diff --git a/td/generate/scheme/td_api.tl b/td/generate/scheme/td_api.tl
index b584039fc..b7ee0b847 100644
--- a/td/generate/scheme/td_api.tl
+++ b/td/generate/scheme/td_api.tl
@@ -3445,6 +3445,13 @@ getInviteText = Text;
 getDeepLinkInfo link:string = DeepLinkInfo;
 
 
+//@description Returns application config, provided by the server. Can be called before authorization
+getApplicationConfig = JsonValue;
+
+//@description Saves application log event on the server. Can be called before authorization @type Event type @chat_id Optional chat identifier, associated with the event @data The log event data
+saveApplicationLogEvent type:string chat_id:int53 data:JsonValue = Ok;
+
+
 //@description Adds a proxy server for network requests. Can be called before authorization @server Proxy server IP address @port Proxy server port @enable True, if the proxy should be enabled @type Proxy type
 addProxy server:string port:int32 enable:Bool type:ProxyType = Proxy;
 
diff --git a/td/generate/scheme/td_api.tlo b/td/generate/scheme/td_api.tlo
index 33eaa4fe9..fe81076e7 100644
Binary files a/td/generate/scheme/td_api.tlo and b/td/generate/scheme/td_api.tlo differ
diff --git a/td/telegram/JsonValue.cpp b/td/telegram/JsonValue.cpp
index 226ffc829..ad26b4830 100644
--- a/td/telegram/JsonValue.cpp
+++ b/td/telegram/JsonValue.cpp
@@ -6,8 +6,11 @@
 //
 #include "td/telegram/JsonValue.h"
 
+#include "td/telegram/misc.h"
+
 #include "td/utils/JsonBuilder.h"
 #include "td/utils/misc.h"
+#include "td/utils/utf8.h"
 
 namespace td {
 
@@ -45,6 +48,82 @@ Result<td_api::object_ptr<td_api::JsonValue>> get_json_value(MutableSlice json)
   return get_json_value_object(json_value);
 }
 
+static td_api::object_ptr<td_api::jsonObjectMember> convert_json_value_member_object(
+    const telegram_api::object_ptr<telegram_api::jsonObjectValue> &json_object_value) {
+  CHECK(json_object_value != nullptr);
+  return td_api::make_object<td_api::jsonObjectMember>(json_object_value->key_,
+                                                       convert_json_value_object(json_object_value->value_));
+}
+
+td_api::object_ptr<td_api::JsonValue> convert_json_value_object(
+    const tl_object_ptr<telegram_api::JSONValue> &json_value) {
+  CHECK(json_value != nullptr);
+  switch (json_value->get_id()) {
+    case telegram_api::jsonNull::ID:
+      return td_api::make_object<td_api::jsonValueNull>();
+    case telegram_api::jsonBool::ID:
+      return td_api::make_object<td_api::jsonValueBoolean>(
+          static_cast<const telegram_api::jsonBool *>(json_value.get())->value_);
+    case telegram_api::jsonNumber::ID:
+      return td_api::make_object<td_api::jsonValueNumber>(
+          static_cast<const telegram_api::jsonNumber *>(json_value.get())->value_);
+    case telegram_api::jsonString::ID:
+      return td_api::make_object<td_api::jsonValueString>(
+          static_cast<const telegram_api::jsonString *>(json_value.get())->value_);
+    case telegram_api::jsonArray::ID:
+      return td_api::make_object<td_api::jsonValueArray>(
+          transform(static_cast<const telegram_api::jsonArray *>(json_value.get())->value_, convert_json_value_object));
+    case telegram_api::jsonObject::ID:
+      return td_api::make_object<td_api::jsonValueObject>(transform(
+          static_cast<const telegram_api::jsonObject *>(json_value.get())->value_, convert_json_value_member_object));
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+
+static telegram_api::object_ptr<telegram_api::jsonObjectValue> convert_json_value_member(
+    td_api::object_ptr<td_api::jsonObjectMember> &&json_object_member) {
+  CHECK(json_object_member != nullptr);
+  if (!clean_input_string(json_object_member->key_)) {
+    json_object_member->key_.clear();
+  }
+  return telegram_api::make_object<telegram_api::jsonObjectValue>(
+      json_object_member->key_, convert_json_value(std::move(json_object_member->value_)));
+}
+
+tl_object_ptr<telegram_api::JSONValue> convert_json_value(td_api::object_ptr<td_api::JsonValue> &&json_value) {
+  if (json_value == nullptr) {
+    return td_api::make_object<telegram_api::jsonNull>();
+  }
+  switch (json_value->get_id()) {
+    case td_api::jsonValueNull::ID:
+      return telegram_api::make_object<telegram_api::jsonNull>();
+    case td_api::jsonValueBoolean::ID:
+      return telegram_api::make_object<telegram_api::jsonBool>(
+          static_cast<const td_api::jsonValueBoolean *>(json_value.get())->value_);
+    case td_api::jsonValueNumber::ID:
+      return telegram_api::make_object<telegram_api::jsonNumber>(
+          static_cast<const td_api::jsonValueNumber *>(json_value.get())->value_);
+    case td_api::jsonValueString::ID: {
+      auto &str = static_cast<td_api::jsonValueString *>(json_value.get())->value_;
+      if (!clean_input_string(str)) {
+        str.clear();
+      }
+      return telegram_api::make_object<telegram_api::jsonString>(str);
+    }
+    case td_api::jsonValueArray::ID:
+      return telegram_api::make_object<telegram_api::jsonArray>(
+          transform(std::move(static_cast<td_api::jsonValueArray *>(json_value.get())->values_), convert_json_value));
+    case td_api::jsonValueObject::ID:
+      return telegram_api::make_object<telegram_api::jsonObject>(transform(
+          std::move(static_cast<td_api::jsonValueObject *>(json_value.get())->members_), convert_json_value_member));
+    default:
+      UNREACHABLE();
+      return nullptr;
+  }
+}
+
 namespace {
 
