How to Fix JSON Single Quotes: The Complete Guide

Single-quoted JSON breaks every parser — Python's json.loads, JavaScript's JSON.parse, and every API client on the planet. The fix is straightforward once you understand the rule.

This article was originally published at AI JSONMedic.

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Why JSON Rejects Single Quotes

JSON is defined by RFC 8259, which requires all strings — both keys and values — to be wrapped in double quotes only. Single quotes are simply not part of the JSON specification.

This means the following is invalid JSON:

// INVALID
{'name': 'Alice', 'age': 30}

The valid form:

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

There is no parser setting or "loose mode" that accepts single-quoted JSON.

What Causes the Single Quote Error

Python dictionary literals. When you call str() on a Python dict, Python prints it with single quotes. This is NOT valid JSON:

data = {"name": "Alice"}
print(str(data))
# Output: {'name': 'Alice'}  ← NOT valid JSON

LLM and AI output. Language models sometimes generate Python-dict-style output instead of strict JSON.

Manual editing. Developers who write JSON by hand sometimes use single quotes from JavaScript or Python habit.

Fix in Python

Option 1 — Use json.dumps() instead of str()

import json

data = {"name": "Alice", "age": 30}
good = json.dumps(data)
print(good)
# Output: {"name": "Alice", "age": 30}

Option 2 — ast.literal_eval for Python dict strings

If the string is specifically Python dict syntax, ast.literal_eval is the most reliable repair:

import ast, json

broken = "{'name': \"it's Alice\", 'city': 'London'}"
data = ast.literal_eval(broken)
valid_json = json.dumps(data)

Option 3 — json-repair library for production

from json_repair import repair_json

broken = "{'name': 'Alice', 'scores': [95, 87, 91]}"
fixed = repair_json(broken)
# Output: {"name": "Alice", "scores": [95, 87, 91]}

Fix in JavaScript

// Never build JSON with single quotes — use JSON.stringify()
const data = { name: "Alice", age: 30 };
const validJson = JSON.stringify(data);

// For basic strings without apostrophes in values:
const broken = "{'name': 'Alice', 'age': 30}";
const fixed = broken.replace(/'/g, '"');
const obj = JSON.parse(fixed);

Online Fix

For a quick browser-based repair without writing any code, AI JSONMedic automatically detects and fixes single quotes, trailing commas, Python booleans (True/False/None), and other common JSON errors.

Summary

Scenario	Fix
Python dict → JSON	Use json.dumps()
Python dict string	Use ast.literal_eval() then json.dumps()
LLM / production pipeline	Use json-repair library
JavaScript	Use JSON.stringify()
Quick one-off repair	AI JSONMedic