This is the Assistant for ArduinoJson 6.16.1. Make sure the same version is installed on your computer.


Examples: OpenWeatherMap, Weather Underground

Input length: <% inputLength %>

Memory pool size



<% expression %>

Additional bytes for strings duplication

<% extraBytes %>

Platform Size
<% arch %>
<% result.size[0] %>+<% result.size[1] %> = <% result.size[0] + result.size[1] %>

Sizes can be significantly larger on a computer.

⚠️ The programs below assume you defined ARDUINOJSON_USE_LONG_LONG to 1

Parsing program

Serializing program

<% serializerCode %>

See also: Serialization Tutorial

Support the project and learn at the same time

Mastering ArduinoJson

Do you want to learn more about ArduinoJson?

Check out the book Mastering ArduinoJson, the official manual for ArduinoJson.

With this book, you will:

  • Refresh your knowledge of essential C++ concepts
  • Learn how to deserialize JSON
  • Learn how to serialize JSON
  • Open the hood an see how the library works
  • Learn how to troubleshoot your programs
  • Study new examples

If you never used ArduinoJson, you will appreciate this book because it guides you through your learning. It starts with the basic usage of the library and increments the complexity step by step. The last chapter analyzes several example projects and explains the design choices. It is a much better way to learn than blindly copy-pasting the examples.

If you are already using ArduinoJson, you will learn how to get the best performance and the most straightforward code. You will discover that many examples found on the Internet are suboptimal and even dangerous. The sample projects will give you a sense of how the library should be used and will give you a new perspective on your projects.

Purchasing the book is also a great way to thank the author of the library.

Become a supporter of the project! Learn how to use ArduinoJson