> ## Documentation Index
> Fetch the complete documentation index at: https://docs.blink15.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Python SDK

> Install and configure py-blink-client for trading on Blink

## Installation

```bash theme={null}
pip install py-blink-client
```

Or from source:

```bash theme={null}
git clone https://github.com/BlinkExchange/py-blink-client
cd py-blink-client
pip install -e .
```

### Requirements

* Python 3.10+
* `eth-account` (EIP-712 signing)
* `requests` (HTTP)
* `websockets` (real-time data)

## Connect and Authenticate

```python theme={null}
from py_blink_client import ClobClient

# Public data only (no auth needed)
client = ClobClient(host="https://api.blink15.com")

# Trading (requires wallet private key)
client = ClobClient(
    host="https://api.blink15.com",
    key="0xYOUR_PRIVATE_KEY",
)

# Create API credentials (one-time — cached on the client)
creds = client.create_or_derive_api_creds()
print(f"API Key: {creds.api_key}")
```

<Warning>
  Your private key never leaves your machine. It's only used locally to sign an EIP-712 message that proves wallet ownership.
</Warning>

## How Auth Works

Blink uses two auth levels (same as Polymarket):

**Level 1 — EIP-712 (one-time setup)**

Your wallet signs a typed data message to create API credentials. This happens once when you call `create_or_derive_api_creds()`.

**Level 2 — HMAC-SHA256 (every request)**

All trading requests are signed with HMAC. The SDK handles this automatically after credentials are created.

```python theme={null}
# After create_or_derive_api_creds(), all calls use HMAC auth
orders = client.get_orders()              # authenticated
client.create_and_post_order(...)         # authenticated
client.cancel(...)                        # authenticated
```

## Configuration

| Parameter  | Default                   | Description                                    |
| ---------- | ------------------------- | ---------------------------------------------- |
| `host`     | `https://api.blink15.com` | API base URL                                   |
| `key`      | `None`                    | Wallet private key (hex string with 0x prefix) |
| `chain_id` | `84532`                   | Base Sepolia chain ID                          |

## Error Handling

The SDK raises `BlinkApiError` for HTTP errors and `BlinkAuthError` for authentication failures:

```python theme={null}
from py_blink_client import BlinkApiError, BlinkAuthError

try:
    order = client.create_and_post_order(args)
except BlinkAuthError as e:
    print(f"Auth failed: {e}")  # expired or invalid credentials
except BlinkApiError as e:
    print(f"API error {e.status_code}: {e.response_body}")
```

The SDK automatically retries on 5xx errors (3 attempts with exponential backoff).

## Testnet Faucet

Get free USDC on Base Sepolia:

```python theme={null}
# Mint 100 USDC
result = client.claim_faucet("0xYourWalletAddress")
print(f"TX: {result['tx_hash']}")

# Gas-free USDC approval
client.relay_permit(owner, spender, value, deadline, v, r, s)

# Sponsor ETH for CTF token approval
client.prefund_ctf_approval("0xYourWalletAddress")
```

## What's Next

<CardGroup cols={2}>
  <Card title="Trading" icon="arrows-rotate" href="/sdk/python-trading">
    Place orders, batch operations, order types
  </Card>

  <Card title="WebSocket Streams" icon="bolt" href="/sdk/python-websocket">
    Real-time orderbook, fills, price ticks
  </Card>
</CardGroup>