diff --git a/src/sysvars.hpp b/src/sysvars.hpp
new file mode 100644
index 0000000..ae2b563
--- /dev/null
+++ b/src/sysvars.hpp
@@ -0,0 +1,156 @@
+#ifndef _SYSVARS_H_
+#define _SYSVARS_H_
+// Key-Value JSON file store unit
+// Ma za ukol ukladat/nacitat pary key-value do/z JSON
+
+#include <Arduino.h>
+#include <ArduinoJson.h>
+#include <FS.h>
+#ifndef USEDFS
+# if defined(ESP32)
+#  ifdef USE_LITTLEFS
+#   include <LITTLEFS.h>
+#   define USEDFS LITTLEFS
+#  else
+#   include <SPIFFS.h>
+#   define USEDFS SPIFFS
+#  endif
+# else
+#  include <LittleFS.h>
+#  define USEDFS LittleFS
+# endif
+#endif
+
+enum {
+    SV_OK = 0,
+    SV_UNSPECIFIED_ERROR = -1,
+    SV_FILE_NOT_FOUND = -2,
+    SV_DESERIALIZE_ERROR = -3,
+    SV_WRONG_DATA_TYPE = -4,
+    SV_FILE_WRITE_ERROR = -5,
+    SV_KEY_NOT_FOUND = -6,
+};
+
+#if not defined(SYSVAR_FILE)
+# define SYSVAR_FILE "/cfg.json"
+#endif
+
+#if not defined(SYSVAR_DOCUMENT_SIZE)
+# define SYSVAR_DOCUMENT_SIZE (4096)
+#endif
+
+template <typename T>
+T svGetV(const String& name, int* result = nullptr)
+{
+    T retval{};
+    int res = SV_UNSPECIFIED_ERROR; // predpokladame chybu
+    DynamicJsonDocument doc(SYSVAR_DOCUMENT_SIZE);
+    File f;
+
+    f = USEDFS.open(F(SYSVAR_FILE), "r");
+    if (f) {
+        DeserializationError err = deserializeJson(doc, f);
+        if (err) {
+            res = SV_DESERIALIZE_ERROR; // spatny JSON soubor
+        } else {
+            if (!doc.containsKey(name))
+            {
+                res = SV_KEY_NOT_FOUND; // chyba - nenalezeny klic
+            } else {
+                retval = doc[name].as<T>();
+                res = SV_OK;
+            }
+        }
+    } else {
+        res = SV_FILE_NOT_FOUND; // chyba - nenalezeny soubor
+    }
+    if (result)
+        *result = res; // navratovy kod, pokud nas zajima
+    return retval;
+}
+
+template <typename T>
+T svGetV(const String& name, int* result, const String& fname)
+{
+    T retval{};
+    int res = SV_UNSPECIFIED_ERROR; // predpokladame chybu
+    DynamicJsonDocument doc(SYSVAR_DOCUMENT_SIZE);
+    File f;
+
+    f = USEDFS.open(fname, "r");
+    if (f) {
+        DeserializationError err = deserializeJson(doc, f);
+        if (err) {
+            res = SV_DESERIALIZE_ERROR; // spatny JSON soubor
+        } else {
+            if (!doc.containsKey(name))
+            {
+                res = SV_KEY_NOT_FOUND; // chyba - nenalezeny klic
+            } else {
+                retval = doc[name].as<T>();
+                res = SV_OK;
+            }
+        }
+    } else {
+        res = SV_FILE_NOT_FOUND; // chyba - nenalezeny soubor
+    }
+    if (result)
+        *result = res; // navratovy kod, pokud nas zajima
+    return retval;
+}
+
+template <typename T>
+int svSetV(const String& name, T value)
+{
+    int res = SV_UNSPECIFIED_ERROR;
+    DynamicJsonDocument doc(SYSVAR_DOCUMENT_SIZE);
+    File f;
+
+    f = USEDFS.open(F(SYSVAR_FILE), "r");
+    if (f) {
+        DeserializationError err = deserializeJson(doc, f);
+        if (err) {
+            res = SV_DESERIALIZE_ERROR; // spatny JSON soubor
+        }
+        f.close();
+    }
+    doc[name] = value;
+
+    f = USEDFS.open(SYSVAR_FILE, "w");
+    if (f) {
+        serializeJson(doc, f);
+        res = SV_OK;
+    } else {
+        res = SV_FILE_WRITE_ERROR;
+    }
+    return res;
+}
+
+template <typename T>
+int svSetV(const String& name, T value, const String& fname)
+{
+    int res = SV_UNSPECIFIED_ERROR;
+    DynamicJsonDocument doc(SYSVAR_DOCUMENT_SIZE);
+    File f;
+
+    f = USEDFS.open(fname, "r");
+    if (f) {
+        DeserializationError err = deserializeJson(doc, f);
+        if (err) {
+            res = SV_DESERIALIZE_ERROR; // spatny JSON soubor
+        }
+        f.close();
+    }
+    doc[name] = value;
+
+    f = USEDFS.open(fname, "w");
+    if (f) {
+        serializeJson(doc, f);
+        res = SV_OK;
+    } else {
+        res = SV_FILE_WRITE_ERROR;
+    }
+
+    return res;
+}
+#endif