A JSON object is a collection of key-value pairs, delimited by curly braces {}. It’s the most fundamental structure in JSON, used to represent an entity with named properties, like a person, a product, or a configuration.
Basic syntax
// json
{
"name": "Ana",
"age": 30,
"active": true
}Each pair consists of a key (always a string, in double quotes) and a value, separated by a colon. Different pairs are separated by commas.
Important rules
- Keys always in double quotes, never single or unquoted
- No comma allowed after the last pair (trailing comma)
- Duplicate keys are technically allowed by the syntax, but the behavior is undefined, most parsers just use the last value
Objects can be empty
// json
{}An empty object is perfectly valid JSON.
Objects can contain other objects (nesting)
// json
{
"name": "Ana",
"address": {
"city": "New York",
"zip": "10001"
}
}Object vs array: the key difference
An object uses named keys to access values (data.name), while an array uses numeric position (data[0]). If the order of items doesn’t matter and each one has a “name” that makes sense, it’s usually an object. If order matters and the items are all the same type/category, it’s usually an array.
If you’re unsure about the difference between an object and an array, JSON Validator helps visualize the structure of any JSON clearly.