`Client.API_URL` defaults to live endpoint despite `testnet=True`

[kaqsam7]

Describe the bug
The Client object's API_URL attribute is incorrectly set to the live Binance API endpoint (https://api.binance.com/api) when testnet=True is passed during initialization. It should point to the Testnet endpoint (https://testnet.binance.vision/api). Fortunately, i found a workaround online. Its very likely this is already known but i could not find an official Binance solution.

To Reproduce
Code snippet to reproduce the behaviour:

import logging
from binance.client import Client

API_KEY = "YOUR_TESTNET_API_KEY"
API_SECRET = "YOUR_TESTNET_API_SECRET"
USE_TESTNET = True # This should be True

client = Client(API_KEY, API_SECRET, testnet=USE_TESTNET)

print(f"testnet flag passed to Client: {USE_TESTNET}")
print(f"client.testnet attribute: {client.testnet}")
print(f"client.API_URL: {client.API_URL}")

try:
    if USE_TESTNET:
        account_info = client.get_account()
        print(f"Successfully fetched account info from: {client.API_URL}")
        print(f"Account Info (Testnet): {account_info.get('makerCommission')}, Balances: {len(account_info.get('balances', []))}")
except Exception as e:
    print(f"Error during API call: {e}")

Expected behavior
When testnet=True is passed to the Client constructor, client.API_URL should be https://testnet.binance.vision/api.

Environment (please complete the following information):

• Python version: - [3.11.7]
• Virtual Env: - [venv]
• OS: - [Windows 11]
• python-binance version - [1.0.29]

Logs
Please set logging to debug and paste any logs here, or upload debug.log file to the issue.
(Note: The "override" messages in the log are from the local workaround).

2025-05-23 07:15:52 - binance_api_manager - DEBUG - Client object created: Initial API_URL=https://api.binance.com/api, testnet_flag_passed=True
2025-05-23 07:15:52 - binance_api_manager - WARNING - Initial API_URL (https://api.binance.com/api) is not the expected Testnet URL (https://testnet.binance.vision/api) despite testnet=True. Manually overriding API_URL.
2025-05-23 07:15:52 - binance_api_manager - DEBUG - Effective API_URL after potential override: https://testnet.binance.vision/api
2025-05-23 07:15:53 - binance_api_manager - INFO - Account info retrieved: makerCommission=0, balances count=409
2025-05-23 07:15:53 - binance_api_manager - DEBUG - Effective API endpoint reported by client after get_account: https://testnet.binance.vision/api

Additional context
I am using what I believe to be the latest version of python-binance. I understand recent updates (like PR #1583) were made concerning Testnet URLs, but this behavior is still observed.
My current workaround is to manually set client.API_URL = 'https://testnet.binance.vision/api' after client initialization if testnet=True and the client.API_URL is incorrect. This workaround allows me to connect to the Testnet successfully.

[carlosmiei]

@kaqsam7 Thanks for reporting it, I will check it and get back to you.

[carlosmiei]

@kaqsam7 Can you please double check your python-binance version? I just tested using the testnet and it worked as expected

async def main():
    client = Client(api_key, api_secret=secret, testnet=True)

    res = client.get_account()
    print('after', res)

