diff --git a/constant.py b/constant.py
new file mode 100644
index 0000000..c79737c
--- /dev/null
+++ b/constant.py
@@ -0,0 +1,9 @@
+# web3 provider information
+# include provider HTTPS endpoint URL & its API Key.
+# Alchemy is a good choice for Web3 provider
+WEB3_PROVIDER_URL = "https://eth-sepolia.g.alchemy.com/v2/"
+WEB3_PROVIDER_KEY = ""
+
+# Please write down your wallet key to sign a transaction with our contract.
+WALLET_KEY = ""
+
diff --git a/src/node_manager.py b/src/node_manager.py
index 328e00a..ce9e8ac 100644
--- a/src/node_manager.py
+++ b/src/node_manager.py
@@ -5,6 +5,7 @@ import time
 import docker
 from web3 import Web3
 from src.scheduler import Scheduler
+from constant import *
 
 class NodeManager():
     def __init__(self, host, port):
@@ -28,7 +29,7 @@ class NodeManager():
         self.docker_client = docker.from_env()
 
         # web3 provider
-        self.w3 = Web3(Web3.HTTPProvider('https://eth-sepolia.g.alchemy.com/v2/'+ALCHEMY_KEY))
+        self.w3 = Web3(Web3.HTTPProvider(WEB3_PROVIDER_URL + WEB3_PROVIDER_KEY))
 
         time.sleep(2)