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Advanced JSON Fixer & Recovery Engine

Paste → Instant fix. Repair malformed JSON, recover truncated payloads, extract from logs, fix AI/API output — 100% client-side. Fix trailing commas, missing quotes, broken arrays, AI-generated JSON.

100% in-browserNo signupFree forever

Advanced JSON Fixer & Recovery Engine

Paste → Instant fix. Repair malformed JSON: trailing commas, missing quotes, broken arrays, AI-generated JSON — 100% client-side

Repair options

Fix from API error

Paste an error like "Unexpected token } in JSON at position 245" to highlight the position.

or paste JSON below

JSON Input

1
1

Fixed JSON Output

Fixed JSON will appear here...

JSON Fixer Features

Automatic Error Detection

Scans and identifies all JSON syntax errors automatically

Smart JSON Repair

Fixes common errors like trailing commas, single quotes, and unquoted keys

Precise Error Location

Shows exact line and column numbers for each error

Visual Error Highlighting

Highlights problematic lines with color-coded indicators

Learn More About JSON Fixing

10 Most Common JSON Mistakes Developers Make

Learn about the most common JSON mistakes and how to fix them instantly with examples.

Read Guide →

25 Broken JSON Examples and How to Fix Them

Real-world broken JSON examples with step-by-step fixes and explanations.

Read Guide →

Why JSON Breaks in Real-World APIs

Understand why APIs return broken JSON in production and how to fix it effectively.

Read Guide →

How JSON Fixers Work Internally

Learn how JSON fixers work internally and why manual fixing often fails.

Read Guide →
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AI JSON FixerAI-powered JSON error fixFix JSON Comma/BraceFix comma/brace JSON errorsFix Broken JSONRepair broken JSON onlineFix Control Char JSONFix invalid control charsFix JSON Parse ErrorFix JS JSON.parse errorsAll tools

What Is a JSON Fixer?

A JSON fixer is a tool that automatically detects and repairs common JSON syntax errors so you do not have to hunt through hundreds of lines by hand. JSON is strict — even a single misplaced comma, a single-quoted string, or an unquoted key will preventJSON.parse() from working and crash the application reading the data.

Broken JSON shows up everywhere in real development: AI models produce JSON with trailing commas or comments, APIs sometimes return malformed responses, config files get edited by hand and pick up errors, and copy-pasting JavaScript object literals brings in single quotes and unquoted keys. This tool handles all of those cases — paste broken JSON and get valid, parseable output in one click.

How it works

Fix Broken JSON in Seconds

01

Paste your broken JSON

Type or paste any invalid JSON, including minified payloads, API responses, AI output, or JavaScript object literals.

02

See errors highlighted

The tool immediately flags every syntax error with the exact line and character position, so you know what is wrong.

03

Auto-fix applies

Click Fix to automatically repair trailing commas, single quotes, unquoted keys, missing brackets, and other common errors.

04

Copy fixed JSON

Copy the repaired JSON to your clipboard or download it — ready to paste back into your code, config, or API request.

Common JSON Errors and How to Fix Them

The table below covers the most frequent JSON syntax errors developers encounter and how the fixer handles each one.

ErrorExample (broken)Fix applied
Trailing comma{"a":1,"b":2,}Remove the comma before the closing brace or bracket
Single quotes{'key':'value'}Replace single quotes with double quotes
Unquoted keys{key: "value"}Wrap the key in double quotes
Missing quotes on string value{"name": Alice}Wrap the value in double quotes
Unexpected token{"x": undefined}Replace undefined/NaN/Infinity with null or a valid value
Unterminated string{"msg": "helloClose the string and any open brackets
Use cases

When You Need a JSON Fixer

🐛

Debug API Responses

Fix malformed JSON returned by third-party APIs that breaks your application at runtime.

⚙️

Fix Config Files

Repair hand-edited JSON config files where trailing commas or missing quotes slipped in.

📦

Repair Exported Data

Clean up JSON exports from databases, spreadsheets, or tools that produce non-standard output.

🔧

Fix JS Object Literals

Convert JavaScript object literals — with single quotes and unquoted keys — into valid JSON.

🕸️

Clean Scraped JSON

Repair JSON extracted from web pages or logs that contains extra text, comments, or broken nesting.

📋

Fix Copy-Paste Errors

Recover JSON that was copy-pasted from documentation, Slack, or emails and lost its formatting.

FAQ

Frequently Asked Questions

1How do I fix invalid JSON?
Paste your broken JSON into this tool and click Fix. The fixer automatically detects and repairs trailing commas, single quotes, unquoted keys, and missing brackets — then returns valid, parseable JSON.
2Why does my JSON work in JavaScript but fail in Python's json.loads()?
JavaScript is more lenient than strict JSON. Trailing commas, single quotes, and unquoted keys work in JS object literals but are invalid JSON and throw JSONDecodeError in Python. Paste your JSON here — the fixer detects and repairs all of these automatically.
3How do I fix a trailing comma in JSON?
JSON does not allow trailing commas. Paste your JSON here and the fixer automatically removes all trailing commas to produce valid output.
4What does "Unexpected token" mean in JSON?
It means the parser found a character it did not expect. This often happens with trailing commas, single-quoted strings, JavaScript comments, or undefined values. Paste your JSON here to auto-fix most of these cases.
5Is my JSON sent to a server?
No. All fixing runs entirely in your browser. Your JSON is never uploaded or stored anywhere — safe for API keys, tokens, and production payloads.
6My API response passes json.loads() but my application crashes — why?
Syntax is valid but the structure may not match what your code expects — a field is null when your code assumes a string, or a number is wrapped in quotes. Check both syntax and schema with the JSON Validator. Also watch for duplicate keys, which parsers silently resolve by keeping only the last value.
7Can JSON have single quotes?
No. The JSON specification requires all strings to be enclosed in double quotes. Single-quoted strings are valid JavaScript but not valid JSON. This tool automatically converts single quotes to double quotes during the fix.
8How do I fix JSON that contains comments?
Standard JSON does not support comments. This fixer strips // and /* */ comments automatically. If you frequently work with commented JSON, consider using JSONC or JSON5 formats, which natively support comments.
9How do I fix a truncated or incomplete JSON string?
Paste the incomplete JSON here. The fixer attempts to close any open strings, arrays, or objects to produce parseable output. Always review the result manually, as the recovery may not precisely match the original intent.
10How do I fix JSON with unquoted keys?
JSON requires all object keys to be double-quoted. Paste your JSON here and the fixer wraps all unquoted keys in double quotes automatically — useful for JavaScript object literals that need to be converted to strict JSON.
11How do I fix JSON copied from a config file that has comments and trailing commas?
Config files often use JSONC or JSON5 format — both allow // comments and trailing commas, but standard JSON parsers reject them. Paste the config here; it strips comments and removes trailing commas automatically. If you need comment support at runtime, use the jsonc-parser npm package instead.
12How do I find the exact line where a JSON error occurs?
This tool highlights the exact line and character position of each error. In Node.js, JSON.parse() SyntaxError messages include position info. In Python, json.JSONDecodeError includes lineno and colno attributes.
Learn more

Developer Guides

📖Top 10 JSON Errors📖25 Broken JSON Examples📖Fix JSON Errors Guide📖Why JSON Breaks in APIs📖stringify vs parse

Last updated: May 2026

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