Online JSON Formatter, Validator, and Minifier
JSON (JavaScript Object Notation) has become the standard data format for web APIs, configuration files, and data exchange between systems. Whether you are building a REST API, debugging a webhook payload, or editing a package.json file, working with raw JSON can be frustrating when the data arrives as a single unformatted line. This free online JSON formatter lets you paste any JSON string and instantly format it with proper indentation, validate its structure, or minify it for production use. Everything runs entirely in your browser, so your data never leaves your machine.
Malformed JSON is one of the most common causes of silent failures in web applications. A missing comma, an extra trailing comma, or an unescaped quote character can break an entire API response chain. Instead of scanning through hundreds of lines by hand, use the validator below to pinpoint exactly where the problem is and fix it in seconds.
JSON Formatter & Validator
Paste your JSON to format, minify, or validate it. Entirely client-side.
How to Use This JSON Formatter
Using the tool is straightforward. Paste your raw or minified JSON into the input field. Then choose one of three actions depending on what you need:
Format (Beautify) takes compressed or poorly indented JSON and outputs it with clean, readable indentation. This is especially helpful when you copy a response from a browser’s network tab or from a log file and need to understand its structure quickly.
Minify does the opposite. It strips all unnecessary whitespace and line breaks to produce the smallest possible string. Use this when you need to embed JSON in a URL parameter, store it in a database field, or reduce payload size before sending it over the network.
Validate checks whether your input is syntactically correct JSON. If there is an error, the tool highlights the problem area and provides a description of what went wrong, such as an unexpected token or a missing bracket. Once you are satisfied with the output, click the Copy button to send the result straight to your clipboard.
Key Features
Instant formatting and beautification. Converts minified or messy JSON into a well-indented, human-readable structure using standard two-space indentation. Large payloads with deeply nested objects become easy to scan and understand.
One-click minification. Removes all whitespace and newlines from your JSON to produce the most compact representation. Ideal for reducing file size before transmission or storage.
Validation with clear error messages. Parses the JSON and reports the first syntax error it encounters, including the position and nature of the problem. No more guessing which line has the stray comma.
Copy to clipboard. A single click copies the formatted or minified output so you can paste it directly into your code editor, API client, or terminal without selecting text manually.
Fully client-side processing. Your data is processed entirely in the browser using JavaScript. Nothing is transmitted to a server, which means sensitive configuration data, API keys embedded in test payloads, and private data remain on your machine.
Frequently Asked Questions
What is JSON used for?
JSON is a lightweight data interchange format that is easy for both humans and machines to read and write. It is the dominant format for REST API responses, configuration files for tools like ESLint and Prettier, NoSQL database documents in systems like MongoDB and CouchDB, and front-end state management. Its simplicity and universal language support have made it the default choice over older formats for most modern web development workflows.
How do I validate JSON and find syntax errors?
Paste your JSON into the input field above and click the Validate button. The tool uses the browser’s built-in JSON parser to check the syntax. If the JSON is valid, you will see a confirmation message. If it is invalid, the tool displays the error type and the approximate position in the string where the parser encountered the problem. Common errors include trailing commas after the last item in an array or object, single quotes instead of double quotes around keys, and unescaped special characters inside string values.
What is the difference between JSON and XML?
Both JSON and XML are used to structure and transmit data, but they differ significantly in syntax and weight. JSON uses a compact key-value pair notation with curly braces and square brackets, while XML uses opening and closing tags similar to HTML. JSON files are typically smaller because they avoid the overhead of repeated tag names. Most modern APIs default to JSON because it maps naturally to JavaScript objects and is faster to parse in a browser. XML still appears in legacy SOAP APIs, RSS feeds, and enterprise systems where schema validation through XSD is required.
Can JSON contain comments?
The official JSON specification does not support comments. Any text outside of valid JSON syntax, including lines starting with // or blocks wrapped in /* */, will cause a parse error. This is a deliberate design decision to keep the format simple and unambiguous. If you need comments in configuration files, consider using JSONC (JSON with Comments), which is supported by editors like VS Code for settings files, or YAML, which allows inline comments with the hash character. Some tools strip comments from JSONC before parsing, but standard JSON parsers will reject them.