JSON Validator | Validate & Debug JSON Syntax
Validate JSON syntax in real time and pinpoint mistakes by exact line and column—catch trailing commas, unclosed braces/brackets, unquoted keys/strings, invalid escapes, and duplicate keys. Fast, private, and 100% in-browser.
How to Use This Tool
- 1
Paste or type your JSON into the input area.
- 2
Use Live mode for instant validation or Manual mode to click “Validate”.
- 3
If invalid, read the message with the exact line and column to fix.
- 4
Correct the issue and see results update automatically.
- 5
Copy or use the validated JSON in your project.
Use Cases & Examples
API Development & Debugging
Paste API requests/responses to catch malformed JSON before clients break.
Configuration File Validation
Verify package.json, tsconfig.json, and other config files before commit or deploy.
Data Validation & QA
Check imported/exported JSON for serialization or encoding issues.
Learning JSON Syntax
Practice writing valid JSON with instant feedback and error locations.
JSON Syntax & Validation (RFC 8259)
JSON (RFC 8259) requires double-quoted keys/strings, escaped control characters, no comments, and no trailing commas.
The validator uses a compliant parser and maps exceptions to line/column positions with actionable messages.
All validation runs client-side for speed and privacy.
Frequently Asked Questions
Q.What JSON syntax errors can this validator detect?
A. All RFC 8259 syntax violations including trailing commas, unclosed braces/brackets, unquoted keys/strings, invalid escapes, duplicate keys, unexpected tokens, and more.
Q.Does this tool format or beautify JSON? How is it different from a JSON Formatter?
A. No. This tool focuses on syntax validation only. For pretty-printing or minifying, use a JSON formatter.
Q.Can this validator handle very large JSON files? Any size limits?
A. Yes—within browser memory limits. Inputs up to a few megabytes typically validate instantly; very large files may benefit from Manual mode.
Q.What's the difference between JSON and JavaScript objects?
A. JSON is a strict text format (RFC 8259). JavaScript objects are runtime structures that can include types not allowed in JSON (e.g., functions, undefined, Symbols).
Related Tools
Explore more developer tools
JSON Formatter & Validator | Format, Minify, Validate
Format, validate, and minify JSON with instant error highlights—fully local.
JSON ↔ YAML Converter | Instant Bidirectional Conversion
Instantly convert JSON ↔ YAML with validation and clean formatting. 100% private, runs in your browser.
JSON to TypeScript Converter | Interfaces & Types
Convert JSON to TypeScript interfaces or types with smart inference—runs locally in your browser.
SQL Formatter | Format & Beautify SQL Queries
Beautify SQL with indentation, line breaks, and uppercase keywords. Supports all major dialects—runs locally for privacy.