---
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[](https://ci.appveyor.com/project/bblanchon/arduinojson/branch/6.x)
[](https://bugs.chromium.org/p/oss-fuzz/issues/list?sort=-opened&can=1&q=proj:arduinojson)
[](https://coveralls.io/github/bblanchon/ArduinoJson?branch=6.x)
[](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).