diff --git a/ESPWebThingAdapter.h b/ESPWebThingAdapter.h
index 3ba034a..61cecb3 100644
--- a/ESPWebThingAdapter.h
+++ b/ESPWebThingAdapter.h
@@ -85,10 +85,9 @@ class WebThingAdapter {
 #ifndef WITHOUT_WS
   void sendChangedPropsOrEvents(ThingDevice* device, const char* type, ThingItem* rootItem) {
     // Prepare one buffer per device
-    DynamicJsonBuffer buf(1024);
-    JsonObject& message = buf.createObject();
+    DynamicJsonDocument message(1024);
     message["messageType"] = type;
-    JsonObject& prop = message.createNestedObject("data");
+    JsonObject prop = message.createNestedObject("data");
     bool dataToSend = false;
     ThingItem* item = rootItem;
     while (item != nullptr) {
@@ -101,7 +100,7 @@ class WebThingAdapter {
     }
     if (dataToSend) {
       String jsonStr;
-      message.printTo(jsonStr);
+      serializeJson(message, jsonStr);
       // Inform all connected ws clients of a Thing about changed properties
       ((AsyncWebSocket*)device->ws)->textAll(jsonStr.c_str(), jsonStr.length());
     }
@@ -173,12 +172,11 @@ class WebThingAdapter {
   }
 
   #ifndef WITHOUT_WS
-  void sendErrorMsg(DynamicJsonBuffer &buffer, AsyncWebSocketClient& client, int status, const char* msg) {
-      JsonObject& prop = buffer.createObject();
+  void sendErrorMsg(DynamicJsonDocument &prop, AsyncWebSocketClient& client, int status, const char* msg) {
       prop["error"] = msg;
       prop["status"] = status;
       String jsonStr;
-      prop.printTo(jsonStr);
+      serializeJson(prop, jsonStr);
       client.text(jsonStr.c_str(), jsonStr.length());
   }
 
@@ -198,25 +196,25 @@ class WebThingAdapter {
     // spec. For now each Thing stores its own Websocket connection object therefore.
 
     // Parse request
-    DynamicJsonBuffer newBuffer(1024);
-    JsonObject& newProp = newBuffer.parseObject(rawData);
-    if (!newProp.success()) {
-      sendErrorMsg(newBuffer, *client, 400, "Invalid json");
+    DynamicJsonDocument newProp(1024);
+    auto error = deserializeJson(newProp, rawData);
+    if (error) {
+      sendErrorMsg(newProp, *client, 400, "Invalid json");
       return;
     }
 
     String messageType = newProp["messageType"].as<String>();
-    const JsonVariant& dataVariant = newProp["data"];
+    JsonVariant dataVariant = newProp["data"];
     if (!dataVariant.is<JsonObject>()) {
-      sendErrorMsg(newBuffer, *client, 400, "data must be an object");
+      sendErrorMsg(newProp, *client, 400, "data must be an object");
       return;
     }
 
-    const JsonObject &data = dataVariant.as<const JsonObject&>();
+    JsonObject data = dataVariant.as<JsonObject>();
 
     if (messageType == "setProperty") {
       for (auto kv : data) {
-        ThingProperty* property = device->findProperty(kv.key);
+        ThingProperty* property = device->findProperty(kv.key().c_str());
         if (property) {
           setThingProperty(data, property);
         }
@@ -224,10 +222,10 @@ class WebThingAdapter {
 
       // Send confirmation by sending back the received property object
       String jsonStr;
-      data.printTo(jsonStr);
+      serializeJson(data, jsonStr);
       client->text(jsonStr.c_str(), jsonStr.length());
     } else if (messageType == "requestAction") {
-      sendErrorMsg(newBuffer, *client, 400, "Not supported yet");
+      sendErrorMsg(newProp, *client, 400, "Not supported yet");
     } else if (messageType == "addEventSubscription") {
       // We report back all property state changes. We'd require a map
       // of subscribed properties per websocket connection otherwise
@@ -248,26 +246,26 @@ class WebThingAdapter {
     }
     AsyncResponseStream *response = request->beginResponseStream("application/json");
 
