JSON Validator
Paste your JSON and validate it instantly. Get clear error messages with position information.
Why JSON Validation Is Critical in Development
JSON (JavaScript Object Notation) is the universal data format for APIs, configuration files, databases and web services. A single missing comma, unclosed bracket or misquoted key causes a parsing error that can crash applications, fail API calls or produce silent data corruption. Our JSON Validator instantly detects syntax errors with precise error messages — it also formats and minifies JSON, making it a daily companion for developers, data engineers and anyone working with APIs.
Frequently Asked Questions
What causes a JSON validation error? ▼
Common JSON errors: (1) Missing or extra comma (trailing comma is invalid in JSON), (2) Unquoted keys — keys must always be in double quotes, (3) Single quotes instead of double quotes, (4) Undefined, NaN or Infinity values (not valid in JSON), (5) Unclosed brackets { } or [ ], (6) Comments — JSON does not support // or /* */ comments.
What is the difference between JSON and JSON5? ▼
JSON is the strict standard (RFC 8259) used by APIs and databases — no comments, no trailing commas, only double quotes. JSON5 is an extension that allows comments, trailing commas and single quotes — used in some configuration files (like VS Code settings.json). Our validator checks standard JSON.
How to validate JSON in JavaScript? ▼
Use try/catch with JSON.parse(): try { const obj = JSON.parse(jsonString); } catch(e) { console.error("Invalid JSON:", e.message); } For production, consider using the Zod or Joi libraries for schema validation beyond just syntax checking.
What is JSON schema validation? ▼
JSON schema validation checks not just syntax but structure — whether fields are the correct type, required fields are present, values are within allowed ranges. For schema validation, use our Schema Generator tool or libraries like Ajv (JavaScript), jsonschema (Python) or everit-json-schema (Java).
How to fix "Unexpected token" JSON error? ▼
Unexpected token errors usually mean: a character that should not be there (like a curly quote " instead of straight quote "), a missing comma between elements, or a trailing comma after the last item in an object or array. Paste your JSON into our formatter — it highlights the exact location of the error.
Is JSON case-sensitive? ▼
Yes. JSON keys and string values are case-sensitive. "Name", "name" and "NAME" are three different keys. Boolean values must be lowercase: true, false (not True, False). null must be lowercase (not NULL or Null).