JSON Formatter & Validator
Text ToolsPaste a JSON string and click Format to get a nicely indented and highlighted output. Use Minify to compress, or Sort Keys to alphabetize object keys.
Result:
JSON Format Guide
JSON Syntax Reference
JSON (JavaScript Object Notation) supports six data types. All JSON data must be one of these types, and strings must use double quotes.
| Type | Syntax |
|---|---|
| Object | { "key": value } |
| Array | [ value, ... ] |
| String | "text" |
| Number | digits |
| Boolean | true / false |
| Null | null |
Common Use Cases
JSON formatting and validation is essential across many development workflows.
- API development — Inspect and debug API responses by formatting raw JSON payloads.
- Configuration files — Format package.json, tsconfig.json, and other config files for readability.
- Data transformation — Verify the output of CSV-to-JSON or XML-to-JSON conversions.
- Log analysis — Pretty-print structured JSON logs for easier debugging.
Tips
- Use Minify to strip whitespace and reduce file size for production deployments.
- Sort Keys alphabetizes object keys, making JSON easier to compare with diff tools.
- Error messages show the position of syntax errors so you can fix them quickly.
- Trailing commas are invalid in JSON (unlike JavaScript) — remove them before formatting.
Glossary
- JSON (JavaScript Object Notation)
- A lightweight, text-based data interchange format derived from JavaScript. It is language-independent and widely used for APIs, configuration files, and data storage. Defined by RFC 8259.
- JSON Schema
- A vocabulary for annotating and validating JSON documents. It defines the structure, data types, and constraints of JSON data, enabling automated validation of API requests and responses.
- RFC 8259
- The IETF standard that defines the JSON data interchange format. It specifies syntax rules such as requiring double quotes for strings and prohibiting trailing commas.
- Minification
- The process of removing all unnecessary whitespace, line breaks, and indentation from JSON (or other code) to reduce file size. Minified JSON is functionally identical to formatted JSON.
- Trailing Comma
- A comma placed after the last element in an object or array. While allowed in JavaScript and some other languages, trailing commas are invalid in the JSON specification and will cause a parse error.
Frequently Asked Questions
- Q: Is my data safe when using this tool?
- A: Yes. All processing is done entirely in your browser using JavaScript. Your JSON data is never sent to any server.
- Q: What is the difference between Format and Minify?
- A: Format adds indentation and line breaks for readability. Minify removes all unnecessary whitespace to produce the most compact representation, which is useful for reducing payload size.
- Q: Why do I get a trailing comma error?
- A: The JSON specification (RFC 8259) does not allow trailing commas after the last element in an object or array. While JavaScript allows them, you must remove trailing commas for valid JSON.
- Q: Does Sort Keys change array order?
- A: No. Sort Keys only reorders object keys alphabetically. Array element order is preserved because order is significant in JSON arrays.