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

Features

• JSON deserialization
  
  
  • Optionally decodes UTF-16 escape sequences to UTF-8
  
  
  • Optionally stores links to the input buffer (zero-copy)
  
  
  • Optionally supports comments in the input
  
  
  • Optionally filters the input to keep only desired values
  
  
  • Supports single quotes as a string delimiter
  
  
  • Compatible with NDJSON and JSON Lines
  
  
  
  


• JSON serialization
  
  
  • Can write to a buffer or a stream
  
  
  • Optionally indents the document (prettified JSON)
  
  
  
  


• MessagePack serialization


• MessagePack deserialization


• Efficient
  
  
  • Twice smaller than the "official" Arduino_JSON library
  
  
  • Almost 10% faster than the "official" Arduino_JSON library
  
  
  • Consumes roughly 10% less RAM than the "official" Arduino_JSON library
  
  
  • Fixed memory allocation, no heap fragmentation
  
  
  • Optionally works without heap memory (zero malloc)
  
  
  • Deduplicates strings
  
  
  
  


• Versatile
  
  
  • Supports custom allocators (to use external RAM chip, for example)
  
  
  • Supports String, std::string and std::string_view
  
  
  • Supports Stream and std::istream/std::ostream
  
  
  • Supports Flash strings
  
  
  • Supports custom readers and custom writers
  
  
  • Supports custom converters
  
  
  
  


• 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
  
  
  • Works with virtually any board
    
    
    • Arduino boards: Uno, Due, Micro, Nano, Mega, Yun, Leonardo...
    
    
    • Espressif chips: ESP8266, ESP32
    
    
    • Lolin (WeMos) boards: D1 mini, D1 Mini Pro...
    
    
    • Teensy boards: 4.0, 3.2, 2.0
    
    
    • Particle boards: Argon, Boron, Electron, Photon...
    
    
    • Texas Instruments boards: MSP430...
    
    
    
    
  
  
  • Tested on all major development environments
    
    
    • Arduino IDE
    
    
    • Atmel Studio
    
    
    • Atollic TrueSTUDIO
    
    
    • Energia
    
    
    • IAR Embedded Workbench
    
    
    • Keil uVision
    
    
    • MPLAB X IDE
    
    
    • Particle
    
    
    • PlatformIO
    
    
    • Sloeber plugin for Eclipse
    
    
    • Visual Micro
    
    
    • Visual Studio
    
    
    
    
  
  
  • Even works with online compilers like wandbox.org
  
  
  • CMake friendly
  
  
  
  


• Well designed
  
  
  • Elegant API
  
  
  • Thread-safe
  
  
  • Self-contained (no external dependency)
  
  
  • const friendly
  
  
  • for friendly
  
  
  • TMP friendly
  
  
  • Handles integer overflows
  
  
  
  


• Well tested
  
  
  • Unit test coverage close to 100%
  
  
  • Continuously tested on
    
    
    • Visual Studio 2010, 2012, 2013, 2015, 2017, 2019
    
    
    • GCC 4.4, 4.6, 4.7, 4.8, 4.9, 5, 6, 7, 8, 9, 10, 11
    
    
    • Clang 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 5.0, 6.0, 7, 8, 9, 10
    
    
    
    
  
  
  • Continuously fuzzed with Google OSS Fuzz
  
  
  • Passes all default checks of clang-tidy
  
  
  
  


• Well documented
  
  
  • Tutorials
  
  
  • Examples
  
  
  • How-tos
  
  
  • FAQ
  
  
  • Troubleshooter
  
  
  • Book
  
  
  • Changelog
  
  
  
  


• Vibrant user community
  
  
  • Most popular of all Arduino libraries on GitHub
  
  
  • Used in hundreds of projects
  
  
  • Responsive support
  
  
  
  

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

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

Support the project

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