JSON Formatter & Validator
Your data is 100% private! Formatting and validation run in your browser. Your JSON is never sent to our servers. Paste your JSON below, or a URL that returns it, to format it and check it against the spec you pick.
About
Crushed into a single line, an extra comma hanging around, quotes missing from a key. If you’ve ever wasted time hunting down that kind of thing by hand, that’s exactly why this site exists. Paste your JSON here (or drop in a URL and we’ll fetch the content for you) and, in less than a second, it comes back properly formatted, with real indentation and syntax highlighting.
Validation comes along with it. The tool checks your JSON against whichever spec you choose (RFC 8259, 7159, 4627, ECMA-404, or JSON5) and, when something breaks, it points to the exact line with the error instead of just saying the JSON is invalid. You can also change the indentation to 2, 3, or 4 spaces, use a tab, or compress everything to minify it, and the session history keeps what you’ve already processed, so it’s easy to compare before and after. For large payloads, you can even collapse nested nodes and focus only on the part you care about.
Everything runs right in your browser, without sending anything to any server. No sign-up, no limits. Paste it in, process it, copy the result, and get back to what actually matters.
Learn
Most JSON errors look cryptic until someone actually explains them. The posts below break down the ones you’ll really run into: the trailing comma that kills a parse, the key without quotes, that stray token the validator points at but never bothers to explain. They’re grouped by category, so you can jump straight to whatever is biting you right now.
Concepts
- What Is JSON? A Beginner’s Guide
- JSON vs XML: When to Use Each One
- JSON vs YAML: Practical Differences
- What Is JSON Schema and How to Validate Your Data
- JSONPath: How to Query Data in JSON (With Examples)
- What Is JSON Lines (JSONL) and When to Use It
Errors and Solutions
- Unexpected Token in JSON at Position 0: How to Fix It
- SyntaxError: JSON.parse: Unexpected Character: How to Fix It
- Trailing Comma in JSON: What It Is and How to Fix It
- JSON.parse: Unexpected End of JSON Input: How to Fix It
- Unexpected Non-Whitespace Character After JSON: How to Fix It
- Why Is My JSON Invalid? Full Checklist
- Single vs Double Quotes in JSON: Why It Matters
- The 10 Most Common JSON Errors (and How to Spot Each One)
Glossary
- What Is a JSON Object
- What Is a JSON Array
- JSON Data Types (string, number, boolean, null, object, array)
- JSON Syntax: Quick Reference Guide
- What Is Data Serialization and Deserialization
Practical Use Cases
- How to Use JSON in REST APIs
- Understanding package.json From Scratch
- What Is tsconfig.json and What It’s For
- How to Structure JSON Configuration Files
- JSON Web Token (JWT): How the Payload Works
Tutorials
- How to Parse JSON in Python (With Examples)
- JSON.parse vs JSON.stringify in JavaScript: The Complete Guide
- Working With JSON in PHP: json_encode, json_decode, and Common Errors
- Reading and Writing JSON in Java With Jackson
- JSON in Java With Gson: A Practical Guide
- Working With JSON in Node.js
- JSON in C#: System.Text.Json vs Newtonsoft.Json
- Working With JSON in Go (encoding/json)
- JSON in Ruby: JSON.parse and to_json in Practice