diff --git a/contrib/addr.py b/contrib/addr.py
index 326b900..da36c56 100755
--- a/contrib/addr.py
+++ b/contrib/addr.py
@@ -20,7 +20,7 @@ def main():
         Network = BitcoinMainnet
         port = 50001
 
-    conn = client.Connection(('localhost', port))
+    conn = client.Client(('localhost', port))
     for addr in args.address:
         script = Network.ui.script_for_address(addr)
         script_hash = hashlib.sha256(script).digest()[::-1].hex()
diff --git a/contrib/client.py b/contrib/client.py
index d47a921..17ce913 100644
--- a/contrib/client.py
+++ b/contrib/client.py
@@ -1,7 +1,7 @@
 import json
 import socket
 
-class Connection:
+class Client:
     def __init__(self, addr):
         self.s = socket.create_connection(addr)
         self.f = self.s.makefile('r')
diff --git a/contrib/daemon.py b/contrib/daemon.py
new file mode 100644
index 0000000..85c7351
--- /dev/null
+++ b/contrib/daemon.py
@@ -0,0 +1,41 @@
+import binascii
+import json
+import os
+import socket
+
+
+class Daemon:
+    def __init__(self, port, cookie_dir):
+        self.sock = socket.create_connection(('localhost', port))
+        self.fd = self.sock.makefile()
+        path = os.path.join(os.path.expanduser(cookie_dir), '.cookie')
+        cookie = binascii.b2a_base64(open(path, 'rb').read())
+        self.cookie = cookie.decode('ascii').strip()
+        self.index = 0
+
+    def request(self, method, params_list):
+        obj = [{"method": method, "params": params, "id": self.index}
+               for params in params_list]
+        request = json.dumps(obj)
+
+        msg = ('POST / HTTP/1.1\n'
+               'Authorization: Basic {}\n'
+               'Content-Length: {}\n\n'
+               '{}'.format(self.cookie, len(request), request))
+        self.sock.sendall(msg.encode('ascii'))
+
+        status = self.fd.readline().strip()
+        while True:
+            if self.fd.readline().strip():
+                continue  # skip headers
+            else:
+                break  # next line will contain the response
+
+        data = self.fd.readline().strip()
+        replies = json.loads(data)
+        for reply in replies:
+            assert reply['error'] is None, reply
+            assert reply['id'] == self.index
+
+        self.index += 1
+        return [d['result'] for d in replies]
diff --git a/contrib/mempool.py b/contrib/mempool.py
index 987aa2a..f5d7486 100755
--- a/contrib/mempool.py
+++ b/contrib/mempool.py
@@ -1,49 +1,11 @@
 #!/usr/bin/env python3
+
 import argparse
-import binascii
-import json
-import os
-import socket
+from daemon import Daemon
 
 import numpy as np
 import matplotlib.pyplot as plt
 
-class Daemon:
-    def __init__(self, port, cookie_dir):
-        self.sock = socket.create_connection(('localhost', port))
-        self.fd = self.sock.makefile()
-        path = os.path.join(os.path.expanduser(cookie_dir), '.cookie')
-        cookie = binascii.b2a_base64(open(path, 'rb').read())
-        self.cookie = cookie.decode('ascii').strip()
-        self.index = 0
-
-    def request(self, method, params_list):
-        obj = [{"method": method, "params": params, "id": self.index}
-               for params in params_list]
-        request = json.dumps(obj)
-
-        msg = ('POST / HTTP/1.1\n'
-               'Authorization: Basic {}\n'
-               'Content-Length: {}\n\n'
-               '{}'.format(self.cookie, len(request), request))
-        self.sock.sendall(msg.encode('ascii'))
-
-        status = self.fd.readline().strip()
-        while True:
-            if self.fd.readline().strip():
-                continue  # skip headers
-            else:
-                break  # next line will contain the response
-
-        data = self.fd.readline().strip()
-        replies = json.loads(data)
-        for reply in replies:
-            assert reply['error'] is None
-            assert reply['id'] == self.index
-
-        self.index += 1
-        return [d['result'] for d in replies]
-
 
 def main():
     parser = argparse.ArgumentParser()
diff --git a/contrib/tx_fee.py b/contrib/tx_fee.py
new file mode 100755
index 0000000..7af4b22
--- /dev/null
+++ b/contrib/tx_fee.py
@@ -0,0 +1,33 @@
+#!/usr/bin/env python3
+import argparse
+import daemon
+
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument('txid')
+    args = parser.parse_args()
+
+    d = daemon.Daemon(port=8332, cookie_dir='~/.bitcoin')
+    txid = args.txid
+
+    txn, = d.request('getrawtransaction', [[txid, True]])
+    vin = txn['vin']
+
+    fee = 0.0
+    for txi in txn['vin']:
+        prev_txid = txi['txid']
+        prev_tx, = d.request('getrawtransaction', [[prev_txid, True]])
+        index = txi['vout']
+        prev_txo = prev_tx['vout'][index]
+        print(f"{prev_txid}:{index:<5} {prev_txo['value']:+20.8f}")
+        fee += prev_txo['value']
+
+    for i, txo in enumerate(txn['vout']):
+        print(f"{txid}:{i:<5} {-txo['value']:+20.8f}")
+        fee -= txo['value']
+
+    print(f"Fee = {1e6 * fee:.2f} uBTC = {1e8 * fee / txn['vsize']:.2f} sat/vB")
+
+if __name__ == '__main__':
+    main()
diff --git a/contrib/xpub.py b/contrib/xpub.py
index cfab863..4ed6e19 100755
--- a/contrib/xpub.py
+++ b/contrib/xpub.py
@@ -15,7 +15,7 @@ script_for_address = BitcoinMainnet.ui.script_for_address
 log = Logger(__name__)
 
 def main():
-    conn = client.Connection(('localhost', 50001))
+    conn = client.Client(('localhost', 50001))
     xpub, = sys.argv[1:]
     total = 0
     k = pycoin.ui.key_from_text.key_from_text(xpub)