> For the complete documentation index, see [llms.txt](https://docs.nexus.xyz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.nexus.xyz/api-reference/agents/register-agent.md).

# POST /agents/register

Register an agent key.

`operationId`: `registerAgent`

**Authentication:** none declared, and the contract declares no document-level default — this operation carries its own signature in the request body. See the description above.

Register a new agent key for your wallet. An agent is an Ethereum-derived keypair that can sign trading requests on your behalf without exposing your main wallet. The registration is authorized by an EIP-712 signature from the wallet that will own the agent — no session token required.

EIP-712 domain: `{ name: 'Nexus Exchange', version: '1', chainId: <per-network chain id> }`. The `chainId` is **network-scoped**: read `signing_domain.chain_id` from `/metadata` for the network you are connected to (see `x-nexus-networks`) instead of hardcoding it, and refuse to sign if you cannot obtain it — a wrong domain either fails verification or produces a signature that is valid somewhere you did not intend. Mainnet is the real-funds exchange on Ethereum Mainnet, not a Nexus L1 chain, so a Nexus L1 chain id is never correct there. Because the domain differs per network, a registration signed for one network does not verify on another; never replay one across networks. Typed data type: `RegisterAgent { address agent, uint64 expiresAt, uint64 nonce }`.

## Request body

**Required.** [`AgentRegistrationRequest`](/api-reference/guides/schemas.md#agentregistrationrequest) — `application/json`.

```json
{
  "wallet": "0xAbCdEf0123456789AbCdEf0123456789AbCdEf01",
  "agent": "0x1234567890AbCdEf1234567890AbCdEf12345678",
  "expires_at": 1782000000000,
  "nonce": 1,
  "signature": "0xdeadbeef..."
}
```

## Responses

| Status | Body                     | Meaning                                                                                              |
| ------ | ------------------------ | ---------------------------------------------------------------------------------------------------- |
| `200`  | — *(no schema declared)* | Agent registered                                                                                     |
| `400`  | — *(no schema declared)* | Bad request: bad\_wallet, bad\_agent, expiry\_out\_of\_range \[1 d, 90 d from now], or invalid\_json |
| `401`  | — *(no schema declared)* | signature\_invalid or signer\_mismatch — the EIP-712 signature did not recover to the claimed wallet |
| `409`  | — *(no schema declared)* | duplicate\_agent — the agent address is already registered to this wallet                            |

## Example

```bash
curl -X POST 'https://exchange.nexus.xyz/api/exchange/agents/register' \
  -H 'Content-Type: application/json'
```

***

<sub>Generated from</sub> <sub></sub><sub>`eng/apps/exchange/api/openapi.json`</sub> <sub></sub><sub>(spec</sub> <sub></sub><sub>`0.9.27`</sub><sub>). Do not edit by hand — regenerate with</sub> <sub></sub><sub>`python3 product/docs/tools/api-reference/generate.py`</sub><sub>. Hand-authored context lives in the Guides pages.</sub>


---

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