-    DynamicJsonBuffer buf(1024);
-    JsonArray& things = buf.createArray();
+    DynamicJsonDocument buf(1024);
+    JsonArray things = buf.to<JsonArray>();
     ThingDevice* device = this->firstDevice;
     while (device != nullptr) {
-      JsonObject& descr = things.createNestedObject();
+      JsonObject descr = things.createNestedObject();
       this->serializeDevice(descr, device);
       descr["href"] = "/things/" + device->id;
       device = device->next;
     }
 
-    things.printTo(*response);
+    serializeJson(things, *response);
     request->send(response);
 
   }
 
-  void serializePropertyOrEvent(JsonObject& descr, ThingDevice* device, const char* type, bool isProp, ThingItem* item) {
+  void serializePropertyOrEvent(JsonObject descr, ThingDevice* device, const char* type, bool isProp, ThingItem* item) {
     String basePath = "/things/" + device->id + "/"+ type + "/";
-    JsonObject& props = descr.createNestedObject(type);
+    JsonObject props = descr.createNestedObject(type);
     while (item != nullptr) {
-      JsonObject& prop = props.createNestedObject(item->id);
+      JsonObject prop = props.createNestedObject(item->id);
       switch (item->type) {
       case NO_STATE:
         break;
@@ -313,7 +311,7 @@ class WebThingAdapter {
 
         if (hasEnum) {
           enumVal = property->propertyEnum;
-          JsonArray &propEnum = prop.createNestedArray("enum");
+          JsonArray propEnum = prop.createNestedArray("enum");
           while (property->propertyEnum != nullptr && (*enumVal) != nullptr){
             propEnum.add(*enumVal);
             enumVal++;
@@ -326,47 +324,47 @@ class WebThingAdapter {
       }
 
       // 2.9 Property object: A links array (An array of Link objects linking to one or more representations of a Property resource, each with an implied default rel=property.)
-      JsonArray& inline_links = prop.createNestedArray("links");
-      JsonObject& inline_links_prop = inline_links.createNestedObject();
+      JsonArray inline_links = prop.createNestedArray("links");
+      JsonObject inline_links_prop = inline_links.createNestedObject();
       inline_links_prop["href"] = basePath + item->id;
 
       item = item->next;
     }
   }
 
-  void serializeDevice(JsonObject& descr, ThingDevice* device) {
+  void serializeDevice(JsonObject descr, ThingDevice* device) {
     descr["id"] = device->id;
     descr["title"] = device->title;
     descr["@context"] = "https://iot.mozilla.org/schemas";
     // TODO: descr["base"] = ???
 
-    JsonObject& securityDefinitions = descr.createNestedObject("securityDefinitions");
-    JsonObject& nosecSc = securityDefinitions.createNestedObject("nosec_sc");
+    JsonObject securityDefinitions = descr.createNestedObject("securityDefinitions");
+    JsonObject nosecSc = securityDefinitions.createNestedObject("nosec_sc");
     nosecSc["scheme"] = "nosec";
 
-    JsonArray& typeJson = descr.createNestedArray("@type");
+    JsonArray typeJson = descr.createNestedArray("@type");
     const char** type = device->type;
     while ((*type) != nullptr) {
       typeJson.add(*type);
       type++;
     }
 
-    JsonArray& links = descr.createNestedArray("links");
+    JsonArray links = descr.createNestedArray("links");
     {
-      JsonObject& links_prop = links.createNestedObject();
+      JsonObject links_prop = links.createNestedObject();
       links_prop["rel"] = "properties";
       links_prop["href"] = "/things/" + device->id + "/properties";
     }
 
     {
-      JsonObject& links_prop = links.createNestedObject();
+      JsonObject links_prop = links.createNestedObject();
       links_prop["rel"] = "events";
       links_prop["href"] = "/things/" + device->id + "/events";
     }
 
