diff --git a/contrib/devtools/update-chainparams.py b/contrib/devtools/update-chainparams.py
new file mode 100755
--- /dev/null
+++ b/contrib/devtools/update-chainparams.py
@@ -0,0 +1,89 @@
+#!/usr/bin/env python3
+# Copyright (c) 2019 The Bitcoin developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+import argparse
+import json
+import subprocess
+import re
+
+parser = argparse.ArgumentParser(description=(
+    "Fetch a block from the bitcoin HTTP RPC to update chainparams"
+    "(nMinimumChainWork and defaultAssumeValid).\n\n"
+    "NOTE: bitcoind must have `--rest=1` set (either as a cli argument or in"
+    "the config)!"), formatter_class=argparse.RawTextHelpFormatter)
+parser.add_argument('--hostaddr', '-a',
+                    default="localhost",
+                    help="Host address of the HTTP RPC bitcoind server to call"
+                         "for fetching chain info. (defaults to `localhost`)")
+parser.add_argument('--hostport', '-p', default="8332",
+                    help="Host port of the HTTP RPC bitcoind server to call"
+                         "for fetching chain info. (defaults to 8332)")
+parser.add_argument('--testnet', '-t', action="store_true",
+                    help="If set, testnet chainparams will be updated instead"
+                         "of mainnet chainparams. If testnet is set, but hostport is not set, hostport will default to 18332.")
+parser.add_argument('--blockhash', '-b',
+                    help="(optional) The block hash to update chainparams"
+                         "with. If not specified, bestblockhash is used.")
+args = parser.parse_args()
+
+
+def curl(url):
+    # Call bitcoin HTTP RPC using curl
+    print("Fetching URL: {}".format(url))
+    curlArgs = ['curl', '-s', url]
+    p = subprocess.Popen('curl -s ' + url, stdout=subprocess.PIPE, shell=True)
+    (output, err) = p.communicate()
+    status = p.wait()
+    if status != 0:
+        print("curl error status: {}\nSee https://curl.haxx.se/libcurl/c/libcurl-errors.html for error descriptions.".format(status))
+        exit(1)
+    return json.loads(output.decode('utf-8'))
+
+
+port = args.hostport
+if args.testnet and port == '8332':
+    port = '18332'
+url = args.hostaddr + ':' + port
+
+# Get best block hash and chainwork
+chaininfo = curl(url + '/rest/chaininfo.json')
+
+chainTestnet = chaininfo['chain'] == 'test'
+if args.testnet != chainTestnet:
+    print("The chain network specified did not match the one given by the host node!")
+    print("Did you mean to call with a different `--hostaddr` or `--hostport`, or with `--testnet` set?")
+    exit(1)
+
+blockhash = chaininfo['bestblockhash']
+chainwork = chaininfo['chainwork']
+if args.blockhash:
+    blockhash = args.blockhash
+    print("Fetching chainwork for block {}".format(blockhash))
+    block = curl(url + '/rest/block/' + blockhash + '.json')
+    chainwork = block['chainwork']
+
+chainParamsClass = 'MainParams'
+if args.testnet:
+    chainParamsClass = 'TestNetParams'
+
+# Get top-level path for the project
+p = subprocess.Popen('git rev-parse --show-toplevel',
+                     stdout=subprocess.PIPE, shell=True)
+(toplevel, err) = p.communicate()
+p.wait()
+
+# Read-write to chainparams.cpp
+f = open(toplevel.decode('utf-8').rstrip() + '/src/chainparams.cpp', 'r+')
+chainParamsContents = f.read()
+
+# Replace chainparams with the new values for the specified chainparams class
+chainParamsContents = re.sub('(' + chainParamsClass + '.*?nMinimumChainWork.*?")(\w+)("\);)',
+                             '\g<1>' + chainwork + '\g<3>', chainParamsContents, flags=re.MULTILINE | re.DOTALL)
+chainParamsContents = re.sub('(' + chainParamsClass + '.*?defaultAssumeValid.*?")(\w+)("\);)',
+                             '\g<1>' + blockhash + '\g<3>', chainParamsContents, flags=re.MULTILINE | re.DOTALL)
+
+f.seek(0)
+f.write(chainParamsContents)
+f.close()