---
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[](https://github.com/bblanchon/ArduinoJson/stargazers)
ArduinoJson is a C++ JSON library for Arduino and IoT (Internet Of Things).
## Features
* [JSON deserialization ](https://arduinojson.org/v6/api/json/deserializejson/?utm_source=github&utm_medium=readme )
* [Optionally decodes UTF-16 escape sequences to UTF-8 ](https://arduinojson.org/v6/api/config/decode_unicode/?utm_source=github&utm_medium=readme )
* [Optionally stores links to the input buffer (zero-copy) ](https://arduinojson.org/v6/api/json/deserializejson/?utm_source=github&utm_medium=readme )
* [Optionally supports comments in the input ](https://arduinojson.org/v6/api/config/enable_comments/?utm_source=github&utm_medium=readme )
* [Optionally filters the input to keep only desired values ](https://arduinojson.org/v6/api/json/deserializejson/?utm_source=github&utm_medium=readme#filtering )
* Supports single quotes as a string delimiter
* Compatible with [NDJSON ](http://ndjson.org/ ) and [JSON Lines ](https://jsonlines.org/ )
* [JSON serialization ](https://arduinojson.org/v6/api/json/serializejson/?utm_source=github&utm_medium=readme )
* [Can write to a buffer or a stream ](https://arduinojson.org/v6/api/json/serializejson/?utm_source=github&utm_medium=readme )
* [Optionally indents the document (prettified JSON) ](https://arduinojson.org/v6/api/json/serializejsonpretty/?utm_source=github&utm_medium=readme )
* [MessagePack serialization ](https://arduinojson.org/v6/api/msgpack/serializemsgpack/?utm_source=github&utm_medium=readme )
* [MessagePack deserialization ](https://arduinojson.org/v6/api/msgpack/deserializemsgpack/?utm_source=github&utm_medium=readme )
* Efficient
* [Twice smaller than the "official" Arduino_JSON library ](https://arduinojson.org/2019/11/19/arduinojson-vs-arduino_json/?utm_source=github&utm_medium=readme )
* [Almost 10% faster than the "official" Arduino_JSON library ](https://arduinojson.org/2019/11/19/arduinojson-vs-arduino_json/?utm_source=github&utm_medium=readme )
* [Consumes roughly 10% less RAM than the "official" Arduino_JSON library ](https://arduinojson.org/2019/11/19/arduinojson-vs-arduino_json/?utm_source=github&utm_medium=readme )
* [Fixed memory allocation, no heap fragmentation ](https://arduinojson.org/v6/api/jsondocument/?utm_source=github&utm_medium=readme )
* [Optionally works without heap memory (zero malloc) ](https://arduinojson.org/v6/api/staticjsondocument/?utm_source=github&utm_medium=readme )
* Deduplicates strings
* Versatile
* Supports [custom allocators (to use external RAM chip, for example) ](https://arduinojson.org/v6/how-to/use-external-ram-on-esp32/?utm_source=github&utm_medium=readme )
* Supports [`String` ](https://arduinojson.org/v6/api/config/enable_arduino_string/?utm_source=github&utm_medium=readme ), [`std::string` ](https://arduinojson.org/v6/api/config/enable_std_string/?utm_source=github&utm_medium=readme ) and [`std::string_view` ](https://arduinojson.org/v6/api/config/enable_string_view/?utm_source=github&utm_medium=readme )
* Supports [`Stream` ](https://arduinojson.org/v6/api/config/enable_arduino_stream/?utm_source=github&utm_medium=readme ) and [`std::istream`/`std::ostream` ](https://arduinojson.org/v6/api/config/enable_std_stream/?utm_source=github&utm_medium=readme )
* Supports [Flash strings ](https://arduinojson.org/v6/api/config/enable_progmem/?utm_source=github&utm_medium=readme )
* Supports [custom readers ](https://arduinojson.org/v6/api/json/deserializejson/?utm_source=github&utm_medium=readme#custom-reader ) and [custom writers ](https://arduinojson.org/v6/api/json/serializejson/?utm_source=github&utm_medium=readme#custom-writer )
* Supports [custom converters ](https://arduinojson.org/news/2021/05/04/version-6-18-0/?utm_source=github&utm_medium=readme )
* Portable
* Usable on any C++ project (not limited to Arduino)
* Compatible with C++98, C++11, C++14 and C++17
* Zero warnings with `-Wall -Wextra -pedantic` and `/W4`
* [Header-only library ](https://en.wikipedia.org/wiki/Header-only )
* Works with virtually any board
* Arduino boards: [Uno ](https://amzn.to/38aL2ik ), [Due ](https://amzn.to/36YkWi2 ), [Micro ](https://amzn.to/35WkdwG ), [Nano ](https://amzn.to/2QTvwRX ), [Mega ](https://amzn.to/36XWhuf ), [Yun ](https://amzn.to/30odURc ), [Leonardo ](https://amzn.to/36XWjlR )...
* Espressif chips: [ESP8266 ](https://amzn.to/36YluV8 ), [ESP32 ](https://amzn.to/2G4pRCB )
* Lolin (WeMos) boards: [D1 mini ](https://amzn.to/2QUpz7q ), [D1 Mini Pro ](https://amzn.to/36UsGSs )...
* Teensy boards: [4.0 ](https://amzn.to/30ljXGq ), [3.2 ](https://amzn.to/2FT0EuC ), [2.0 ](https://amzn.to/2QXUMXj )
* Particle boards: [Argon ](https://amzn.to/2FQHa9X ), [Boron ](https://amzn.to/36WgLUd ), [Electron ](https://amzn.to/30vEc4k ), [Photon ](https://amzn.to/387F9Cd )...