 #ifndef WITHOUT_WS
     {
-      JsonObject& links_prop = links.createNestedObject();
+      JsonObject links_prop = links.createNestedObject();
       links_prop["rel"] = "alternate";
       char buffer [33];
       itoa(port, buffer, 10);
@@ -391,15 +389,15 @@ class WebThingAdapter {
     }
     AsyncResponseStream *response = request->beginResponseStream("application/json");
 
-    DynamicJsonBuffer buf(1024);
-    JsonObject& descr = buf.createObject();
+    DynamicJsonDocument buf(1024);
+    JsonObject descr = buf.to<JsonObject>();
     this->serializeDevice(descr, device);
 
-    descr.printTo(*response);
+    serializeJson(descr, *response);
     request->send(response);
   }
 
-  void serializeThingItem(ThingItem* item, JsonObject& prop) {
+  void serializeThingItem(ThingItem* item, JsonObject prop) {
     switch (item->type) {
     case NO_STATE:
       break;
@@ -421,24 +419,24 @@ class WebThingAdapter {
     }
     AsyncResponseStream *response = request->beginResponseStream("application/json");
 
-    DynamicJsonBuffer buf(256);
-    JsonObject& prop = buf.createObject();
+    DynamicJsonDocument doc(256);
+    JsonObject prop = doc.to<JsonObject>();
     serializeThingItem(item, prop);
-    prop.printTo(*response);
+    serializeJson(prop, *response);
     request->send(response);
   }
 
   void handleThingGetAll(AsyncWebServerRequest *request, ThingDevice* device, ThingItem* rootItem) {
     AsyncResponseStream *response = request->beginResponseStream("application/json");
 
-    DynamicJsonBuffer buf(256);
-    JsonObject& prop = buf.createObject();
+    DynamicJsonDocument doc(256);
+    JsonObject prop = doc.to<JsonObject>();
     ThingItem *item = rootItem;
     while (item != nullptr) {
       serializeThingItem(item, prop);
       item = item->next;
     }
-    prop.printTo(*response);
+    serializeJson(prop, *response);
     request->send(response);
   }
 
@@ -451,7 +449,7 @@ class WebThingAdapter {
     b_has_body_data = true;
   }
 
-  void setThingProperty(const JsonObject& newProp, ThingProperty* property) {
+  void setThingProperty(const JsonObject newProp, ThingProperty* property) {
     const JsonVariant newValue = newProp[property->id];
 
     switch (property->type) {
@@ -485,19 +483,20 @@ class WebThingAdapter {
       return;
     }
 
-    DynamicJsonBuffer newBuffer(256);
-    JsonObject& newProp = newBuffer.parseObject(body_data);
-    if (!newProp.success()) { // unable to parse json
+    DynamicJsonDocument newBuffer(256);
+    auto error = deserializeJson(newBuffer, body_data);
+    if (error) { // unable to parse json
       b_has_body_data = false;
       memset(body_data, 0, sizeof(body_data));
       request->send(500);
       return;
     }
+    JsonObject newProp = newBuffer.to<JsonObject>();
 
     setThingProperty(newProp, property);
 
     AsyncResponseStream *response = request->beginResponseStream("application/json");
-    newProp.printTo(*response);
+    serializeJson(newProp, *response);
     request->send(response);
 
     b_has_body_data = false;
diff --git a/EthernetWebThingAdapter.h b/EthernetWebThingAdapter.h
index 700d570..2d975f0 100644
--- a/EthernetWebThingAdapter.h
+++ b/EthernetWebThingAdapter.h
@@ -332,17 +332,17 @@ class WebThingAdapter {
     sendOk();
     sendHeaders();
 
-    DynamicJsonBuffer buf;
-    JsonArray& things = buf.createArray();
+    DynamicJsonDocument buf(256);
+    JsonArray things = buf.to<JsonArray>();
     ThingDevice* device = firstDevice;
     while (device != nullptr) {
-      JsonObject& descr = things.createNestedObject();
+      JsonObject descr = things.createNestedObject();
       serializeDevice(descr, device);
       descr["href"] = "/things/" + device->id;
       device = device->next;
     }
 
-    things.printTo(client);
+    serializeJson(things, client);
     delay(1);
     client.stop();
   }
@@ -352,11 +352,11 @@ class WebThingAdapter {
     sendOk();
     sendHeaders();
 
