What does a JSON validator check?

It checks whether the input is strict JSON that can be parsed, including quote rules, missing commas, trailing commas, bracket balance, and invalid values.

Can it validate JSON with trailing commas or single quotes?

Strict JSON does not allow trailing commas or single-quoted strings. The validator flags those patterns so the payload can work with standard parsers.

Is this the same as JSON Schema validation?

No. This page checks syntax first. Use a JSON Schema tool after syntax passes when you need required fields, types, enums, or shape validation.

What should I do after JSON is valid?

Format the payload for review, compare it against another response, generate TypeScript types, or use it in an API request workflow depending on the next task.

JSON Validator With Syntax Error Explanations

Validate strict JSON syntax, locate parser errors, and review the likely explanation before using the payload.

✗

Invalid JSON

Error: Unexpected token ']', ..."": 1 }, ], "tota"... is not valid JSON

Location: line 6, column 41

    { "sku": "pro-plan", "quantity": 1 },
                                        ^

Likely fixes

Remove trailing commas before closing braces or brackets.

JSON Input

Validator Error Checks

JSON validator error fixes start with the first question in any JSON workflow: can this text be parsed as strict JSON? Use this page before formatting an API body, comparing responses, generating types, creating schemas, or pasting payloads into request tools.

Common Errors It Catches

The most frequent failures are missing commas, trailing commas copied from examples, single-quoted strings, unquoted object keys, comments from JSONC files, unclosed brackets, and invalid values such asundefined, NaN, or Infinity.

Common JSON parse errors and fixes

Trailing comma

Unexpected token near ] or } after the final item.

Remove the comma after the last property or array value.

Single quotes

A parser stops at a key or string wrapped in apostrophes.

Use double quotes for every JSON key and string value.

Unquoted key

The error points at a property name before a colon.

Wrap the property name in double quotes before validating again.

JSONC comment

The input includes // or /* */ notes copied from config files.

Remove comments before sending the value to a strict JSON parser.

Invalid value

undefined, NaN, or Infinity appears in the input.

Replace it with null, a quoted string, true/false, or a valid number.

Unclosed structure

The parser reaches the end while still inside an object or array.

Close the missing bracket or brace, then format the payload.

After Syntax Passes

Syntax validity does not prove the payload matches an API contract. Once it parses, format it with the JSON Formatter, compare versions with JSON Compare, or generate client models with JSON to TypeScript.

Sensitive Payloads

Validation runs in the browser, but pasted examples can still appear in your screen, clipboard, browser memory, or shared device history. Replace tokens, secrets, customer identifiers, and production-only values before testing a payload.

Questions about this tool

What does a JSON validator check?: It checks whether the input is strict JSON that can be parsed, including quote rules, missing commas, trailing commas, bracket balance, and invalid values.
Can it validate JSON with trailing commas or single quotes?: Strict JSON does not allow trailing commas or single-quoted strings. The validator flags those patterns so the payload can work with standard parsers.
Is this the same as JSON Schema validation?: No. This page checks syntax first. Use a JSON Schema tool after syntax passes when you need required fields, types, enums, or shape validation.
What should I do after JSON is valid?: Format the payload for review, compare it against another response, generate TypeScript types, or use it in an API request workflow depending on the next task.