JSON Formatter / Validator

Paste your JSON to validate, format, or minify it. If there's an error, its line and column are shown.

Runs 100% in your browser — your data is never sent to a server.

What Is a JSON Formatter Useful For?

JSON (JavaScript Object Notation) is a lightweight, human-readable text format used by web APIs, configuration files, and many modern databases to exchange data. It supports objects (<code>{}</code>), arrays (<code>[]</code>), strings, numbers, booleans, and <code>null</code>; since it carries far less markup than XML, it's lighter to read and parse. This tool validates the JSON you paste using the browser's own parser; if the syntax is valid, it makes it indented/readable (formats it), or strips all unnecessary whitespace down to a single line (minifies it).

The most common syntax errors are: an extra trailing comma after the last element, needing double quotes instead of single quotes, key names written without quotes, unclosed parentheses/brackets, and a forgotten closing curly brace in a nested object. When the tool detects invalid JSON, it shows exactly which line and column the error is on — so you don't have to search character by character through a long, deeply nested structure.

When to use it: while reading/debugging an API response, while editing a configuration file like package.json/tsconfig.json, or while reviewing a JSON file to check that keys are in the right order/spelling. Formatting adds indentation for a developer to read comfortably; minifying shrinks the file size to save bandwidth — API responses going to production are usually sent minified. The alphabetical key-sort option makes it easier to spot differences when comparing (diffing) two JSON files; you can copy the result straight to your clipboard or download it as a .json file.

Your JSON content — whether it's an API key, user data, or business data — is never sent to a server; all validation and conversion happens in your browser with JavaScript. That means you can safely use it to inspect a sensitive or not-yet-published API response, a real customer's production data, or an internal configuration file — since nothing is transmitted to a server, it's compatible with corporate data policies too.

Try This Next

Finished here? These might be your next step.

JSON ↔ YAMLTwo-way conversion between JSON and YAML.JWT DecodeDecode a JWT's header/payload into readable JSON.JSON → ExcelConvert your JSON data into an .xlsx or CSV file.

Frequently Asked Questions

Just paste your text and click "Format". If the JSON is valid you'll see a green confirmation with size info; if it's invalid, the error type, line, and column are shown in a red box.

It removes all unnecessary whitespace and line breaks, collapsing the JSON to a single line. Useful for API requests, config fields, and anywhere bandwidth matters.

When "Sort keys alphabetically" is checked, all keys in objects are reordered from A to Z (arrays and values are untouched). This is handy when comparing two versions of the same data (a diff), or when producing documentation/examples that expect a consistent field order.

No — the JSON standard doesn't support comments (// or /* */), so text containing one will be flagged as "invalid JSON". If you need comments, consider an extended format like JSON5/JSONC, or a separate _comment field.

Formatting adds indentation/whitespace without changing the data, making it readable for humans — useful while developing and debugging. Minifying strips all unnecessary characters to shrink the file size — preferred for API responses going to production, or config written to limited storage.

JSON files of a few megabytes are processed instantly in a modern browser. With very large files (tens of megabytes), your browser tab's memory may be strained; in that case, splitting the file into smaller chunks and processing them separately will be faster.

Last updated: