA result cannot be anchored on-chain here.
## The price, and where it comes from
The base price of a tool is identical on every chain we sell on; the only difference is
the disclosed settlement fee, because we broadcast on the buyer's behalf and that costs
gas. On Base a real settlement measured **102828 gas at an effective 0.006 gwei**
(2026-08-28), about **0.00000062 ETH** including the L1 data fee, roughly $0.0025, so
the fee here is **$0.005\*\*: the same 2x-headroom logic as Arbitrum One, against a base
fee that sits near its floor rather than moving. The measurement lives in the chain
registry beside the token, so the number is traceable rather than asserted.
## Verify it yourself
```bash theme={null}
# The signing domain, straight from the token.
curl -sX POST https://mainnet.base.org -H 'content-type: application/json' \
-d '{"jsonrpc":"2.0","id":1,"method":"eth_call","params":[{"to":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","data":"0x3644e515"},"latest"]}'
# -> 0x02fa7265e7c5d81118673727957699e4d68f74cd74b7db77da710fe8a2c7834f
# Our agent on the canonical registry, answering live: ownerOf(73232).
curl -sX POST https://mainnet.base.org -H 'content-type: application/json' \
-d '{"jsonrpc":"2.0","id":2,"method":"eth_call","params":[{"to":"0x8004a169fb4a3325136eb29fa0ceb6d2e539a432","data":"0x6352211e0000000000000000000000000000000000000000000000000000000000011e10"},"latest"]}'
# -> 0x...d305607510e0db2c95807173c7a05bea53c1ed36
# Our provenance ledger for this rail, re-read live on every request.
curl -s https://a-identity-backend.onrender.com/api/proof/base
```
## Where Base fits
[Arbitrum One](/chains/arbitrum) is where the same rail runs against a well-served
baseline; [Robinhood Chain](/chains/robinhood) is where it runs on a chain with no
published facilitator; [Arc](/chains/arc) holds escrow and the spend vault. Base is
where the agent ecosystem itself lives, and the [Gateway](/chains/gateway) hop already
proves USDC minted on Base Sepolia from an Arc deposit.