diff --git a/data/helpers.d/system b/data/helpers.d/system
index 70cc57493..63b90ef13 100644
--- a/data/helpers.d/system
+++ b/data/helpers.d/system
@@ -53,3 +53,108 @@ ynh_abort_if_errors () {
 ynh_get_debian_release () {
 	echo $(lsb_release --codename --short)
 }
+
+# Read the value of a key in a ynh manifest file
+#
+# usage: ynh_read_manifest manifest key
+# | arg: -m, --manifest= - Path of the manifest to read
+# | arg: -k, --key= - Name of the key to find
+ynh_read_manifest () {
+	# Declare an array to define the options of this helper.
+        declare -Ar args_array=( [m]=manifest= [k]=manifest_key= )
+        local manifest
+        local manifest_key
+	# Manage arguments with getopts
+	ynh_handle_getopts_args "$@"
+
+	python3 -c "import sys, json;print(json.load(open('$manifest', encoding='utf-8'))['$manifest_key'])"
+}
+
+# Read the upstream version from the manifest
+# The version number in the manifest is defined by <upstreamversion>~ynh<packageversion>
+# For example : 4.3-2~ynh3
+# This include the number before ~ynh
+# In the last example it return 4.3-2
+#
+# usage: ynh_app_upstream_version [-m manifest]
+# | arg: -m, --manifest= - Path of the manifest to read
+ynh_app_upstream_version () {
+    declare -Ar args_array=( [m]=manifest= )
+    local manifest
+    # Manage arguments with getopts
+    ynh_handle_getopts_args "$@"
+
+    manifest="${manifest:-../manifest.json}"
+    if [ ! -e "$manifest_path" ]; then
+        manifest_path="../settings/manifest.json"	# Into the restore script, the manifest is not at the same place
+    fi
+    version_key=$(ynh_read_manifest --manifest="$manifest_path" --manifest_key="version")
+    echo "${version_key/~ynh*/}"
+}
+
+# Read package version from the manifest
+# The version number in the manifest is defined by <upstreamversion>~ynh<packageversion>
+# For example : 4.3-2~ynh3
+# This include the number after ~ynh
+# In the last example it return 3
+#
+# usage: ynh_app_package_version [-m manifest]
+# | arg: -m, --manifest= - Path of the manifest to read
+ynh_app_package_version () {
+    declare -Ar args_array=( [m]=manifest= )
+    local manifest
+    # Manage arguments with getopts
+    ynh_handle_getopts_args "$@"
+
+    manifest="${manifest:-../manifest.json}"
+    if [ ! -e "$manifest_path" ]; then
+        manifest_path="../settings/manifest.json"	# Into the restore script, the manifest is not at the same place
+    fi
+    version_key=$(ynh_read_manifest --manifest="$manifest_path" --manifest_key="version")
+    echo "${version_key/*~ynh/}"
+}
+
+# Checks the app version to upgrade with the existing app version and returns:
+# - UPGRADE_APP if the upstream app version has changed
+# - UPGRADE_PACKAGE if only the YunoHost package has changed
+#
+## It stops the current script without error if the package is up-to-date
+#
+# This helper should be used to avoid an upgrade of an app, or the upstream part
+# of it, when it's not needed
+#
+# To force an upgrade, even if the package is up to date,
+# you have to set the variable YNH_FORCE_UPGRADE before.
+# example: sudo YNH_FORCE_UPGRADE=1 yunohost app upgrade MyApp
+
+# usage: ynh_check_app_version_changed
+ynh_check_app_version_changed () {
+  local force_upgrade=${YNH_FORCE_UPGRADE:-0}
+  local package_check=${PACKAGE_CHECK_EXEC:-0}
+
+  # By default, upstream app version has changed
+  local return_value="UPGRADE_APP"
+
+  local current_version=$(ynh_read_manifest --manifest="/etc/yunohost/apps/$YNH_APP_INSTANCE_NAME/manifest.json" --manifest_key="version" || echo 1.0)
+  local current_upstream_version="$(ynh_app_upstream_version --manifest="/etc/yunohost/apps/$YNH_APP_INSTANCE_NAME/manifest.json")"
+  local update_version=$(ynh_read_manifest --manifest="../manifest.json" --manifest_key="version" || echo 1.0)
+  local update_upstream_version="$(ynh_app_upstream_version)"
+
+  if [ "$current_version" == "$update_version" ] ; then
+      # Complete versions are the same
+      if [ "$force_upgrade" != "0" ]
+      then
+        echo "Upgrade forced by YNH_FORCE_UPGRADE." >&2
+        unset YNH_FORCE_UPGRADE
+      elif [ "$package_check" != "0" ]
+      then
+        echo "Upgrade forced for package check." >&2
+      else
+        ynh_die "Up-to-date, nothing to do" 0
+      fi
+  elif [ "$current_upstream_version" == "$update_upstream_version" ] ; then
+    # Upstream versions are the same, only YunoHost package versions differ
+    return_value="UPGRADE_PACKAGE"
+  fi
+  echo $return_value
+}