diff --git a/copyparty/httpcli.py b/copyparty/httpcli.py
index 8953059f..b50599c6 100644
--- a/copyparty/httpcli.py
+++ b/copyparty/httpcli.py
@@ -72,9 +72,13 @@ class HttpCli(object):
         if rem.startswith("/") or rem.startswith("../") or "/../" in rem:
             raise Exception("that was close")
 
-    def j2(self, name, **kwargs):
+    def j2(self, name, **ka):
         tpl = self.conn.hsrv.j2[name]
-        return tpl.render(**kwargs) if kwargs else tpl
+        if ka:
+            ka["ts"] = self.conn.hsrv.cachebuster()
+            return tpl.render(**ka)
+
+        return tpl
 
     def run(self):
         """returns true if connection can be reused"""
@@ -1383,6 +1387,7 @@ class HttpCli(object):
             "md_plug": "true" if self.args.emp else "false",
             "md_chk_rate": self.args.mcr,
             "md": boundary,
+            "ts": self.conn.hsrv.cachebuster(),
         }
         html = template.render(**targs).encode("utf-8", "replace")
         html = html.split(boundary.encode("utf-8"))
@@ -1626,7 +1631,6 @@ class HttpCli(object):
 
         url_suf = self.urlq()
         is_ls = "ls" in self.uparam
-        ts = ""  # "?{}".format(time.time())
 
         tpl = "browser"
         if "b" in self.uparam:
@@ -1651,7 +1655,6 @@ class HttpCli(object):
             "vdir": quotep(self.vpath),
             "vpnodes": vpnodes,
             "files": [],
-            "ts": ts,
             "perms": json.dumps(perms),
             "taglist": [],
             "tag_order": [],
diff --git a/copyparty/httpsrv.py b/copyparty/httpsrv.py
index b0e13d0c..8bb5d0ed 100644
--- a/copyparty/httpsrv.py
+++ b/copyparty/httpsrv.py
@@ -4,6 +4,8 @@ from __future__ import print_function, unicode_literals
 import os
 import sys
 import time
+import base64
+import struct
 import socket
 import threading
 
@@ -25,7 +27,6 @@ except ImportError:
     sys.exit(1)
 
 from .__init__ import E, MACOS
-from .authsrv import AuthSrv
 from .httpconn import HttpConn
 
 
@@ -48,6 +49,8 @@ class HttpSrv(object):
         self.clients = {}
         self.workload = 0
         self.workload_thr_alive = False
+        self.cb_ts = 0
+        self.cb_v = 0
 
         env = jinja2.Environment()
         env.loader = jinja2.FileSystemLoader(os.path.join(E.mod, "web"))
@@ -177,3 +180,25 @@ class HttpSrv(object):
                     self.clients[cli] = now
 
             self.workload = total
+
+    def cachebuster(self):
+        if time.time() - self.cb_ts < 1:
+            return self.cb_v
+
+        with self.mutex:
+            if time.time() - self.cb_ts < 1:
+                return self.cb_v
+
+            v = E.t0
+            try:
+                with os.scandir(os.path.join(E.mod, "web")) as dh:
+                    for fh in dh:
+                        inf = fh.stat(follow_symlinks=False)
+                        v = max(v, inf.st_mtime)
+            except:
+                pass
+
+            v = base64.urlsafe_b64encode(struct.pack(">xxL", int(v)))
+            self.cb_v = v.decode("ascii")[-4:]
+            self.cb_ts = time.time()
+            return self.cb_v
diff --git a/copyparty/web/browser.html b/copyparty/web/browser.html
index 8280420f..0a0b4b30 100644
--- a/copyparty/web/browser.html
+++ b/copyparty/web/browser.html
@@ -6,10 +6,10 @@
 	<title>⇆🎉 {{ title }}</title>
 	<meta http-equiv="X-UA-Compatible" content="IE=edge">
 	<meta name="viewport" content="width=device-width, initial-scale=0.8">
-	<link rel="stylesheet" type="text/css" media="screen" href="/.cpr/browser.css{{ ts }}">
-	<link rel="stylesheet" type="text/css" media="screen" href="/.cpr/upload.css{{ ts }}">
+	<link rel="stylesheet" type="text/css" media="screen" href="/.cpr/browser.css?_={{ ts }}">
+	<link rel="stylesheet" type="text/css" media="screen" href="/.cpr/upload.css?_={{ ts }}">
 	{%- if css %}
-	<link rel="stylesheet" type="text/css" media="screen" href="{{ css }}{{ ts }}">
+	<link rel="stylesheet" type="text/css" media="screen" href="{{ css }}?_={{ ts }}">
 	{%- endif %}
 </head>
 
@@ -127,9 +127,9 @@
 			have_tags_idx = {{ have_tags_idx|tojson }},
 			have_zip = {{ have_zip|tojson }};
 	</script>
-	<script src="/.cpr/util.js{{ ts }}"></script>
-	<script src="/.cpr/browser.js{{ ts }}"></script>
-	<script src="/.cpr/up2k.js{{ ts }}"></script>
+	<script src="/.cpr/util.js?_={{ ts }}"></script>
+	<script src="/.cpr/browser.js?_={{ ts }}"></script>
+	<script src="/.cpr/up2k.js?_={{ ts }}"></script>
 </body>
 