* Texas Instruments boards: [MSP430 ](https://amzn.to/30nJWgg )...
* Tested on all major development environments
* [Arduino IDE ](https://www.arduino.cc/en/Main/Software )
* [Atmel Studio ](http://www.atmel.com/microsite/atmel-studio/ )
* [Atollic TrueSTUDIO ](https://atollic.com/truestudio/ )
* [Energia ](http://energia.nu/ )
* [IAR Embedded Workbench ](https://www.iar.com/iar-embedded-workbench/ )
* [Keil uVision ](http://www.keil.com/ )
* [MPLAB X IDE ](http://www.microchip.com/mplab/mplab-x-ide )
* [Particle ](https://www.particle.io/ )
* [PlatformIO ](http://platformio.org/ )
* [Sloeber plugin for Eclipse ](https://eclipse.baeyens.it/ )
* [Visual Micro ](http://www.visualmicro.com/ )
* [Visual Studio ](https://www.visualstudio.com/ )
* [Even works with online compilers like wandbox.org ](https://wandbox.org/permlink/RlZSKy17DjJ6HcdN )
* [CMake friendly ](https://arduinojson.org/v6/how-to/use-arduinojson-with-cmake/?utm_source=github&utm_medium=readme )
* Well designed
* [Elegant API ](http://arduinojson.org/v6/example/?utm_source=github&utm_medium=readme )
* [Thread-safe ](https://en.wikipedia.org/wiki/Thread_safety )
* Self-contained (no external dependency)
* `const` friendly
* [`for` friendly ](https://arduinojson.org/v6/api/jsonobject/begin_end/?utm_source=github&utm_medium=readme )
* [TMP friendly ](https://en.wikipedia.org/wiki/Template_metaprogramming )
* Handles [integer overflows ](https://arduinojson.org/v6/api/jsonvariant/as/?utm_source=github&utm_medium=readme#integer-overflows )
* Well tested
* [Unit test coverage close to 100% ](https://coveralls.io/github/bblanchon/ArduinoJson?branch=6.x )
* Continuously tested on
* [Visual Studio 2010, 2012, 2013, 2015, 2017, 2019 ](https://ci.appveyor.com/project/bblanchon/arduinojson/branch/6.x )
* [GCC 4.4, 4.6, 4.7, 4.8, 4.9, 5, 6, 7, 8, 9, 10 ](https://github.com/bblanchon/ArduinoJson/actions?query=workflow%3A%22Continuous+Integration%22 )
* [Clang 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 5.0, 6.0, 7, 8, 9, 10 ](https://github.com/bblanchon/ArduinoJson/actions?query=workflow%3A%22Continuous+Integration%22 )
* [Continuously fuzzed with Google OSS Fuzz ](https://bugs.chromium.org/p/oss-fuzz/issues/list?sort=-opened&can=1&q=proj:arduinojson )
* Passes all default checks of [clang-tidy ](https://releases.llvm.org/10.0.0/tools/clang/tools/extra/docs/clang-tidy/ )
* Well documented
* [Tutorials ](https://arduinojson.org/v6/doc/deserialization/?utm_source=github&utm_medium=readme )
* [Examples ](https://arduinojson.org/v6/example/?utm_source=github&utm_medium=readme )
* [How-tos ](https://arduinojson.org/v6/example/?utm_source=github&utm_medium=readme )
* [FAQ ](https://arduinojson.org/v6/faq/?utm_source=github&utm_medium=readme )
* [Troubleshooter ](https://arduinojson.org/v6/troubleshooter/?utm_source=github&utm_medium=readme )
* [Book ](https://arduinojson.org/book/?utm_source=github&utm_medium=readme )
* [Changelog ](CHANGELOG.md )
* Vibrant user community
* Most popular of all Arduino libraries on [GitHub ](https://github.com/search?o=desc&q=arduino+library&s=stars&type=Repositories )
* [Used in hundreds of projects ](https://www.hackster.io/search?i=projects&q=arduinojson )
* [Responsive support ](https://github.com/bblanchon/ArduinoJson/issues?q=is%3Aissue+is%3Aclosed )
## Quickstart
### Deserialization
Here is a program that parses a JSON document with ArduinoJson.
```c++
char json[] = "{\"sensor\":\"gps\",\"time\":1351824120,\"data\":[48.756080,2.302038]}";
DynamicJsonDocument doc(1024);
deserializeJson(doc, json);
const char* sensor = doc["sensor"];
long time = doc["time"];
double latitude = doc["data"][0];
double longitude = doc["data"][1];
```
See the [tutorial on arduinojson.org ](https://arduinojson.org/doc/decoding/?utm_source=github&utm_medium=readme )
### Serialization
Here is a program that generates a JSON document with ArduinoJson:
```c++
DynamicJsonDocument doc(1024);
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 the [tutorial on arduinojson.org ](https://arduinojson.org/doc/encoding/?utm_source=github&utm_medium=readme )
## Support the project ❤️
Do you like this library?
Please [star this project on GitHub ](https://github.com/bblanchon/ArduinoJson/stargazers )!
What? You don't like it but you *love* it?
You can support the project by [purchasing my book ](https://arduinojson.org/book/?utm_source=github&utm_medium=readme ).
Alternatively, you can make a recurring donation via [GitHub Sponsors ](https://github.com/sponsors/bblanchon ).
