ArduinoJson is a C++ JSON library for Arduino and IoT (Internet Of Things).

Features

JSON decoding (comments are supported)
JSON encoding (with optional indentation)
Elegant API, easy to use
Fixed memory allocation (zero malloc)
No data duplication (zero copy)
Portable (written in C++98, can be used in any C++ project)
Self-contained (no external dependency)
Small footprint
Input and output streams
100% code coverage
Header-only library
MIT License
Comprehensive documentation

Compatibility

ArduinoJson works on the following hardware:

Arduino boards: Uno, Due, Mini, Micro, Yun...
Espressif chips: ESP8266, ESP32
WeMos boards: D1, D1 mini, ...
RedBearLab boards: BLE Nano, BLE Mini, WiFi Micro, LOLIN32...
Teensy boards
Intel boards: Edison, Galileo...
Particle boards: Photon, Electron...
Texas Instruments boards: MSP430...

ArduinoJson compiles with zero warning on the following compilers, IDEs, and platforms:

Arduino IDE
PlatformIO
Energia
Visual Micro
Atmel Studio
IAR Embedded Workbench
Atollic TrueSTUDIO
Keil uVision
MPLAB X IDE
GCC
Clang
Visual Studio

Quickstart

Deserialization

Here is a program that parses a JSON document with ArduinoJson.

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

StaticJsonBuffer<200> jsonBuffer;

JsonObject& root = jsonBuffer.parseObject(json);

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

See the tutorial on arduinojson.org

Serialization

Here is a program that generates a JSON document with ArduinoJson:

StaticJsonBuffer<200> jsonBuffer;

JsonObject& root = jsonBuffer.createObject();
root["sensor"] = "gps";
root["time"] = 1351824120;

JsonArray& data = root.createNestedArray("data");
data.add(48.756080);
data.add(2.302038);

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

See the tutorial on arduinojson.org

Documentation

The documentation is available on arduinojson.org, here are some shortcuts:

The Examples show how to use the library in various situations.
The API Reference contains the description of each class and function.
The FAQ has the answer to virtually every question.
The ArduinoJson Assistant writes programs for you!

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