 class JsonableJsonValue : public Jsonable {
@@ -66,9 +145,16 @@ class JsonableJsonValue : public Jsonable {
       case td_api::jsonValueNumber::ID:
         *scope << static_cast<const td_api::jsonValueNumber *>(json_value_)->value_;
         break;
-      case td_api::jsonValueString::ID:
-        *scope << static_cast<const td_api::jsonValueString *>(json_value_)->value_;
+      case td_api::jsonValueString::ID: {
+        auto &str = static_cast<const td_api::jsonValueString *>(json_value_)->value_;
+        if (!check_utf8(str)) {
+          LOG(ERROR) << "Have incorrect UTF-8 string " << str;
+          *scope << "";
+        } else {
+          *scope << str;
+        }
         break;
+      }
       case td_api::jsonValueArray::ID: {
         auto array = scope->enter_array();
         for (auto &value : static_cast<const td_api::jsonValueArray *>(json_value_)->values_) {
@@ -80,7 +166,11 @@ class JsonableJsonValue : public Jsonable {
         auto object = scope->enter_object();
         for (auto &member : static_cast<const td_api::jsonValueObject *>(json_value_)->members_) {
           if (member != nullptr) {
-            object << ctie(member->key_, JsonableJsonValue(member->value_.get()));
+            if (!check_utf8(member->key_)) {
+              LOG(ERROR) << "Have incorrect UTF-8 object key " << member->key_;
+            } else {
+              object << ctie(member->key_, JsonableJsonValue(member->value_.get()));
+            }
           }
         }
         break;
diff --git a/td/telegram/JsonValue.h b/td/telegram/JsonValue.h
index 36099efc8..575bfb211 100644
--- a/td/telegram/JsonValue.h
+++ b/td/telegram/JsonValue.h
@@ -7,6 +7,7 @@
 #pragma once
 
 #include "td/telegram/td_api.h"
+#include "td/telegram/telegram_api.h"
 
 #include "td/utils/common.h"
 #include "td/utils/Slice.h"
@@ -16,6 +17,11 @@ namespace td {
 
 Result<td_api::object_ptr<td_api::JsonValue>> get_json_value(MutableSlice json);
 
+td_api::object_ptr<td_api::JsonValue> convert_json_value_object(
+    const tl_object_ptr<telegram_api::JSONValue> &json_value);
+
+tl_object_ptr<telegram_api::JSONValue> convert_json_value(td_api::object_ptr<td_api::JsonValue> &&json_value);
+
 string get_json_string(const td_api::JsonValue *json_value);
 
