JSON Formatter & Validator - Pretty Print, Minify, Validate

How to use this tool

1. Paste your JSON. Paste or type JSON, open a local .json file, or drop a file into the input box. The formatter accepts objects, arrays, strings, numbers, booleans, and null.
2. Choose an indent style. Select 2 spaces (default), 4 spaces, tabs, or Minified. Minified removes all unnecessary whitespace for compact output.
3. Optionally sort keys. Enable "Sort keys" to alphabetically sort all object keys at every nesting level. Useful for diffing or normalizing JSON.
4. View output and stats. Copy or download formatted JSON, or explore it in the collapsible tree. Expand or collapse all tree nodes for smaller inputs. Stats show object count, array count, key count, nesting depth, character counts, and UTF-8 sizes.

What does a JSON formatter do?

A JSON formatter takes raw, often compressed or inconsistently indented JSON text and re-serializes it with consistent indentation. The result is easier to read, diff, and debug. This formatter supports 2-space and 4-space indentation (the two most common styles in JavaScript projects), tab indentation (common in Go and other languages), and minification (useful for shrinking payloads for HTTP requests or storage).

JSON validation and error location

Validation is performed by the browser's native JSON.parse: the same parser your JavaScript runtime uses. When the input is invalid, the parser throws a SyntaxError containing a character position (in V8/Chrome/Node) or a line and column number (in Firefox/SpiderMonkey). This formatter extracts that information and displays it as a human-readable "Line X, column Y" message, making it much faster to locate the offending character in large JSON documents.

Key sorting

Enabling Sort keys reorders every object's properties alphabetically at every level of nesting. This is useful for producing deterministic JSON output, for example when comparing two API responses that contain the same data in different key orders, or when diffing configuration files. Sorting is applied before formatting, so the output is fully deterministic regardless of the original key order.

Tree view

The Tree view tab renders the parsed JSON as a collapsible tree. Each object and array can be expanded or collapsed independently. Objects show their key count and arrays show their element count in the collapsed state. This is useful for navigating deeply nested JSON without manually searching through text. The Expand all and Collapse all controls apply to the full tree; Expand all is limited to documents with at most 1,000 values so a very large payload does not flood the page with rendered nodes.

JSON5 and JSONC

Standard JSON has strict rules: no comments, no trailing commas, no single-quoted strings, no unquoted keys. Two popular supersets relax these rules:

• JSON5: supports comments, trailing commas, single-quoted strings, unquoted keys, and hex literals. Used in some configuration tools.
• JSONC (JSON with Comments): JSON plus C-style // and /* */ comments. Used by VS Code, TypeScript (tsconfig.json), and other tooling.

Strict JSON is the default. Turn on Allow JSONC comments and trailing commas to format JSONC configuration files without editing out comments first. The option removes comments and trailing commas while preserving line breaks for useful parser error locations. It does not enable the broader JSON5 syntax, so single-quoted strings, unquoted keys, and hexadecimal numbers still need conversion.

Large JSON performance

This tool handles most JSON files well. For very large files (>5 MB), browser-based tools become slow due to rendering limits. For large JSON, consider command-line tools:

• jq . input.json - format and query JSON with the ubiquitous jq tool
• python3 -m json.tool input.json - format using Python's standard library
• cat input.json | fx - interactive JSON explorer in the terminal

Local files and privacy

Use Open file or drop a .json file into the input area to read it on this device. The filename and file size are shown above the result, and Download saves the current formatted output as a new .json file. File reading, parsing, sorting, formatting, and saving all happen in the browser; the tool does not upload your JSON. The input and formatted size summary reports character counts and UTF-8 byte sizes, which helps compare the effect of minification on a payload.