Register on Aster

Registration authorizes a VOOI-managed agent on Aster to trade on your behalf. Your funds remain in your own Aster account. The agent can read account data and place spot and perpetual orders; it cannot withdraw.

This guide assumes that you already have an active VOOI API token. See API Tokens for how to obtain one.

Do you need to register?

Check whether your VOOI account already has Aster credentials via GET /user-exchange:

GET https://perps-api.vooi.io/user-exchange
Authorization: Bearer <token>

curl https://perps-api.vooi.io/user-exchange \
  -H "Authorization: Bearer <token>"

The response is an array of { exchange, valid } objects.

An entry with exchange: "aster" is present and its valid is true — your account is already connected. No action needed.
No aster entry is present, or the aster entry has valid: false — follow the steps below. A present-but-valid: false entry means the existing credentials no longer work and you need to re-register.

Aster does not require a prior deposit before registering, so there is no eligibility check to run first.

Prerequisites

An EVM wallet
An active VOOI API token

1. Prepare registration

Call POST /user-exchange/{exchange}/register/prepare with your wallet address. The optional referralCode field binds a referral code to the new account at registration. Omit it and the VOOI code is applied; it cannot be changed afterwards. See Points & rewards. The response contains:

a short-lived registrationToken
signData — a two-item array of EIP-712 typed data objects. You sign each one in order: [0] registers and approves the VOOI API agent (read, spot-trade, and perp-trade permissions; withdrawals disabled), [1] approves the VOOI builder used for order-time fee attribution.

POST https://perps-api.vooi.io/user-exchange/aster/register/prepare
Authorization: Bearer <token>
Content-Type: application/json

{
  "address": "0xYourWalletAddress"
}

curl -X POST https://perps-api.vooi.io/user-exchange/aster/register/prepare \
  -H "Authorization: Bearer <token>" \
  -H "Content-Type: application/json" \
  -d '{"address": "0xYourWalletAddress"}'

Response shape:

{
  "exchange": "aster",
  "registrationToken": "<opaque-token>",
  "signData": [
    { /* EIP-712 typed data — primaryType "Message" (registers and approves the VOOI API agent) */ },
    { /* EIP-712 typed data — primaryType "ApproveBuilder" (approves the VOOI builder) */ }
  ]
}

Each signData item has domain, message, primaryType, and types — pass each through to an EIP-712 signer (see step 2). The two items differ: [0] uses primaryType: "Message" (its message.msg carries the agent-registration parameters), [1] uses primaryType: "ApproveBuilder". Both domains use chainId: 56 (BSC). See the API reference for the full schema. The first signature grants VOOI an API agent with read, spot-trade, and perp-trade permissions; withdrawals are disabled. The agent is valid for 90 days by default. To choose a different expiry, pass agentExpiry (milliseconds since the Unix epoch) in the prepare request — it sets the expiry of the agent registered by the [0] signature. The registrationToken expires in 10 minutes. If it expires before you complete registration, call this endpoint again to get a new token.

Customize the builder approval

The second signature ([1], ApproveBuilder) approves a builder address that VOOI uses when routing orders on Aster, along with a maximum builder fee rate. Defaults are server-side: a VOOI-controlled builder, name VOOI, and a 0.0003 (3 bps) cap. To override any of these, pass them in the prepare body:

Field	Type	Description
`builderAddress`	EVM address	Builder address carried in the builder approval.
`builderName`	string	Builder display name.
`maxFeeRate`	decimal string	Cap on the per-order builder fee, as a decimal (not bps). `"0.0003"` = 3 bps.

builderName and maxFeeRate may only be sent together with builderAddress — sending either one alone returns 400. Once approved, this cap is enforced on every Aster order: the per-order broker.feeBps you submit cannot exceed it. Re-running registration with a different cap replaces the previous approval.

2. Sign both messages

Sign each signData object as EIP-712 typed data, in the same order as the response. Both messages use chainId: 56 (BSC). Many end-user wallet apps warn or refuse to sign typed data whose domain chainId does not match the active network — if you prompt an end-user wallet to sign, switch it to BSC first. Signing with a raw private key has no network to match against.

import { type Hex } from 'viem';
import { privateKeyToAccount } from 'viem/accounts';

async function signRegistration(
  walletPrivateKey: Hex,
  signData: PrepareResponse['signData'],
): Promise<[Hex, Hex]> {
  const account = privateKeyToAccount(walletPrivateKey);

  const sign = (item: (typeof signData)[number]) =>
    account.signTypedData({
      domain: {
        ...item.domain,
        chainId: Number(item.domain.chainId),
        verifyingContract: item.domain.verifyingContract as Hex,
      },
      message: item.message,
      primaryType: item.primaryType,
      types: item.types,
    });

  return [await sign(signData[0]), await sign(signData[1])];
}

This step returns two signatures that will be used in the next request to complete registration.

3. Execute registration

Submit your wallet address, the registrationToken, and both signatures to POST /user-exchange/{exchange}/register/execute. VOOI submits the signed messages to Aster on your behalf — you do not broadcast them yourself. No on-chain transaction is required. The signatures array must contain exactly two entries, in the same order as the signData items from the prepare response: index 0 is the agent registration-and-approval signature, index 1 is the builder-approval signature.

POST https://perps-api.vooi.io/user-exchange/aster/register/execute
Authorization: Bearer <token>
Content-Type: application/json

{
  "address": "0xYourWalletAddress",
  "registrationToken": "<opaque-token>",
  "signatures": ["0x<sig0>", "0x<sig1>"]
}

curl -X POST https://perps-api.vooi.io/user-exchange/aster/register/execute \
  -H "Authorization: Bearer <token>" \
  -H "Content-Type: application/json" \
  -d '{"address": "0xYourWalletAddress", "registrationToken": "<opaque-token>", "signatures": ["0x<sig0>", "0x<sig1>"]}'

Response on success:

{ "exchange": "aster", "valid": true }

Possible errors:

Status	Message	Cause
`400 Bad Request`	`Registration token has expired`	The token from step 1 expired. Call the prepare endpoint again to get a new one.
`400 Bad Request`	`Agent approval failed: ...`	Aster rejected the agent-registration signature (`[0]`). Confirm you signed the exact `signData` objects returned in step 1 and passed them in the correct order.

A failed builder approval ([1]) does not fail registration — the connection still completes with valid: true; only the agent-registration signature failing is fatal. Your wallet is now connected to Aster through VOOI.

Aster account configuration

Trading through VOOI expects your Aster account to be in:

Cross-margin mode
Multi-asset margin enabled
One-way position mode

Configure these in the Aster UI before trading. VOOI does not change these settings for you, and other modes are not supported by the abstracted trading endpoints.

Getting Started

Trading

Connect an Exchange

Points & rewards

Brokers

Do you need to register?

Prerequisites

1. Prepare registration

Customize the builder approval

2. Sign both messages

3. Execute registration

Aster account configuration

Next steps

Start trading on Aster

Connect your wallet to Hyperliquid

Connect your wallet to Extended

​Do you need to register?

​Prerequisites

​1. Prepare registration

​Customize the builder approval

​2. Sign both messages

​3. Execute registration

​Aster account configuration

​Next steps

Start trading on Aster

Connect your wallet to Hyperliquid

Connect your wallet to Extended

Do you need to register?

Prerequisites

1. Prepare registration

Customize the builder approval

2. Sign both messages

3. Execute registration

Aster account configuration

Next steps