JSON Validator

Paste JSON to check whether it is valid. Errors are reported with line, column and a plain-English explanation, the line is highlighted, and Repair fixes the most common mistakes in one click.

Indentation

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How to validate JSON

Paste the JSON or open a file. Validation runs automatically while you type.
A green “Valid JSON” message with statistics means the document is correct. Otherwise read the error: it names the line, the column and what was expected there.
Fix the highlighted line or click Repair, then Format the result to make it easy to read.

Common JSON errors and how to fix them

Error	Example	Fix
Trailing comma	`[1, 2, ]`	Remove the comma before `]` or `}`
Single quotes	`{'name': 'Ada'}`	Use double quotes: `{"name": "Ada"}`
Unquoted key	`{name: "Ada"}`	Quote the key: `{"name": "Ada"}`
Missing comma	`{"a": 1 "b": 2}`	Add a comma between the properties
Comment	`// settings`	JSON has no comments – remove them
Line break in a string	`"line 1⏎line 2"`	Write `\n` instead of a real line break
Invalid value	`undefined`, `NaN`, `True`	Use `null`, a number, `true` or `false`
Leading zero	`{"zip": 01234}`	Write `1234`, or keep it as text: `"01234"`
Missing bracket	`{"a": [1, 2}`	Close every `[` with `]` and every `{` with `}`

What makes JSON valid

JSON is defined in RFC 8259. A valid document follows a few strict rules:

It contains exactly one top-level value, usually an object {} or an array [].
Object members are "key": value pairs separated by commas; keys are always strings in double quotes.
Strings use double quotes; inside them only \" \\ \/ \b \f \n \r \t and \uXXXX escapes are allowed.
Numbers are decimal: no leading zeros, no + sign, no hexadecimal, no NaN or Infinity.
true, false and null are written in lowercase.
Spaces, tabs and line breaks are allowed between tokens, but not comments.

Validate JSON on the command line

Python: python -m json.tool file.json prints the line and column of the first error.
jq: jq empty file.json exits with an error message if the file is invalid.
Node.js: node -e "JSON.parse(require('fs').readFileSync('file.json', 'utf8'))"

Frequently asked questions

What is the difference between a JSON validator and a JSON linter?

A validator checks whether text follows the JSON syntax. A linter usually also enforces a consistent style. This JSON checker validates strictly against RFC 8259 and, with Format, gives you consistent indentation as well.

Can it validate against a JSON Schema?

This page checks syntax. To describe the expected structure of your data, create a schema from an example document with our JSON Schema generator.

Why is my JSON valid here but rejected by another program?

Programs often expect a specific structure (certain keys or types), a particular encoding such as UTF-8 without a byte order mark, or numbers within a limited range. Syntactically valid JSON can still break such application rules.

Is JSON with comments (JSONC) valid?

No. Standard JSON does not allow comments. Some editors accept them in settings files (JSONC), but APIs and JSON.parse do not. Repair removes comments for you.