Fix JSON Broken by Copy-Paste

Copied from a .js file via a plain-text editor, so quotes stayed straight. Two passes fully repair it.

Pasted:
{ 'env': 'prod', 'retries': 3, }

Fixes applied (2):
✓ Replaced single quotes with double quotes
✓ Removed trailing commas

Banner: Fixed & valid JSON

Output:
{
  "env": "prod",
  "retries": 3
}

DevTools printed an object literal with unquoted keys and an undefined. Three passes fix it; the undefined pass is string-aware, so the word 'undefined' inside any string value is left untouched.

Pasted:
{ id: 7, name: 'a', deleted: undefined }

Fixes applied (... up to 3):
✓ Replaced single quotes with double quotes
✓ Added quotes to unquoted object keys
✓ Replaced undefined with null

Banner: Fixed & valid JSON

A messaging app reflowed the text and dropped the comma between objects. The missing-comma pass restores it.

Pasted:
[
  { "a": 1 }
  { "a": 2 }
]

Fixes applied (1):
✓ Added missing commas between elements

Banner: Fixed & valid JSON

Pasted from a Word doc, the quotes are curly. This fixer won't convert them, so it reports invalid. Replace the curly quotes in your editor, then re-run.

Pasted (curly quotes — look normal, aren't):
{ “name”: “widget” }

Fixes applied (0)
Banner: Partially fixed — output may still have issues

Fix first (in your editor):
  Find “ and ”, replace with "
Then re-run → valid.

Email rich-text dropped the backslash from an escape sequence. The fixer can't infer where backslashes belonged, so it can't restore them. Re-copy from a plain-text source.

Pasted (backslash before n was stripped):
{ "path": "C:Users
ame" }

Fixes applied (0)
Banner: Partially fixed

Why: the original was "C:\\Users\\name". The fixer cannot
know which characters lost a preceding backslash.
Fix: re-copy the JSON from a code block / plain-text source.

The most common copy-paste corruption and the one this fixer does NOT handle. Only straight ' quotes are converted; “ ” ‘ ’ survive and break parsing. They're invisible in many fonts, so the text looks fine. Find-replace the curly quotes to straight ones in your editor first, then run the fixer for the remaining issues.

When a rich-text channel strips backslashes, "line\nbreak" becomes "linenbreak" and "a\"b" loses its escape. The fixer cannot infer where backslashes belonged, so this is unrecoverable here. Re-copy the JSON from a plain-text or code-block source where the backslashes survived.

Word and macOS turn - into —/– in some contexts. A negative number like -5 becoming —5 is invalid JSON, and the fixer doesn't normalize dashes. Replace —/– with - in your editor before fixing.

Paste from rendered HTML can insert NBSP where a normal space was. The fixer doesn't normalize whitespace beyond what JSON.parse ignores, and NBSP is not JSON whitespace, so it can break parsing in odd spots. Find-replace NBSP → regular space in your editor.

The undefined pass is string-aware: it tracks string state while walking the snippet, so a string reading "value undefined" is left exactly as-is. Only a bare undefined value is rewritten to null. Pasted prose is never altered, so no review of string fields containing the word undefined is needed after fixing.

A value like 'it's here' defeats the value-quote pass ('[^']*' stops at the inner apostrophe), producing broken output. This is common in prose pasted from a document. Switch those quotes to double quotes by hand.

If the paste preserved everything (you copied from a code block or plain-text editor), the JSON parses on first try — No fixes needed — and you get it cleanly re-indented. The cleanest paste path: always copy JSON from a monospace/code context.

Partial corruption — some quotes curly, some straight — happens when only part of the text passed through a rich-text app. The fixer converts the straight single quotes and leaves the curly ones, so the result is still invalid. Normalize all curly quotes first, then run the fixer.

Free tier caps at 2 MB. A paste that large is unusual; if you hit it, you're probably pasting a whole file's worth of data — drop the file directly instead, and consider Pro (100 MB) for big payloads.