 </html>
diff --git a/copyparty/web/md.html b/copyparty/web/md.html
index 171d0dd8..8dc6a618 100644
--- a/copyparty/web/md.html
+++ b/copyparty/web/md.html
@@ -3,9 +3,9 @@
 	<title>📝🎉 {{ title }}</title> <!-- 📜 -->
 	<meta http-equiv="X-UA-Compatible" content="IE=edge">
 	<meta name="viewport" content="width=device-width, initial-scale=0.7">
-	<link href="/.cpr/md.css" rel="stylesheet">
+	<link href="/.cpr/md.css?_={{ ts }}" rel="stylesheet">
 	{%- if edit %}
-	<link href="/.cpr/md2.css" rel="stylesheet">
+	<link href="/.cpr/md2.css?_={{ ts }}" rel="stylesheet">
 	{%- endif %}
 </head>
 <body>
@@ -146,10 +146,10 @@ var md_opt = {
 })();
 
 	</script>
-    <script src="/.cpr/util.js"></script>
-	<script src="/.cpr/deps/marked.js"></script>
-	<script src="/.cpr/md.js"></script>
+    <script src="/.cpr/util.js?_={{ ts }}"></script>
+	<script src="/.cpr/deps/marked.js?_={{ ts }}"></script>
+	<script src="/.cpr/md.js?_={{ ts }}"></script>
 	{%- if edit %}
-	<script src="/.cpr/md2.js"></script>
+	<script src="/.cpr/md2.js?_={{ ts }}"></script>
 	{%- endif %}
 </body></html>
diff --git a/copyparty/web/mde.html b/copyparty/web/mde.html
index eaf3fa3b..05077288 100644
--- a/copyparty/web/mde.html
+++ b/copyparty/web/mde.html
@@ -3,9 +3,9 @@
 	<title>📝🎉 {{ title }}</title>
 	<meta http-equiv="X-UA-Compatible" content="IE=edge">
 	<meta name="viewport" content="width=device-width, initial-scale=0.7">
-	<link href="/.cpr/mde.css" rel="stylesheet">
-	<link href="/.cpr/deps/mini-fa.css" rel="stylesheet">
-	<link href="/.cpr/deps/easymde.css" rel="stylesheet">
+	<link href="/.cpr/mde.css?_={{ ts }}" rel="stylesheet">
+	<link href="/.cpr/deps/mini-fa.css?_={{ ts }}" rel="stylesheet">
+	<link href="/.cpr/deps/easymde.css?_={{ ts }}" rel="stylesheet">
 </head>
 <body>
 	<div id="mw">
@@ -43,7 +43,7 @@ var lightswitch = (function () {
 })();
 
 	</script>
-    <script src="/.cpr/util.js"></script>
-	<script src="/.cpr/deps/easymde.js"></script>
-	<script src="/.cpr/mde.js"></script>
+    <script src="/.cpr/util.js?_={{ ts }}"></script>
+	<script src="/.cpr/deps/easymde.js?_={{ ts }}"></script>
+	<script src="/.cpr/mde.js?_={{ ts }}"></script>
 </body></html>
diff --git a/copyparty/web/msg.html b/copyparty/web/msg.html
index 5e5e0615..31f0c256 100644
--- a/copyparty/web/msg.html
+++ b/copyparty/web/msg.html
@@ -6,7 +6,7 @@
     <title>copyparty</title>
     <meta http-equiv="X-UA-Compatible" content="IE=edge">
     <meta name="viewport" content="width=device-width, initial-scale=0.8">
-    <link rel="stylesheet" type="text/css" media="screen" href="/.cpr/msg.css">
+    <link rel="stylesheet" type="text/css" media="screen" href="/.cpr/msg.css?_={{ ts }}">
 </head>
 
 <body>
diff --git a/copyparty/web/splash.html b/copyparty/web/splash.html
index 133e2b12..f9b71f1b 100644
--- a/copyparty/web/splash.html
+++ b/copyparty/web/splash.html
@@ -6,7 +6,7 @@
     <title>copyparty</title>
     <meta http-equiv="X-UA-Compatible" content="IE=edge">
     <meta name="viewport" content="width=device-width, initial-scale=0.8">
-    <link rel="stylesheet" type="text/css" media="screen" href="/.cpr/splash.css">
+    <link rel="stylesheet" type="text/css" media="screen" href="/.cpr/splash.css?_={{ ts }}">
 </head>
 
 <body>
diff --git a/tests/util.py b/tests/util.py
index a1536f64..214f49d2 100644
--- a/tests/util.py
+++ b/tests/util.py
@@ -108,6 +108,9 @@ class VHttpSrv(object):
         aliases = ["splash", "browser", "browser2", "msg", "md", "mde"]
         self.j2 = {x: J2_FILES for x in aliases}
 
+    def cachebuster(self):
+        return "a"
+
 
 class VHttpConn(object):
     def __init__(self, args, asrv, log, buf):