Fix Invalid JSON with the Validator

JSON is strict — a single misplaced comma or missing quote breaks the whole file. The JSON Validator goes beyond "invalid JSON" by telling you exactly what's wrong, where it is, and how to fix it.

🚩 The Problem

You receive a JSON file from a colleague or an API export tool and it fails to parse:

SyntaxError: Unexpected token } in JSON at position 247

That error message tells you almost nothing. The Validator does better.

🛠️ Step-by-Step

1. Open the JSON Validator.
2. Paste your JSON or upload a .json file.
3. The validator immediately shows:
   • ✅ Valid — your JSON is well-formed and ready to use.
   • ❌ Invalid — with a detailed error report.

📍 Reading the Error Report

For each error, the Validator shows:

Field	Description
Line	Exact line number of the problem
Column	Exact character position on that line
Error type	e.g. "Trailing comma", "Unexpected token"
Suggestion	A plain-English fix recommendation

Example output:

Line 14, Column 3 — Trailing comma before closing brace
  Suggestion: Remove the comma after the last property.

🔧 Common Issues the Validator Detects

Issue	Example	Fix
Trailing comma	{"a": 1,}	Remove the last comma
Single quotes	{'key': 'value'}	Use double quotes
Comments	// this is a note	Remove all comments
Unquoted keys	{key: "value"}	Quote the key: "key"
Missing comma	{"a": 1 "b": 2}	Add comma between properties
Unclosed string	{"name": "Alice}	Close the string with "

📊 JSON Statistics

Even for valid JSON, the Validator displays useful metadata:

• Line count — total number of lines in the file.
• File size — in bytes and KB.
• Key count — total number of properties across all objects.
• Nesting depth — maximum depth of the structure (useful for detecting over-engineered schemas).

💡 Workflow: Validate Before Processing

Always validate before passing JSON to other tools:

Validator → Fix errors → Editor → Transform Builder → Export

This catches issues early and prevents cryptic failures downstream. The Validator is especially useful after:

• CSV/Excel exports that add BOM characters or malformed escaping.
• Manual edits where trailing commas are easy to accidentally add.
• API responses from servers that return non-standard JSON.

🔗 From Validator to Editor

Once errors are identified, click Open in Editor to jump directly to the Monaco-powered JSON editor with the error location highlighted. Fix it and the editor validates in real time.

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🚀 Try it now

Paste any JSON — valid or not — into the JSON Validator to see its structure stats and catch any hidden errors.