Fix Single Quotes in JSON

Why Single Quotes Fail

Strict RFC 8259 JSON only accepts double-quoted strings. A parser will reject {'name':'Ada'} even though JavaScript developers may recognize the shape.

Broken Example

{
  'name': 'Ada',
  'active': true
}

Fixed JSON

{
  "name": "Ada",
  "active": true
}

Same data, single quotes swapped for double quotes around both keys and string values.

How Different Languages Report It

The error message varies by parser, but the root cause and the fix are identical:

Language / parser	Error message
JavaScript (JSON.parse, V8)	SyntaxError: Expected property name or '}' in JSON at position 1 (Node 22+) / Unexpected token ' (older runtimes)
Python (json.loads)	json.decoder.JSONDecodeError: Expecting property name enclosed in double quotes: line 1 column 2 (char 1)
Go (encoding/json)	invalid character '\'' looking for beginning of object key string
jq	parse error: Expected string at line 1, column 2

Single-quoted JSON is part of the broader Unexpected token family — the ' row in that table routes back here.

Where Single-Quoted Text Comes From

Python's repr() and dict printing, JavaScript object literals copied from console output, Ruby hash inspection, and many LLM responses all use single quotes. None of these are JSON — they are language-native literals that happen to look similar. The fix is always the same direction (single → double); the question is just how to do it safely.

Why Find-and-Replace Is Risky

A blind replace of ' with " breaks any value that contains an apostrophe:

// ❌ Naive replace — turns one error into a different one
"{ 'note': 'it\\'s fine' }".replace(/'/g, '"')
// → { "note": "it\"s fine" }   ← the " inside the value now ends the string

After replacement, the escaped single quote inside the value becomes an unescaped double quote, which collides with the new string delimiter. A safe converter has to track string-context boundaries and only swap the delimiters, not interior characters.

The Safe Conversion Strategy

Tokenize the input first: walk the text, identify string boundaries by their opening quote, and rebuild each token with double quotes — escaping any interior double quotes and unescaping the now-redundant escaped single quotes. Paste the payload into JSON Fix to do this in one pass, in your browser; then run the result through the strict JSON validator to confirm nothing else is wrong.

Related JSON Syntax Errors

Single-quoted JSON often arrives with other JavaScript-style sins in the same payload: unquoted keys, trailing commas, line comments, or undefined values. After fixing quotes, validate the result to surface anything still left. The repair workflow hub walks through the full sequence.

FAQ

Are single-quoted strings valid in JSON5?

Yes — JSON5 allows them. JSON5 is a human-edit-friendly superset (used by some build tools and config formats) but is not RFC 8259 JSON; don't use it for wire protocols, API payloads, or anything crossing a language boundary.

Will Python's json.loads accept single quotes?

No. If the source really is a Python literal (the output of print(some_dict), for example), use ast.literal_eval instead of json.loads — it parses Python syntax, including single quotes and tuples. If the source is meant to be JSON, convert the quotes first using the safe-conversion strategy above.

Do JSON keys need double quotes too?

Yes — keys are strings, same rule. { "name": "Ada" } is valid; { name: "Ada" } and { 'name': "Ada" } are both rejected.

For the deeper explainer on why JSON requires double quotes — and how this differs from a JavaScript object literal — see JSON vs JavaScript object: why single quotes aren't allowed.

See also

This guide is one stop in a larger repair workflow that covers trailing commas, unquoted keys, single quotes, and stringified-object errors. Open the hub for the full sequence.

Sources

• RFC 8259 — the JSON Data Interchange Format (IETF, the canonical JSON grammar)
• ECMA-404 — the JSON Data Interchange Syntax
• MDN — JSON.parse (the strict parser that emits this error in JavaScript)
• JSON5 — the human-edit-friendly superset that does allow single quotes

Last reviewed June 2026.