How do I validate JSON syntax?

Paste your code into the editor. The tool automatically analyzes the syntax using a recursive descent parser. If there are errors (like missing quotes or braces), they will be highlighted with line numbers.

Can it fix errors automatically?

Our validator is primarily for detection, but it supports 'lax' modes like JSON5 that allow trailing commas and comments, effectively 'fixing' valid JS objects that aren't strict JSON.

What is the difference between JSON and JSON5?

Standard JSON (RFC 8259) is very strict: double quotes required, no comments, no trailing commas. JSON5 is a modern superset that allows comments, single quotes, and trailing commas, making it better for configuration files.

JSON Validator & Linter

Strict & Lenient Modes

Validate your JSON syntax instantly.
Supports **Strict JSON**, **JSON5** (trailing commas), and **JSONC** (comments).

Config

Mode

Lint Rules

No Duplicates

Input JSON

Validation Report

Start typing to validate...

How does a JSON Validator work?

A **JSON Validator** uses a parser algorithm to read your text and ensure it complies with the **JSON Data Interchange Standard (ECMA-404)**. It checks for structural integrity—balanced braces ``, properly quoted keys `"key"`, and correct data types. Advanced validators like ours also act as **Linters**, checking for best practices like avoiding duplicate keys or excessive nesting.

How to Check JSON Syntax

1
Paste Code
Paste your JSON string into the left editor panel.
2
View Report
The tool runs immediately. If the JSON is valid, you'll see a green "Valid" badge. If not, a red error list will show exactly which line and column caused the issue.
3
Switch Modes
If your file has comments (e.g., `tsconfig.json`), switch the mode from **Strict** to **JSONC** to stop the validator from flagging comments as errors.

Advanced Validation

Precise Errors

We don't just say "Unexpected token". We tell you "Expected a comma at line 12, column 34" so you can fix it fast.

Schema Linter

Our engine checks for logical issues like **duplicate keys**, which are technically invalid in many parsers but often ignored by simple checkers.

Private & Secure

Validation happens in a Web Worker on your device. Your sensitive API keys or PII data are never sent to our servers.

JSON Validator & Linter

How does a JSON Validator work?

How to Check JSON Syntax

Paste Code

View Report

Switch Modes

Advanced Validation

Precise Errors

Schema Linter

Private & Secure

Frequently Asked Questions

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