ArduinoJson

The best JSON library for 
  • Arduino UNO
  • Arduino Leonardo
  • Arduino Mini
  • Arduino Micro
  • Arduino Mega
  • Arduino Zero
  • Arduino Due
  • Arduino Yún
  • Arduino M0
  • Arduino MKRZero
  • Arduino MKR1000
  • ESP8266
  • ESP32
  • Teensy
  • Intel Galileo
  • Intel Edison
  • MSP430
  • RedBearLab BLE Nano
  • RedBearLab BLE Mini
  • WeMos D1
  • Atmel Studio
  • Energia
  • IAR Embedded Workbench
  • PlatformIO
  • Visual Micro
  • MCUXpresso
  • Nios II

Quickstart

Serialization

JsonDocument doc;

doc["sensor"] = "gps";
doc["time"] = 1351824120;
doc["data"][0] = 48.756080;
doc["data"][1] = 2.302038;

serializeJson(doc, Serial);
// This prints:
// {"sensor":"gps","time":1351824120,"data":[48.756080,2.302038]}

See Serialization example and Serialization tutorial.

Deserialization

char json[] = "{\"sensor\":\"gps\",\"time\":1351824120,\"data\":[48.756080,2.302038]}";

JsonDocument doc;
deserializeJson(doc, json);

const char* sensor = doc["sensor"];
long time          = doc["time"];
double latitude    = doc["data"][0];
double longitude   = doc["data"][1];

See Deserialization example and Deserialization tutorial.

Features

Intuitive Syntax

ArduinoJson has a simple and intuitive syntax to handle objects and arrays.

Fetch data:

const char* city = doc["city"];
double temp = doc["weather"]["temp"];

Set data:

doc["city"] = "Paris";
doc["weather"]["temp"] = 21.2;

Serialize and Deserialize

ArduinoJson supports both JSON serialization and deserialization.

Read JSON:

deserializeJson(doc, myInput);

…modify:

doc["last_modification"] = time();

…write back:

serializeJson(doc, myOutput);

Input filter

ArduinoJson can filter large inputs to keep only the fields that are relevant to your application, thereby saving a lot of memory.

JsonDocument filter;
filter["list"][0]["temperature"] = true;

deserializeJson(doc, input, DeserializationOption::Filter(filter));

Parse From Stream

ArduinoJson can parse directly from an input Stream or std::istream

Parse input from the serial port:

deserializeJson(doc, Serial);

…an Ethernet connection

deserializeJson(doc, ethernetClient);

…or a Wifi connection

deserializeJson(doc, wifiClient);

It also supports custom reader types.

Print to Stream

ArduinoJson is able to print directly to a Print or std::ostream

Send the JSON to the serial port:

serializeJson(doc, Serial);

…an Ethernet connection

serializeJson(doc, ethernetClient);

…or a Wifi connection

serializeJson(doc, wifiClient);

It also supports custom writer types.

Indented output

ArduinoJson can produce compact:

{"ports":[80,