-    DynamicJsonBuffer buf;
-    JsonObject& descr = buf.createObject();
+    DynamicJsonDocument buf(256);
+    JsonObject descr = buf.to<JsonObject>();
     serializeDevice(descr, device);
 
-    descr.printTo(client);
+    serializeJson(descr, client);
     delay(1);
     client.stop();
   }
@@ -365,8 +365,7 @@ class WebThingAdapter {
     sendOk();
     sendHeaders();
 
-    DynamicJsonBuffer buf;
-    JsonObject& prop = buf.createObject();
+    DynamicJsonDocument prop(256);
     switch (property->type) {
     case BOOLEAN:
       prop[property->id] = property->getValue().boolean;
@@ -378,7 +377,7 @@ class WebThingAdapter {
       prop[property->id] = *property->getValue().string;
       break;
     }
-    prop.printTo(client);
+    serializeJson(prop, client);
     delay(1);
     client.stop();
   }
@@ -386,8 +385,9 @@ class WebThingAdapter {
   void handlePropertyPut(ThingProperty* property) {
     sendOk();
     sendHeaders();
-    DynamicJsonBuffer newBuffer;
-    JsonObject& newProp = newBuffer.parseObject(content);
+    DynamicJsonDocument newBuffer(256);
+    deserializeJson(newBuffer, content);
+    JsonObject newProp = newBuffer.to<JsonObject>();
     JsonVariant newValue = newProp[property->id];
 
     switch (property->type) {
@@ -431,28 +431,28 @@ class WebThingAdapter {
     retries = 0;
   }
 
-  void serializeDevice(JsonObject& descr, ThingDevice* device) {
+  void serializeDevice(JsonObject descr, ThingDevice* device) {
     descr["id"] = device->id;
     descr["title"] = device->title;
     descr["@context"] = "https://iot.mozilla.org/schemas";
     // TODO: descr["base"] = ???
 
-    JsonObject& securityDefinitions = descr.createNestedObject("securityDefinitions");
-    JsonObject& nosecSc = securityDefinitions.createNestedObject("nosec_sc");
+    JsonObject securityDefinitions = descr.createNestedObject("securityDefinitions");
+    JsonObject nosecSc = securityDefinitions.createNestedObject("nosec_sc");
     nosecSc["scheme"] = "nosec";
 
-    JsonArray& typeJson = descr.createNestedArray("@type");
+    JsonArray typeJson = descr.createNestedArray("@type");
     const char** type = device->type;
     while ((*type) != nullptr) {
       typeJson.add(*type);
       type++;
     }
 
-    JsonObject& props = descr.createNestedObject("properties");
+    JsonObject props = descr.createNestedObject("properties");
 
     ThingProperty* property = device->firstProperty;
     while (property != nullptr) {
-      JsonObject& prop = props.createNestedObject(property->id);
+      JsonObject prop = props.createNestedObject(property->id);
       switch (property->type) {
       case BOOLEAN:
         prop["type"] = "boolean";
@@ -498,7 +498,7 @@ class WebThingAdapter {
 
       if (hasEnum) {
         enumVal = property->propertyEnum;
-        JsonArray &propEnum = prop.createNestedArray("enum");
+        JsonArray propEnum = prop.createNestedArray("enum");
         while (property->propertyEnum != nullptr && (*enumVal) != nullptr){
           propEnum.add(*enumVal);
           enumVal++;
diff --git a/Makefile b/Makefile
index dfd4e51..e909e29 100644
--- a/Makefile
+++ b/Makefile
@@ -44,7 +44,7 @@ USER_LIB_PATH?=${extra_dir}/Arduino/libraries
 
 ArduinoJson_url?=https://github.com/bblanchon/ArduinoJson
 ArduinoJson_dir?=${extra_dir}/Arduino/libraries/ArduinoJson
-ArduinoJson_version?=v5.13.4
+ArduinoJson_version?=v6.13.0
 arduino_lib_dirs+=${ArduinoJson_dir}
 
 ${ArduinoJson_dir}:
diff --git a/README.md b/README.md
index ffd9637..e75dab2 100644
--- a/README.md
+++ b/README.md
@@ -29,9 +29,8 @@ it in your sketchbook's libraries folder.
 
