If you have worked with websites, APIs or apps, you have probably seen JSON. This beginner-friendly guide explains what JSON is, why it matters, and how to work with it.
What is JSON?
JSON (JavaScript Object Notation) is a lightweight text format for storing and exchanging data. It uses simple key-value pairs and is easy for both humans and machines to read, which is why it has become the standard for web APIs.
What JSON looks like
JSON organises data into objects (in curly braces) and arrays (in square brackets). Each piece of data has a name and a value, for example a person’s name, age and city. When JSON gets messy, our JSON Formatter beautifies it into readable, indented form and checks that it is valid.
Working with JSON
You will often need to convert between formats. If your data is in a spreadsheet, the CSV to JSON Converter turns rows into JSON objects instantly. For debugging tokens, the JWT Decoder shows the JSON inside a JSON Web Token.
Common JSON mistakes
The most frequent errors are missing commas, trailing commas, and unquoted keys. Running your JSON through a validator catches these in seconds so you can fix them before they break your code.
Frequently asked questions
Is JSON a programming language? No — it is a data format. It originated from JavaScript but is now used by almost every language.
What is the difference between JSON and CSV? CSV is a flat table of rows and columns; JSON can represent nested, structured data.