Remove Trailing Commas from JSON

What Is a Trailing Comma in JSON?

A trailing comma is a comma after the last element in a JSON object or array, immediately before the closing } or ]. While JavaScript ES5+ and most modern parsers allow trailing commas, the JSON specification (RFC 8259) does not.

{
  "name": "Alice",
  "age": 30,
}

{
  "name": "Alice",
  "age": 30
}

Why Trailing Commas Break JSON Parsers

Per RFC 8259, the grammar for a JSON object is:

object = begin-object [ member *( value-separator member ) ] end-object

There is no provision for a comma after the last member. Parsers that implement this spec strictly — including Python's json.loads(), JavaScript's JSON.parse(), and most API validators — will throw a SyntaxError.

Trailing Commas in Arrays Too

[
  "apple",
  "banana",
  "cherry",
]

[
  "apple",
  "banana",
  "cherry"
]

Why JSONFix.ai vs. a Simple Find-Replace?

A regex like ,\s*([}\]]) works for simple cases but breaks on JSON that contains commas inside string values. JSONFix.ai uses a proper AST-based repair engine that understands JSON structure — it only removes trailing commas in the right places.

Plus, your JSON might have more than one issue. JSONFix.ai fixes everything in one pass and explains every change.