Introducing JSON Validator | Tools.Town Blog

JSON Validator is now live on Tools.Town — a focused tool that checks your JSON for syntax errors, reports the exact line and character position of each problem, and shows the successfully parsed structure when the JSON is valid.

Paste your JSON and know immediately whether it’s valid — and if not, exactly why.

What Does It Do?

Syntax Check

Validates JSON against the RFC 8259 specification. Catches trailing commas, bad quotes, unclosed brackets, and more.

Error Location

Points to the exact line and character where the error occurs — no more hunting through a 500-line blob.

Parsed Tree

When valid, shows the parsed JSON structure as a collapsible tree — making it easy to explore deeply nested data.

Common gotchas: trailing commas after the last item, single-quoted strings, and JavaScript-style comments — none of these are valid JSON.

How It Works

Paste JSON

Paste any JSON string — from an API response, a config file, or a log entry.

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See validation

A green 'Valid' badge or a red error message with the exact position appears instantly.

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Explore tree

Browse the parsed tree to inspect structure and values without scrolling through raw text.

Why We Built It

JSON errors in API integrations and config files are common, and the error messages from most parsers are unhelpful — just “unexpected token at position 847”. JSON Validator maps that to a line number with a human-readable explanation, cutting debug time from minutes to seconds.

Try It Now

Free Tool

No sign-up In-browser

JSON Validator

Check JSON syntax, get exact error positions, and explore the parsed tree. Instant and in-browser.

Syntax validationError line numbersParsed tree viewSchema validation

Validate JSON

Related: JSON Formatter to also beautify valid JSON, and JSON to CSV for data conversion.

Frequently Asked Questions

What's the difference between JSON Validator and JSON Formatter?

JSON Formatter beautifies valid JSON. JSON Validator specifically checks for syntax errors and tells you exactly what went wrong — trailing commas, missing brackets, unquoted keys, etc.

Does it validate against a JSON Schema?

Basic syntax validation is built in. JSON Schema validation (checking structure and types against a schema) is available in advanced mode.

What are the most common JSON syntax errors?

Trailing commas (not allowed in JSON), single quotes instead of double quotes, unquoted keys, missing commas between elements, and unclosed brackets are the most frequent issues.

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Introducing JSON Validator — Now Live on Tools.Town