JSON

JavaScript Object Notation (JSON) is a lightweight data-interchange format. It consists of key-value pairs and arrays values, and is used for storing and transmitting data in Minecraft.

In Minecraft, JSON format is used to store the following data:

• Text in the /tellraw and /titleraw commands, books, signs, item names, entity names, world names, scoreboard displays, and text that is displayed through script APIs in Bedrock Edition.
• The pack.mcmeta file that describes a Java Edition resource pack and data pack.
• The manifest.json file that describes a Bedrock Edition add-on.
• Files in a resource pack that define models, colormaps, sound events, texts, fonts, GUI, etc.
• Files in a data pack that define advancements, loot tables, tags, recipes, dimensions, dimension types and predicates.‌^{[Java Edition only]}
• Files in a behavior pack that define entity behaviors, block behaviors, item behaviors, etc.‌^{[Bedrock Edition only]}
• Files in a skin pack that identify the skins being used.‌^{[Bedrock Edition only]}
• Advancements and statistics (as .minecraft/saves/*/data/stats/*.json)
• The profile data for the launcher (as launcher_profiles.json)
• Information about downloaded versions (as version.json)
• Inside the Base64 encoded textures data of player heads and players.‌^{[Java Edition only]}

A JSON file must contain a single JSON value, which can use any of the following five data types: string, number, object, array, and boolean. JSON files can be contained in a single line, however it is often useful to use indentation and line breaks to make a long JSON file more readable.

A string is delimited by quotes and can contain any combination of characters. Some special characters need to be escaped; this is done with a back slash (\).

• "foo"
• "Hello, world"
• "An escaped \" quote within a string"

A number is defined by entering in any number. Numbers can be non-whole, as indicated with a period, and can use exponents with e.

• 2
• -0.5
• 3e6 (=3×10⁶)

An object, also referred to as a compound, is delimited by opening and closing curly brackets and contains key/value pairs. Pairs are separated with commas, keys and associated values are separated with colons. Each contained key needs to have a name that is unique within the object. A value can be of any data type as well (including another object).

{
    "Bob": {
        "ID": 1234,
        "lastName": "Ramsay"
    },
    "Alice": {
        "ID": 2345,
        "lastName": "Berg"
    }
}

Arrays are delimited by opening and closing square brackets and can contain values of any data type, separated by commas. Unlike lists in NBT, values in a JSON array can use different data types.

["Bob", "Alice", "Carlos", "Eve"]

A boolean can be either true or false.

{
    "Steve": {
        "isAlive": true
    },
    "Alex": {
        "isAlive": false
    }
}

• JSON on Wikipedia