 ### Continuing onwards
 
-Make sure to install the ArduinoJson library if you don't have it installed
-already. Note that you must select ArduinoJson version 5, not the prerelease
-beta version 6.
+Make sure to install the current release of the ArduinoJson library (6) if you
+don't have it installed already.
 
 ![ArduinoJson install process](https://github.com/mozilla-iot/webthing-arduino/raw/master/docs/arduinojson.png)
 
diff --git a/WiFi101WebThingAdapter.h b/WiFi101WebThingAdapter.h
index 040ffc7..4d8fcf0 100644
--- a/WiFi101WebThingAdapter.h
+++ b/WiFi101WebThingAdapter.h
@@ -309,17 +309,17 @@ class WebThingAdapter {
     sendOk();
     sendHeaders();
 
-    DynamicJsonBuffer buf;
-    JsonArray& things = buf.createArray();
+    DynamicJsonDocument buf(256);
+    JsonArray things = buf.to<JsonArray>();
     ThingDevice* device = firstDevice;
     while (device != nullptr) {
-      JsonObject& descr = things.createNestedObject();
+      JsonObject descr = things.createNestedObject();
       serializeDevice(descr, device);
       descr["href"] = "/things/" + device->id;
       device = device->next;
     }
 
-    things.printTo(client);
+    serializeJson(things, client);
     delay(1);
     client.stop();
   }
@@ -329,11 +329,11 @@ class WebThingAdapter {
     sendOk();
     sendHeaders();
 
-    DynamicJsonBuffer buf;
-    JsonObject& descr = buf.createObject();
+    DynamicJsonDocument buf(256);
+    JsonObject descr = buf.to<JsonObject>();
     serializeDevice(descr, device);
 
-    descr.printTo(client);
+    serializeJson(descr, client);
     delay(1);
     client.stop();
   }
@@ -342,8 +342,7 @@ class WebThingAdapter {
     sendOk();
     sendHeaders();
 
-    DynamicJsonBuffer buf;
-    JsonObject& prop = buf.createObject();
+    DynamicJsonDocument prop(256);
     switch (property->type) {
     case NO_STATE:
       break;
@@ -357,7 +356,7 @@ class WebThingAdapter {
       prop[property->id] = *property->getValue().string;
       break;
     }
-    prop.printTo(client);
+    serializeJson(prop, client);
     delay(1);
     client.stop();
   }
@@ -365,8 +364,10 @@ class WebThingAdapter {
   void handlePropertyPut(ThingProperty* property) {
     sendOk();
     sendHeaders();
-    DynamicJsonBuffer newBuffer;
-    JsonObject& newProp = newBuffer.parseObject(content);
+    DynamicJsonDocument newBuffer(256);
+    deserializeJson(newBuffer, content);
+    JsonObject newProp = newBuffer.to<JsonObject>();
+
     JsonVariant newValue = newProp[property->id];
 
     switch (property->type) {
@@ -412,28 +413,28 @@ class WebThingAdapter {
     retries = 0;
   }
 
-  void serializeDevice(JsonObject& descr, ThingDevice* device) {
+  void serializeDevice(JsonObject descr, ThingDevice* device) {
     descr["id"] = device->id;
     descr["title"] = device->title;
     descr["@context"] = "https://iot.mozilla.org/schemas";
     // TODO: descr["base"] = ???
 
