Key Takeaways
The Binance WebSocket API enables real-time, bidirectional communication for market data retrieval, trading and account management.
Establishing a connection involves defining a WebSocket endpoint, with authentication required only for user-specific actions such as trading, and account management.
Requests must include unique identifiers to correlate responses with requests correctly.
WebSockets enable real-time streaming and continuous data flow but come with different trade-offs compared to the REST API.
Introduction
Binance provides different API solutions to facilitate automated trading and market data access. While REST APIs are widely used, they require polling for updates, which introduces additional overhead. The Binance WebSocket API offers an alternative by maintaining a persistent connection, reducing the need for repeated request-response cycles while enabling real-time data transmission.
By using WebSockets, traders and developers can significantly reduce network overhead, improve response times, and receive instant updates on trading pairs, orders, and market conditions. Understanding how to properly implement WebSockets ensures seamless integration with Binance’s ecosystem, providing a more robust and efficient trading experience. For a more in-depth understanding of WebSockets and how they function, refer to What is a WebSocket and How Does It Work?
This article explores the practical aspects of using the Binance WebSocket API, covering how to establish a connection, send requests, match responses, and authenticate sessions. Additionally, it discusses best practices for ensuring reliable WebSocket implementation and compares its advantages and disadvantages against the REST API, detailing best practices for efficient usage.
Connecting to Binance WebSocket API
To start using the Binance WebSocket API, a client must establish a connection to one of Binance’s WebSocket endpoints. The base WebSocket endpoint for the API is:
wss://ws-api.binance.com/ws-api/v3Binance also provides a testnet environment for users to test WebSocket functionality without interacting with the live market. The testnet WebSocket API can be accessed using the following endpoint:
wss://ws-api.testnet.binance.vision/ws-api/v3Establishing a WebSocket Connection
To interact with the Binance WebSocket API, a connection must be established first. WebSockets provide a persistent, full-duplex communication channel, allowing real-time data exchange.
When implementing WebSocket connections, it is important to:
Handle reconnections in case of network issues.
Manage timeouts and errors, as interruptions can occur due to server restarts, network instability, or API rate limits.
Monitor the connection state and respond appropriately to connection events, such as successful connections, disconnections, errors, and incoming messages.
Example: Establishing a Connection
Python Snippet:
import websocket
client = websocket.WebSocketApp(
"wss://ws-api.binance.com/ws-api/v3",
on_open=lambda ws: print("Connection opened"),
on_close=lambda ws, code, msg: print("Connection closed"),
on_error=lambda ws, error: print(f"Error: {error}"),
on_message=lambda ws, message: print(f"Message received: {message}")
)Sending a Basic Request
Once connected, users can request specific data, such as exchange information, which includes available trading pairs, rate limits, and API specifications.
Example: Fetching Exchange Information
Python Snippet:
import uuid
request = {
"id": str(uuid.uuid4()),
"method": "exchangeInfo",
"params": {
"symbol": "BNBUSDT"
}
}
client.send(request)
Understanding exchange information is critical for planning trading strategies and ensuring compliance with Binance’s rate limits and available markets.
Correlating Request with Response
Since WebSocket responses are asynchronous, multiple responses can arrive in any order. Each response includes the same ID value as the corresponding request, allowing clients to correlate them.
Tracking responses efficiently is crucial in high-frequency trading applications where multiple requests may be sent in parallel.
Best Practices for Managing Responses:
Use a structured approach to track sent request IDs and match them with corresponding responses, ensuring efficient request-response correlation.
Use timeouts to handle delayed responses and prevent hanging requests.
Log every request and response for debugging purposes.
Implement error-handling logic to detect failed requests and retry them if necessary.
Example: Fetching Exchange Information With Custom ID
Python Snippet:
request = {
"id": "your-tracked-id",
"method": "exchangeInfo",
"params": {
"symbol": "BNBUSDT"
}
}
client.send(request)
The response will include the same ID, helping to track the request.
Session Logon, Logout, and Status
For user-specific operations, such as placing trades or accessing account details, authentication is required. Binance WebSocket API allows a session logon to avoid authentication for every request.
Session Logon Benefits:
Reduces redundant authentication for every API request.
Ensures a secure, active session for a given API key.
