diff --git a/.gitignore b/.gitignore
index 189944ab9e..4b1dccf38a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -120,3 +120,4 @@ src/smc-webapp/_colors.sass
 
 # pytest cache
 src/smc_sagews/.pytest_cache/
+.mypy_cache/
diff --git a/src/package.json b/src/package.json
index c072ee5d00..9aa93cd8a4 100644
--- a/src/package.json
+++ b/src/package.json
@@ -92,7 +92,7 @@
     "lint": "node_modules/.bin/coffeelint -f smc-util/coffeelint.json -c *.coffee && cd smc-hub && npm run lint && cd ../smc-webapp && npm run lint && cd ../smc-util && npm run lint && cd ../smc-util-node && npm run lint",
     "test": "export SMC_TEST=true&& cd smc-util && npm test && cd ../smc-util-node && npm test && cd ../smc-hub && npm test && cd ../smc-webapp && npm test && cd ../smc-project && npm test",
     "coverage": "cd smc-util && npm run coverage && cd ../smc-util-node && npm run coverage && cd ../smc-hub && npm run coverage && cd ../smc-webapp && npm run coverage",
-    "webpack-watch": "cd $SALVUS_ROOT; scripts/update_color_scheme.coffee; webapp-lib/primus/update_primus; unset CC_STATICPAGES; CC_NOCLEAN=true SOURCE_MAP=true NODE_ENV=development node --max_old_space_size=8192 node_modules/webpack/bin/webpack.js --debug --output-pathinfo --progress --colors --watch --watch-poll=1000",
+    "webpack-watch": "cd $SALVUS_ROOT; scripts/check_npm_packages.py; scripts/update_color_scheme.coffee; webapp-lib/primus/update_primus; unset CC_STATICPAGES; CC_NOCLEAN=true SOURCE_MAP=true NODE_ENV=development node --max_old_space_size=8192 node_modules/webpack/bin/webpack.js --debug --output-pathinfo --progress --colors --watch --watch-poll=1000",
     "webpack-debug": "cd $SALVUS_ROOT; scripts/update_color_scheme.coffee; webapp-lib/primus/update_primus; SOURCE_MAP=true NODE_ENV=development webpack --debug --progress --colors",
     "webpack-production": "cd $SALVUS_ROOT; scripts/update_color_scheme.coffee; webapp-lib/primus/update_primus; NODE_ENV=production node --max_old_space_size=8192 node_modules/webpack/bin/webpack.js --progress --colors",
     "webpack-clean": "rm -rvf $SALVUS_ROOT/static/",
diff --git a/src/scripts/check_npm_packages.py b/src/scripts/check_npm_packages.py
new file mode 100755
index 0000000000..0ffe1dde77
--- /dev/null
+++ b/src/scripts/check_npm_packages.py
@@ -0,0 +1,85 @@
+#!/usr/bin/env python3
+"""
+Consistency check for npm packages across node modules
+
+Hint: to get a "real time" info while working on resolving this, run
+      $ /usr/bin/watch -n1 check_npm_packages.py
+      in the SMC_ROOT dir in a separate terminal.
+"""
+
+import os
+from os.path import abspath, dirname, basename
+import json
+from collections import defaultdict
+from pprint import pprint
+from subprocess import run, PIPE
+from typing import List, Set, Dict, Tuple, Optional
+from typing_extensions import Final
+
+T_installs = Dict[str, Dict[str, str]]
+
+root: Final[str] = os.environ.get('SMC_ROOT', abspath(os.curdir))
+
+
+def pkg_dirs() -> List[str]:
+    search = run(['git', 'ls-files', '--', '../**/package.json'], stdout=PIPE)
+    data = search.stdout.decode('utf8')
+    packages = [abspath(_) for _ in data.splitlines()]
+    return packages
+
+
+def get_versions(packages, dep_type) -> Tuple[T_installs, Set[str]]:
+    installs: T_installs = defaultdict(dict)
+    modules: Set[str] = set()
+
+    for pkg in packages:
+        pkgs = json.load(open(pkg))
+        module = basename(dirname(pkg))
+        modules.add(module)
+        for name, vers in pkgs.get(dep_type, {}).items():
+            installs[name][module] = vers
+    return installs, modules
+
+
+def print_table(installs: T_installs, modules) -> Tuple[str, int]:
+    cnt = 0
+    table = ""
+
+    table += f"{'':<30s}"
+    for mod in sorted(modules):
+        table += f"{mod:<15s}"
+    table += "\n"
+
+    for pkg, inst in sorted(installs.items()):
+        if len(set(inst.values())) == 1: continue
+        cnt += 1
+        table += f"{pkg:<30s}"
+        for mod in sorted(modules):
+            vers = inst.get(mod, '')
+            table += f"{vers:<15s}"
+        table += "\n"
+    return table, cnt
+
+
+def main() -> None:
+    packages: Final = pkg_dirs()
+
+    main_pkgs, main_mods = get_versions(packages, 'dependencies')
+    dev_pkgs, dev_mods = get_versions(packages, 'devDependencies')
+
+    dev_table, dev_incon = print_table(dev_pkgs, dev_mods)
+    if dev_incon > 0:
+        print("Development Modules")
+        print(dev_table)
+        print("\nRegular Code Modules")
+
+    table, incons = print_table(main_pkgs, main_mods)
+
+    if incons > 0:
+        print(table)
+        print(f"\nThere are {incons} inconsistencies")
+        exit(1)
+
+
+if __name__ == '__main__':
+    main()