-    JsonObject& securityDefinitions = descr.createNestedObject("securityDefinitions");
-    JsonObject& nosecSc = securityDefinitions.createNestedObject("nosec_sc");
+    JsonObject securityDefinitions = descr.createNestedObject("securityDefinitions");
+    JsonObject nosecSc = securityDefinitions.createNestedObject("nosec_sc");
     nosecSc["scheme"] = "nosec";
 
-    JsonArray& typeJson = descr.createNestedArray("@type");
+    JsonArray typeJson = descr.createNestedArray("@type");
     const char** type = device->type;
     while ((*type) != nullptr) {
       typeJson.add(*type);
       type++;
     }
 
-    JsonObject& props = descr.createNestedObject("properties");
+    JsonObject props = descr.createNestedObject("properties");
 
     ThingProperty* property = device->firstProperty;
     while (property != nullptr) {
-      JsonObject& prop = props.createNestedObject(property->id);
+      JsonObject prop = props.createNestedObject(property->id);
       switch (property->type) {
       case NO_STATE:
         break;
@@ -477,7 +478,7 @@ class WebThingAdapter {
 
       if (hasEnum) {
         enumVal = property->propertyEnum;
-        JsonArray &propEnum = prop.createNestedArray("enum");
+        JsonArray propEnum = prop.createNestedArray("enum");
         while (property->propertyEnum != nullptr && (*enumVal) != nullptr){
           propEnum.add(*enumVal);
           enumVal++;
diff --git a/examples/PlatformIO/BME280/platformio.ini b/examples/PlatformIO/BME280/platformio.ini
index fee42b8..8f861ca 100755
--- a/examples/PlatformIO/BME280/platformio.ini
+++ b/examples/PlatformIO/BME280/platformio.ini
@@ -19,7 +19,7 @@ env_default = samw25
 ; https://platformio.org/lib/show/2848/ArduinoMDNS
 lib_deps =
   https://github.com/mozilla-iot/webthing-arduino.git
-  ArduinoJson@5.13.4
+  ArduinoJson@6.13.0
   WiFi101
   ArduinoMDNS
   BME280
diff --git a/examples/PlatformIO/BME280/src/BME280.cpp b/examples/PlatformIO/BME280/src/BME280.cpp
index ac23cb5..72690f8 100755
--- a/examples/PlatformIO/BME280/src/BME280.cpp
+++ b/examples/PlatformIO/BME280/src/BME280.cpp
@@ -59,7 +59,7 @@ BME280I2C::Settings settings(
    BME280::StandbyTime_1000ms,
    BME280::Filter_Off,
    BME280::SpiEnable_False,
-   (BME280I2C::I2CAddr) 0x76 // I2C address. I2C specific.
+   0x76 // I2C address. I2C specific.
 );
 
 BME280I2C bme(settings);
diff --git a/examples/PlatformIO/LED/platformio.ini b/examples/PlatformIO/LED/platformio.ini
index faf88f6..6c0a772 100644
--- a/examples/PlatformIO/LED/platformio.ini
+++ b/examples/PlatformIO/LED/platformio.ini
@@ -18,7 +18,7 @@
 [global]
 lib_deps =
     https://github.com/mozilla-iot/webthing-arduino.git
-    ArduinoJson@5.13.4
+    ArduinoJson@6.13.0
 monitor_speed = 115200
 
 [env:d1]
diff --git a/examples/PlatformIO/TextDisplay/platformio.ini b/examples/PlatformIO/TextDisplay/platformio.ini
index 6aa4f24..de5c682 100644
--- a/examples/PlatformIO/TextDisplay/platformio.ini
+++ b/examples/PlatformIO/TextDisplay/platformio.ini
@@ -17,7 +17,7 @@
 [global]
 lib_deps =
     https://github.com/mozilla-iot/webthing-arduino.git
-    ArduinoJson@5.13.4
+    ArduinoJson@6.13.0
     Adafruit GFX Library
     Adafruit SSD1306
 
diff --git a/library.json b/library.json
index 0cd8d9c..ec4047f 100644
--- a/library.json
+++ b/library.json
@@ -14,7 +14,7 @@
     "license": "Mozilla Public License Version 2.0",
     "platforms": "espressif8266,espressif32,atmelavr",
     "dependencies": {
-        "ArduinoJson": "5.13"
+        "ArduinoJson": "6.13.0"
     },
     "export": {
         "include":
@@ -26,4 +26,4 @@
     "examples": [
         "examples/PlatformIO/*/src/*.cpp"
     ]
-}
\ No newline at end of file
+}