 }  // namespace td
diff --git a/td/telegram/Td.cpp b/td/telegram/Td.cpp
index b389c2459..8aef48854 100644
--- a/td/telegram/Td.cpp
+++ b/td/telegram/Td.cpp
@@ -497,6 +497,64 @@ class GetDeepLinkInfoQuery : public Td::ResultHandler {
   }
 };
 
+class GetAppConfigQuery : public Td::ResultHandler {
+  Promise<tl_object_ptr<td_api::JsonValue>> promise_;
+
+ public:
+  explicit GetAppConfigQuery(Promise<tl_object_ptr<td_api::JsonValue>> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send() {
+    send_query(G()->net_query_creator().create(create_storer(telegram_api::help_getAppConfig())));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::help_getAppConfig>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    auto result = result_ptr.move_as_ok();
+    promise_.set_value(convert_json_value_object(result));
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
+class SaveAppLogQuery : public Td::ResultHandler {
+  Promise<Unit> promise_;
+
+ public:
+  explicit SaveAppLogQuery(Promise<Unit> &&promise) : promise_(std::move(promise)) {
+  }
+
+  void send(const string &type, int64 peer_id, tl_object_ptr<telegram_api::JSONValue> &&data) {
+    CHECK(data != nullptr);
+    vector<telegram_api::object_ptr<telegram_api::inputAppEvent>> input_app_events;
+    input_app_events.push_back(
+        make_tl_object<telegram_api::inputAppEvent>(G()->server_time_cached(), type, peer_id, std::move(data)));
+    send_query(
+        G()->net_query_creator().create(create_storer(telegram_api::help_saveAppLog(std::move(input_app_events)))));
+  }
+
+  void on_result(uint64 id, BufferSlice packet) override {
+    auto result_ptr = fetch_result<telegram_api::help_saveAppLog>(packet);
+    if (result_ptr.is_error()) {
+      return on_error(id, result_ptr.move_as_error());
+    }
+
+    bool result = result_ptr.move_as_ok();
+    LOG_IF(ERROR, !result) << "Receive false from help.saveAppLog";
+    promise_.set_value(Unit());
+  }
+
+  void on_error(uint64 id, Status status) override {
+    promise_.set_error(std::move(status));
+  }
+};
+
 /*** Td ***/
 /** Td queries **/
 class TestQuery : public Td::ResultHandler {
@@ -3174,6 +3232,8 @@ bool Td::is_preauthentication_request(int32 id) {
     case td_api::getStorageStatisticsFast::ID:
     case td_api::getCountryCode::ID:
     case td_api::getDeepLinkInfo::ID:
+    case td_api::getApplicationConfig::ID:
+    case td_api::saveApplicationLogEvent::ID:
     case td_api::addProxy::ID:
     case td_api::editProxy::ID:
     case td_api::enableProxy::ID:
@@ -6710,6 +6770,18 @@ void Td::on_request(uint64 id, td_api::getDeepLinkInfo &request) {
   create_handler<GetDeepLinkInfoQuery>(std::move(promise))->send(request.link_);
 }
 
+void Td::on_request(uint64 id, const td_api::getApplicationConfig &request) {
+  CREATE_REQUEST_PROMISE();
+  create_handler<GetAppConfigQuery>(std::move(promise))->send();
+}
+
+void Td::on_request(uint64 id, td_api::saveApplicationLogEvent &request) {
+  CLEAN_INPUT_STRING(request.type_);
+  auto result = convert_json_value(std::move(request.data_));
+  CREATE_OK_REQUEST_PROMISE();
+  create_handler<SaveAppLogQuery>(std::move(promise))->send(request.type_, request.chat_id_, std::move(result));
+}
+
 void Td::on_request(uint64 id, td_api::addProxy &request) {
   CLEAN_INPUT_STRING(request.server_);
   CREATE_REQUEST_PROMISE();
diff --git a/td/telegram/Td.h b/td/telegram/Td.h
index 4d0aa0eee..d909cabe8 100644
--- a/td/telegram/Td.h
+++ b/td/telegram/Td.h
@@ -892,6 +892,10 @@ class Td final : public NetQueryCallback {
 
   void on_request(uint64 id, td_api::getDeepLinkInfo &request);
 
