Trailing Commas (the #1 mistake) [#1-trailing-commas-the-1-mistake]
JSON does **not** allow a comma after the last item in an object or array.
```json
// WRONG
{
"name": "Steve",
"age": 25,
}
// CORRECT
{
"name": "Steve",
"age": 25
}
```
The same applies to arrays:
```json
// WRONG
["a", "b", "c",]
// CORRECT
["a", "b", "c"]
```
Missing Quotes Around Keys [#2-missing-quotes-around-keys]
In JSON, **all keys must be quoted** with double quotes.
```json
// WRONG
{ name: "Steve" }
// CORRECT
{ "name": "Steve" }
```
This is different from JavaScript, where unquoted keys are allowed. JSON is strict.
Single Quotes Instead of Double [#3-single-quotes-instead-of-double]
JSON requires **double quotes** for both keys and string values. Single quotes are not allowed anywhere.
```json
// WRONG
{ 'name': 'Steve' }
// CORRECT
{ "name": "Steve" }
```
Mismatched Brackets [#4-mismatched-brackets]
Every `{` must have a `}`. Every `[` must have a `]`. Editors with bracket matching catch this immediately.
```json
// WRONG (missing closing })
{
"settings": {
"enabled": true
}
// CORRECT
{
"settings": {
"enabled": true
}
}
```
Comments [#5-comments]
JSON does **not** support comments. No `//`, no `/* */`, no `#`.
```json
// WRONG (// is not valid JSON)
{
"name": "Steve" // the player
}
// CORRECT (no comments)
{
"name": "Steve"
}
```
> **Workaround:** Some Minecraft files (like `pack.mcmeta`) tolerate `_comment` fields as a convention: `"_comment": "this is ignored by Minecraft"`.
Fix It [#fix-it]