📟 C++ JSON library for IoT. Simple and efficient.
Latest commit ef12c74 Dec 4, 2018



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


  • 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


ArduinoJson works on the following hardware:

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



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


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");

// This prints:
// {"sensor":"gps","time":1351824120,"data":[48.756080,2.302038]}

See the tutorial on arduinojson.org


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!

Do you like this library? Please star this project on GitHub!

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