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JSON Parse Error Helper

DiagnosticFreePrivateBrowser-only

Paste broken JSON to locate syntax issues, understand common parse errors, and generate valid formatted output instantly. Great for unexpected token and SyntaxError problems.

  • Detect syntax mistakes
  • Fix unexpected token errors
  • Format valid output
  • Private browser processing
JSON input

Paste JSON that caused a parse error.

Result
Ctrl+Enter Find & Fix Errors  ·  Ctrl+Shift+M Minify

JSON Parse Error: Fix Unexpected Token Online

Resolve JSON parse errors instantly. Paste broken JSON to understand syntax problems like unexpected token, missing quotes, trailing commas, or incomplete objects, then generate valid output.

What the Error Messages Mean

Unexpected Token
Usually caused by commas, invalid characters, or broken structure near the reported position.
Unexpected End of Input
Your JSON likely ends too early or misses closing brackets or braces.
Expected Property Name
Object keys must be double-quoted strings in strict JSON.
Unexpected String
Often caused by missing commas between fields or malformed structure.

How to Use

  1. Paste broken JSON.
  2. Click Find & Fix Errors (or press Ctrl+Enter).
  3. Read the line, column, and plain-English explanation.
  4. Copy corrected JSON from the result panel.

Common Causes

  • Trailing commas
  • Missing quotes around keys or strings
  • Missing commas between properties
  • Broken or mismatched braces
  • Comments in JSON (not allowed in strict JSON)
  • Partial or truncated copied data

Features

  • Parse error guidance in plain language
  • Format corrected JSON with your chosen indent
  • Browser-only private processing
  • Mobile-friendly layout and sticky actions
  • Helpful examples in the sections below
  • Fast debugging workflow with Validate and Minify

Every Common Parse Error, Fixed

Missing comma between properties
{ "a": 1 "b": 2 }
→ Fix
{ "a": 1, "b": 2 }
Trailing comma after last item
{ "a": 1, "b": 2, }
→ Fix
{ "a": 1, "b": 2 }
Unquoted keys
{ name: "Alice", age: 30 }
→ Fix
{ "name": "Alice", "age": 30 }
Single-quoted strings
{ 'name': 'Alice' }
→ Fix
{ "name": "Alice" }
Comment inside JSON
{ "a": 1 // comment
}
→ Fix
{ "a": 1 }
Unclosed brace or bracket
{ "a": [1, 2, 3 }
→ Fix
{ "a": [1, 2, 3] }

Quick Rules to Prevent Parse Errors

  • All keys must be double-quoted strings: "key", not key or 'key'
  • All string values must use double quotes: "value", not 'value'
  • Separate every property and array item with a comma: but not after the last one
  • No comments: // and /* */ are not valid JSON syntax
  • No trailing commas: { "a": 1, } is invalid
  • No undefined, functions, or NaN: only string, number, boolean, null, object, array

Frequently Asked Questions

Is this free?

Yes. No sign-up required.

Is my JSON uploaded?

No. Everything runs locally in your browser.

What is a parse error?

It means the text fails strict JSON rules—often commas, quotes, or brackets—so JSON.parse throws a SyntaxError.

What does unexpected token mean?

The parser met a character or value where JSON grammar does not allow it; the tool shows where and suggests what to check.

Can this fix trailing commas?

This page pinpoints the error. For automatic cleanup, use Fix Invalid JSON or JSON Repair.

Why does JSON need double quotes?

The JSON specification requires double quotes for keys and string values.

Does it work on mobile?

Yes. Editors and the sticky action bar are optimized for small screens.

Can I copy corrected JSON?

Yes—from the result panel or the mobile sheet after a successful format or minify.

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