JSON vs JSONC vs JSON5: What Is the Difference?

JSON is the strict data format defined by RFC 8259. JSONC and JSON5 are relaxed supersets that make files easier for people to write. Every valid JSON document is also valid JSONC and JSON5, but not the other way round.

At a glance

Feature	JSON	JSONC	JSON5
Comments (//, /* */)	No	Yes	Yes
Trailing commas	No	Usually	Yes
Single-quoted strings	No	No	Yes
Unquoted keys	No	No	Yes
Hex numbers, Infinity, NaN	No	No	Yes
Multi-line strings	No	No	Yes
Native parser in every language	Yes	No	No

JSON: for data exchange

Use strict JSON for API requests and responses, data files, and anything another program will read. Every language has a fast, built-in parser, and there is only one way to interpret a document.

JSONC: JSON with comments

JSONC adds comments and, in most tools, trailing commas. It is used for configuration files people edit by hand, such as VS Code’s settings.json and TypeScript’s tsconfig.json.

{
  // Use two-space indentation
  "editor.tabSize": 2,
}

JSON5: JSON for humans

JSON5 goes further and borrows more of JavaScript’s syntax: single quotes, unquoted keys, hexadecimal numbers and multi-line strings. It needs a dedicated parser library.

{
  name: 'getjsonviewer',
  maxSize: 0x10000,
}

Converting JSONC or JSON5 to strict JSON

If a tool rejects your file with a syntax error, it probably expects strict JSON. Paste the file into the JSON repair tool and press Fix. Comments are removed, quotes are normalised and trailing commas dropped, leaving valid JSON you can format or validate.