response

after {'makerCommission': 0, 'takerCommission': 0, 'buyerCommission': 0, 'sellerCommission': 0, 'commissionRates': {'maker': '0.00000000', 'taker': '0.00000000', 'buyer': '0.00000000', 'seller': '0.00000000'}, 'canTrade': True, 'canWithdraw': True, 'canDeposit': True, 'brokered': False, 'requireSelfTradePrevention': False, 'preventSor': False, 'updateTime': 1747848074618, 'accountType': 'SPOT', 'balances': [{'asset': 'ETH', 'free': '2.43000000', 'locked': '0.00000000'}, {'asset': 'BTC', 'free': '1.00000000', 'locked': '0.00000000'}, {'asset': 'LTC', 'free': '5.00000000', 'locked': '0.00000000'}, {'asset': 'BNB', 'free': '1.00000000', 'locked': '0.00000000'}, {'asset': 'USDT', 'free': '7401.16452000', 'locked': '0.00000000'}, {'asset': 'TRX', 'free': '2022.00000000', 'locked': '0.00000000'}, {'asset': 'XRP', 'free': '233.00000000', 'locked': '0.00000000'}, {'asset': 'NEO', 'free': '89.00000000', 'locked': '0.00000000'}, {'asset': 'QTUM', 'free': '238.00000000', 'locked': '0.00000000'}, {'asset': 'EOS', 'free': '691.00000000', 'locked': '0.00000000'}, {'asset': 'GAS', 'free': '161.00000000', 'locked': '0.00000000'}, {'asset': 'LRC', 'free': '4859.00000000', 'locked': '0.00000000'}, {'asset': 'ZRX', 'free': '1978.00000000', 'locked': '0.00000000'}, {'asset': 'KNC', 'free': '1459.00000000', 'locked': '0.00000000'}, {'asset': 'IOTA', 'free': '2402.00000000', 'locked': '0.00000000'}, {'asset': 'LINK', 'free': '36.00000000', 'locked': '0.00000000'}, {'asset': 'XVG', 'free': '18446.00000000', 'locked': '0.00000000'}, {'asset': 'MTL', 'free': '633.00000000', 'locked': '0.00000000'}, {'asset': 'ETC', 'free': '30.00000000', 'locked': '0.00000000'}, {'asset': 'ZEC', 'free': '13.00000000', 'locked': '0.00000000'}, {'asset': 'DASH', 'free': '23.00000000', 'locked': '0.00000000'}, {'asset': 'REQ', 'free': '3614.00000000', 'locked': '0.00000000'}, {'asset': 'POWR', 'free': '2957.00000000', 'locked': '0.00000000'}, {'asset': 'ENJ', 'free': '6688.00000000', 'locked': '0.00000000'}, {'asset': 'STORJ', 'free': '1813.00000000', 'locked': '0.00000000'}, {'asset': 'KMD', 'free': '3567.00000000', 'locked': '0.00000000'}, {'asset': 'BAT', 'free': '3613.00000000', 'locked': '0.00000000'}, {'asset': 'LSK', 'free': '1046.00000000', 'locked': '0.00000000'}, {'asset': 'MANA', 'free': '1677.00000000', 'locked': '0.00000000'}, {'asset': 'ADX', 'free': '5111.00000000', 'locked': '0.00000000'}, {'asset': 'ADA', 'free': '734.00000000', 'locked': '0.00000000'}, {'asset': 'XLM', 'free': '1910.00000000', 'locked': '0.00000000'}, {'asset': 'ICX', 'free': '5216.00000000', 'locked': '0.00000000'}, {'asset': 'RLC', 'free': '455.00000000', 'locked': '0.00000000'}, {'asset': 'PIVX', 'free': '3045.00000000', 'locked': '0.00000000'}, {'asset': 'STEEM', 'free': '3586.00000000', 'locked': '0.00000000'}, {'asset': 'ZIL', 'free': '18446.00000000', 'locked': '0.00000000'}, {'asset': 'ONT', 'free': '3556.00000000', 'locked': '0.00000000'}, {'asset': 'WAN', 'free': '4524.00000000', 'locked': '0.00000000'}, {'asset': 'SYS', 'free': '10071.00000000', 'locked': '0.00000000'}, {'asset': 'TUSD', 'free': '10000.00000000', 'locked': '0.00000000'}, {'asset': 'ZEN', 'free': '59.00000000', 'locked': '0.00000000'}, {'asset': 'THETA', 'free': '695.00000000', 'locked': '0.00000000'}, {'asset': 'IOTX', 'free': '18446.00000000', 'locked
....

[carlosmiei]

@kaqsam7 also if you debug the call, you can see the testnet is being used

[kaqsam7]

@carlosmiei Thanks for looking into this so quickly and for the debug screeenshot. It clarified everything!

my python-binance,

Name: python-binance
Version: 1.0.29

Your screenshot shows that the testnet=True flag is using the actual testnet url at a lower level than what client.API_URL is showing me. It explains why my client.get_account() calls were still working even though my logs showed the live URL.

I tried again and the client.API_URL still shows https://api.binance.com/api (the live URL) when i call

# Initialize client 
self.client = Client(config.API_KEY, config.API_SECRET, testnet=config.USE_TESTNET)
logger.debug(f"Client object created: Initial API_URL={self.client.API_URL}, testnet_flag_passed={self.client.testnet}")

# --- Manual Override  --- #
expected_testnet_url = 'https://testnet.binance.vision/api'
if config.USE_TESTNET and self.client.API_URL != expected_testnet_url:
    logger.warning(f"Initial API_URL ({self.client.API_URL}) not expected Testnet URL ({expected_testnet_url})  testnet=True. Manually overriding API_URL.")
    self.client.API_URL = expected_testnet_url

My logs confirmed:

2025-05-22 06:03:01 - binance_api_manager - DEBUG - Client object created: Initial API_URL=https://api.binance.com/api, testnet_flag_passed=True
2025-05-22 06:03:01 - binance_api_manager - WARNING - Initial API_URL (https://api.binance.com/api) not expected Testnet URL (https://testnet.binance.vision/api) testnet=True. Manually overriding API_URL.

It looks like the client.API_URL might not always reflect the true endpoint being used when testnet=True is active, or maybe something in my configuration is causing this. I'm not too sure anymore.

Thanks for clarifying the internal behaviour!

[pcriadoperez]

Hi @kaqsam7.

If it helps to clarify we don't override client.API_URL, depending on the testnet value we use API_URL or TESTNET_API_URL

I'll close this issue for now but feel free to reach out with any other questions