Simplifies user data stream management by ensuring an authenticated connection remains open.
Maintaining an authenticated session improves efficiency, but users must be mindful that the authenticated session is only valid for that specific session and API key.
Session Logon
Logging into a session allows users to avoid including authentication credentials in every authenticated request. For WebSocket session logon, only Ed25519 keys are supported—HMAC and RSA authentication methods are not available for this feature.
Ed25519 is a modern cryptographic signature algorithm that provides high security, compact key sizes, and fast verification, making it well-suited for real-time WebSocket authentication.
Example: Authenticating a Session
Python Snippet:
import time
import uuid
from urllib.parse import urlencode
from base64 import b64encode
from Crypto.PublicKey import ECC
from Crypto.Signature import eddsa
api_key = "your_api_key"
private_key = "your_private_key"
private_key_passphrase = "your_private_key_passphrase"
timestamp = int(time.time() * 1000)
# Create Ed25519 signature
payload = {"timestamp": timestamp}
signature_payload = urlencode(payload, True).replace("%40", "@")
private_key = ECC.import_key(private_key, passphrase=private_key_passphrase)
signer = eddsa.new(private_key, "rfc8032")
signature = b64encode(signer.sign(signature_payload.encode("utf-8")))
request = {
"id": str(uuid.uuid4()),
"method": "session.logon",
"apiKey": api_key,
"timestamp": timestamp,
"signature": signature
}
client.send(request)
NOTE: Before using requests like user data streams subscription, a session logon request must be sent.
Session Status
After logging in, users can check the current session status to verify authentication and connection status.
Example: Checking Session Status
Python Snippet:
import uuid
request = {
"id": str(uuid.uuid4()),
"method": "session.status"
}
client.send(request)NOTE: This request helps confirm whether the session is active and authenticated before sending further API requests.
Session Logout
To securely close the authenticated session, users can use the session.logout method. This ensures that the API key is no longer associated with the WebSocket connection.
Example: Logging Out of a Session
Python Snippet:
import uuid
request = {
"id": str(uuid.uuid4()),
"method": "session.logout"
}
client.send(request)NOTE: Logging out will terminate authentication for the current WebSocket session. To send further authenticated requests, users must log in again using session.logon.
Proper handling of session management is critical to maintaining connection stability and preventing disruptions.
Advantages and Disadvantages of WebSocket API vs. REST API
Advantages of WebSocket API:
Persistent Connection – A continuous WebSocket connection removes the need for repeated requests, ensuring real time data updates.
Efficient Resource Usage – Fewer requests reduce bandwidth and API rate limits.
Bidirectional Communication – Enables sending and receiving data simultaneously.
Scalability – Allows multiple simultaneous data streams in a single connection, reducing network overhead.
Push-Based Updates – Unlike REST APIs that require polling, WebSockets push updates in real-time, reducing redundant requests.
Disadvantages of WebSocket API:
Persistent Connection Required – Clients must manage an active connection.
Error Handling Complexity – Managing reconnects and timeouts requires additional logic.
Rate Limits and Subscription Limits – Each connection can only subscribe to a certain number of streams, requiring careful management in high-frequency applications.
Increased Complexity for Stateless Applications – Unlike REST, WebSockets require session maintenance, making it harder to scale stateless applications.
Closing Thoughts
The Binance WebSocket API provides a persistent, real-time interface for market data and trading automation. Understanding how to manage session logon, correlate responses, and handle connection stability is crucial for efficient API interactions.
For developers looking to optimize API usage, combining WebSockets for live data updates with REST API for historical data retrieval is often the best approach.
Additionally, handling rate limits, error scenarios, and session timeouts properly can significantly improve the reliability of WebSocket-based applications. Proper monitoring tools, such as latency tracking, reconnection logic, and API usage alerts, should be implemented to ensure smooth operation in production environments.
Binance also offers WebSocket Streams specifically for real-time market data streaming, which differs from the WebSocket API used for authenticated trading and account management. If your use case primarily involves streaming market data without sending requests, consider using WebSocket Streams for a more relevant solution.
By following the best practices outlined in this guide, developers can build efficient, high-performance trading applications using Binance’s WebSocket API.
Further Reading
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