+  void on_request(uint64 id, const td_api::getApplicationConfig &request);
+
+  void on_request(uint64 id, td_api::saveApplicationLogEvent &request);
+
   void on_request(uint64 id, td_api::addProxy &request);
 
   void on_request(uint64 id, td_api::editProxy &request);
diff --git a/td/telegram/cli.cpp b/td/telegram/cli.cpp
index fadbee26f..cbc7e5af3 100644
--- a/td/telegram/cli.cpp
+++ b/td/telegram/cli.cpp
@@ -2389,15 +2389,21 @@ class CliClient final : public Actor {
       execute(make_tl_object<td_api::cleanFileName>(args));
     } else if (op == "gjv") {
       execute(td_api::make_object<td_api::getJsonValue>(args));
+    } else if (op == "gjvtest") {
+      execute(td_api::make_object<td_api::getJsonValue>("\"aba\200caba\""));
+      execute(td_api::make_object<td_api::getJsonValue>("\"\\u0080\""));
+      execute(td_api::make_object<td_api::getJsonValue>("\"\\uD800\""));
     } else if (op == "gjs") {
-      execute(td_api::make_object<td_api::getJsonString>());
-      execute(td_api::make_object<td_api::getJsonString>(td_api::make_object<td_api::jsonValueNull>()));
-      execute(td_api::make_object<td_api::getJsonString>(td_api::make_object<td_api::jsonValueBoolean>(true)));
-      execute(td_api::make_object<td_api::getJsonString>(td_api::make_object<td_api::jsonValueNumber>(123456789123.0)));
-      execute(
-          td_api::make_object<td_api::getJsonString>(td_api::make_object<td_api::jsonValueString>(string("aba\x00"
-                                                                                                         "caba",
-                                                                                                         8))));
+      auto test_get_json_string = [&](auto &&json_value) {
+        execute(td_api::make_object<td_api::getJsonString>(std::move(json_value)));
+      };
+
+      test_get_json_string(nullptr);
+      test_get_json_string(td_api::make_object<td_api::jsonValueNull>());
+      test_get_json_string(td_api::make_object<td_api::jsonValueBoolean>(true));
+      test_get_json_string(td_api::make_object<td_api::jsonValueNumber>(123456789123.0));
+      test_get_json_string(td_api::make_object<td_api::jsonValueString>(string("aba\0caba", 8)));
+      test_get_json_string(td_api::make_object<td_api::jsonValueString>("aba\200caba"));
 
       auto inner_array = td_api::make_object<td_api::jsonValueArray>();
       inner_array->values_.push_back(td_api::make_object<td_api::jsonValueBoolean>(false));
@@ -2406,16 +2412,33 @@ class CliClient final : public Actor {
       array->values_.push_back(std::move(inner_array));
       array->values_.push_back(td_api::make_object<td_api::jsonValueNull>());
       array->values_.push_back(td_api::make_object<td_api::jsonValueNumber>(-1));
-      execute(td_api::make_object<td_api::getJsonString>(std::move(array)));
+      test_get_json_string(std::move(array));
 
       auto object = td_api::make_object<td_api::jsonValueObject>();
       object->members_.push_back(
           td_api::make_object<td_api::jsonObjectMember>("", td_api::make_object<td_api::jsonValueString>("test")));
       object->members_.push_back(td_api::make_object<td_api::jsonObjectMember>("a", nullptr));
+      object->members_.push_back(td_api::make_object<td_api::jsonObjectMember>("\x80", nullptr));
       object->members_.push_back(nullptr);
       object->members_.push_back(
           td_api::make_object<td_api::jsonObjectMember>("a", td_api::make_object<td_api::jsonValueNull>()));
-      execute(td_api::make_object<td_api::getJsonString>(std::move(object)));
+      test_get_json_string(std::move(object));
+    } else if (op == "gac") {
+      send_request(td_api::make_object<td_api::getApplicationConfig>());
+    } else if (op == "sale") {
+      string type;
+      string chat_id;
+      string json;
+      std::tie(type, args) = split(args);
+      std::tie(chat_id, json) = split(args);
+
+      auto result = execute(td_api::make_object<td_api::getJsonValue>(json));
+      if (result->get_id() == td_api::error::ID) {
+        LOG(ERROR) << to_string(result);
+      } else {
+        send_request(td_api::make_object<td_api::saveApplicationLogEvent>(
+            type, as_chat_id(chat_id), move_tl_object_as<td_api::JsonValue>(result)));
+      }
     } else {
       op_not_found_count++;
     }