What kinds of malformed input can this fix?

It targets three common issues: single-quoted strings (Python-dict style), curly or "smart" quotes pasted from a word processor, and bare/unquoted object keys (JS-object-literal style). It handles any combination of these three at once.

Is this guaranteed to always produce valid JSON?

No, it's explicitly heuristic and best-effort, not a full JSON5/JS parser. Things outside its scope, trailing commas, comments, or genuinely malformed structure, will still fail, and the tool reports the underlying parse error clearly when that happens rather than pretending to succeed.

How does it decide which quote characters are string delimiters vs. apostrophes?

It scans character by character: any ' or " it encounters is treated as opening a string, which continues (honoring backslash escapes) until the matching closing quote of the same character. This means a genuine apostrophe inside a double-quoted string is left alone, since only the delimiter quote character ends that string.

What happens to escaped quotes during conversion?

An escaped \' becomes a plain ' once the string is re-delimited with double quotes (since ' no longer needs escaping), and any literal " found inside a string's content gets escaped to \" so it doesn't prematurely terminate the new double-quoted string.

Fix JSON Quotes Online - Repair Single/Curly Quotes and Bare Keys

Overview

Introduction

JSON-like text copied from Python dicts, JS source, or a word processor often uses single quotes, smart quotes, or unquoted keys, none of which JSON.parse accepts.

This tool attempts an automatic, best-effort repair so you don't have to fix every quote by hand before it will parse.

What Is JSON Quote Fixer?

A heuristic text repair pass that runs three transformations in sequence: straighten curly/smart quotes, convert every quoted string (single or double delimited) to a properly escaped double-quoted string, and add double quotes around bare identifier-like object keys.

After repair, the result is validated with a real JSON.parse and pretty-printed; if it still doesn't parse, the tool reports that clearly along with the underlying parse error.

How JSON Quote Fixer Works

First, curly quotes (‘ ’ “ ”) are replaced with their straight ASCII equivalents. Then a character scan converts every string, whether delimited by ' or ", into a double-quoted string, escaping internal double quotes and un-escaping now-unnecessary \' sequences.

Finally, another character scan (that skips over already-quoted string content) applies a regex to text runs outside of strings, adding double quotes around any bare identifier-like key immediately followed by a colon. The repaired text is then run through JSON.parse; success re-serializes it pretty-printed, failure returns the parse error with an explanation that auto-fix couldn't fully repair it.

When To Use JSON Quote Fixer

Use it when you've copied a Python dict literal, a JS object literal, or word-processor text with smart quotes and need it to become real JSON quickly.

It's also a fast first pass before manually fixing anything the automatic repair couldn't handle.

Often used alongside JSON Single Quote Converter, JSON Double Quote Converter and JSON Syntax Changer.

Features

Advantages

Handles single quotes, curly quotes, and unquoted keys together in one pass, not just one issue at a time.
Correctly escapes and un-escapes quote characters during delimiter conversion, rather than a naive find-and-replace that would break on embedded quotes.
Falls back to a clear, honest error (including the real parse error) rather than silently producing broken output.

Limitations

This is heuristic, not a full JSON5/JS parser; trailing commas, comments, and other JS-only syntax are out of scope and will still fail.
The bare-key regex expects an identifier-like key immediately followed by a colon; unusual key formatting may not be detected correctly.

Examples

Fixing single quotes and a bare key

Input

{name: 'Ada', 'age': 30}

Output

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

The bare key name gets quoted, and both single-quoted strings become double-quoted.

Input auto-fix can't fully repair

Input

{not: valid: at: all[[[

Output

Error: Auto-fix couldn’t fully repair this input: Unexpected token 'v', "{"not": valid: at:"... is not valid JSON

The structure itself is broken (extra colons, unmatched brackets), which is beyond what quote/key repair can fix, so the underlying parse error is surfaced directly.

Best Practices & Notes

Best Practices

Treat the output as a starting point for genuinely malformed input, not a guaranteed final answer.
If you know the input is single-quoted throughout with no unquoted keys, JSON Double Quote Converter is a more predictable, narrower tool.
Re-run JSON Validator on the result if you need certainty the fix fully succeeded.

Developer Notes

The quote-delimited-string scan and the bare-key regex pass are deliberately separate steps run in sequence, rather than one combined regex, because correctly distinguishing "inside a string" from "outside a string" requires actual character-by-character scanning (tracking the current delimiter and escape state), something a single regex can't reliably do across arbitrary nested quote styles.

JSON Quote Fixer Use Cases

Converting a Python dict literal (single-quoted) pasted into a JSON field back into valid JSON
Cleaning up JSON-like text pasted from a word processor with smart quotes
Quickly repairing a hand-written JS-object-literal snippet into strict JSON for an API

Common Mistakes

Assuming this will fix any malformed JSON; it only targets quote style and key quoting, not structural issues like trailing commas or mismatched brackets.
Not reading the reported parse error when repair fails; it usually points precisely at what's still wrong after the automatic fixes were applied.

Tips

If repair fails, try removing trailing commas and comments by hand first, then re-run this tool.
For predictable, narrower single-quote-to-double-quote conversion without key repair, JSON Double Quote Converter is more precise.

JSON Quote Fixer