diff --git a/CHANGELOG.md b/CHANGELOG.md
index b1c1366..47db691 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,7 @@
 # Change Log
 
+* compressed OTA updates via [esp32-flashz](https://github.com/vortigont/esp32-flashz) lib
+* web application manifest added, ESPEM webpage could be added as a shortcut on mobile chrome
 * adopted building with Arduino core >2.0.0
 * UI now can detect if PZEM is disconnected or unreachable and show "err" values
 + energy offset feature
diff --git a/espem/espem.cpp b/espem/espem.cpp
index a9dcd4f..29a5859 100644
--- a/espem/espem.cpp
+++ b/espem/espem.cpp
@@ -24,6 +24,8 @@ static const char PGdatajsontpl[] PROGMEM = "{\"age\":%llu,\"U\":%.1f,\"I\":%.2f
 static const char PROGMEM PGsmpld[] = "Metrics collector disabled";
 static const char PROGMEM PGdre[] = "Data read error";
 static const char PROGMEM PGacao[] = "Access-Control-Allow-Origin";
+static const char* PGmimetxt = "text/plain";
+//static const char* PGmimehtml = "text/html; charset=utf-8";
 
 using namespace pzmbus;     // use general pzem abstractions
 
@@ -109,12 +111,12 @@ String& ESPEM::mktxtdata ( String& txtdata) {
 // compat method for v 1.x cacti scripts
 void ESPEM::wpmdata(AsyncWebServerRequest *request) {
   if ( !tsc.getTScnt() ) {
-    request->send(503, FPSTR(PGmimetxt), FPSTR(PGdre) );
+    request->send(503, PGmimetxt, FPSTR(PGdre) );
     return;
   }
 
   String data;
-  request->send(200, FPSTR(PGmimetxt), mktxtdata(data) );
+  request->send(200, PGmimetxt, mktxtdata(data) );
 }
 
 
diff --git a/platformio.ini b/platformio.ini
index a09e609..ebd61df 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -8,7 +8,7 @@ extra_configs =
 [common]
 board_build.filesystem = littlefs
 framework = arduino
-src_build_flags =
+build_src_flags =
   !python flags.py
   -std=gnu++14
   -DUSE_FTP
@@ -50,9 +50,8 @@ platform = espressif32
 board = wemos_d1_mini32
 upload_speed = 460800
 monitor_filters = esp32_exception_decoder
-;build_flags =
-;  -DTZONE="MSK-3"
-;  -DCOUNTRY="ru"
+build_flags =
+  -DCOUNTRY="ru"
 lib_ignore =
   ESPAsyncTCP
   LITTLEFS
@@ -87,8 +86,8 @@ lib_deps =
 build_flags =
   ${esp32_base.build_flags}
   -DCOUNTRY="ru"
-;src_build_flags =
-;  ${common.src_build_flags}
+;build_src_flags =
+;  ${common.build_src_flags}
 ;src_build_unflags =
 ;  ${common.src_build_unflags}
 
@@ -125,3 +124,10 @@ build_flags =
   -DCOUNTRY="ru"
 lib_ignore =
     ESPAsyncTCP
+
+; Over-the-air compressed update
+; copy this template into user_ota.ini file and replace URL with your device adddress
+;[espem_ota]
+;extra_scripts = post_flashz.py
+;OTA_URL = http://espem/update
+;OTA_compress = true
\ No newline at end of file
diff --git a/post_flashz.py b/post_flashz.py
new file mode 100644
index 0000000..a94646a
--- /dev/null
+++ b/post_flashz.py
@@ -0,0 +1,96 @@
+#!/usr/bin/python
+
+#https://docs.platformio.org/en/latest/scripting/actions.html
+#https://trass3r.github.io/coding/2018/12/20/advanced-platformio.html
+#https://github.com/platformio/bintray-secure-ota/blob/master/publish_firmware.py
+
+from os.path import basename
+from os.path import isfile
+from os.path import getsize
+
+import subprocess
+import requests
+import sys,zlib
+import re
+
+Import("env", "projenv")
+
+# access to global build environment
+#print(env)
+
+# access to project build environment (is used source files in "src" folder)
+#print(projenv.Dump())
+
+#
+# Dump build environment (for debug purpose)
+# print(env.Dump())
+#
+
+
+def pigz_compress(source, target, env):
+    firmware_path = str(target[0])      #.replace(".elf", ".bin")
+    #firmware_name = basename(firmware_path)
+    print("Compressing %s file..." % basename(firmware_path))
+    subprocess.run(["pigz", "-fzk11", firmware_path])
+
+#def zlib_compress(source, target, env):
+def zlib_compress(source):
+    imgfile = source
+    print("Compressing %s file..." % basename(imgfile))
+    with open(imgfile, 'rb') as img:
+            with open(imgfile + '.zz', 'wb') as deflated:
+                data = zlib.compress(img.read(), zlib.Z_BEST_COMPRESSION)
+                deflated.write(data)
+                compress_ratio = (float(getsize(imgfile)) - float(getsize(imgfile + '.zz'))) / float(getsize(imgfile)) * 100
+                print("Compress ratio %d%%" % compress_ratio)
+
+def ota_upload(source, target, env):
+    file_path = str(source[0])
+    print ("Found OTA_url option, will attempt over-the-air upload")
+
+    try:
+        compress = env.GetProjectOption('OTA_compress')
+        if compress in ("yes", "true", "1"):
+            print("Found OTA_compress option")
+            zlib_compress(file_path)
+            if (isfile(file_path + ".zz")):
+                file_path += ".zz"
+    except:
+        print ("OTA_compress not found, NOT using compression")
+
+
+    url = env.GetProjectOption('OTA_url')
+
+    # check if we upload a firmware or FS image
+    imgtype = None
+    if (bool(re.search('firmware', file_path))):
+        imgtype = 'fw'
+    else:
+        imgtype = 'fs'
+
+    payload = {'img' : imgtype }
+    f = {'file': open(file_path, 'rb')}
+    req = None
+    try:
+        print("Uploading file %s to %s " % (file_path, url))
+        req = requests.post(url, data = payload, files=f)
+        req.raise_for_status()
+    except requests.exceptions.RequestException as e:
+        sys.stderr.write("Failed to upload file: %s\n" %
+                         ("%s\n%s" % (req.status_code, req.text) if req else str(e)))
+        env.Exit(1)
+
+    print("The firmware has been successfuly uploaded!")
+
+# available targets, i.e. buildprog, size, upload, program, buildfs, uploadfs, uploadfsota
+#buildprog is a target when ALL files are compiled and PROGRAM is ready.
+
+# autocompress all bin images (fw and fs)
+#env.AddPostAction("$BUILD_DIR/${PROGNAME}.bin", pigz_compress)
+
+# Custom upload handler
+try:
+    env.GetProjectOption('OTA_url')
+    env.Replace(UPLOADCMD=ota_upload)
+except:
+    print ("OTA_url not found, fallback to serial flasher")