JSON Formatter & Validator
Beautify, minify and validate JSON data with syntax highlighting and error detection.
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What Is a JSON Formatter & Validator?
JSON (JavaScript Object Notation) is a lightweight, human-readable data format widely used for APIs, configuration files, and data exchange between services. A JSON formatter takes raw, unindented or minified JSON text and restructures it with consistent indentation so developers can read and debug it effortlessly.
A JSON validator checks your data against the JSON specification — catching missing commas, unclosed brackets, duplicate keys, and other syntax errors before they cause bugs in production. This tool combines both functions: it validates your JSON in real time and instantly highlights any errors with the exact line and column where the problem occurred.
How to Use This Tool
- Paste or type your JSON data into the Input panel on the left.
- The output automatically updates. Switch between Beautify (readable, indented) and Minify (compact, no whitespace) modes.
- Choose your preferred indent size — 2 spaces, 4 spaces, or tabs.
- If your JSON is invalid, a red error message shows the exact line and column of the problem.
- When valid, statistics appear: total key count, value count, maximum nesting depth, minified size, and root type.
- Click Copy Output to copy the formatted or minified JSON to your clipboard.
- Use Load Sample to see an example JSON structure and test the tool.
Common Use Cases
- API debugging: Paste raw API responses to read nested objects clearly.
- Config file editing: Validate
package.json,tsconfig.json, or any JSON config before saving. - Data preparation: Minify JSON payloads to reduce bandwidth and request size.
- Code reviews: Share beautified JSON with teammates instead of a wall of text.
- Learning: Explore the structure, depth, and key count of unfamiliar JSON datasets.
Frequently Asked Questions
What is the difference between beautify and minify?
Beautifying (also called “pretty-printing”) adds line breaks and indentation to make JSON human-readable. Minifying removes all unnecessary whitespace to produce the smallest possible string — ideal for API payloads and storage where every byte counts.
Is my JSON data sent to a server?
No. This tool runs entirely in your browser using JavaScript. Your data never leaves your device. It’s 100% private and works offline once the page is loaded.
Why does my JSON show an error even though it looks correct?
Common issues include: trailing commas after the last item (not allowed in standard JSON), single quotes instead of double quotes around strings, unquoted keys, or JavaScript-style comments (// …) which are not part of the JSON spec. The error message will point you to the exact line and column.
What does “Max Depth” mean?
Max depth indicates how many levels of nesting exist in your JSON. A flat object like {"a":1} has a depth of 1. An object inside an object has depth 2, and so on. Deep nesting can sometimes indicate overly complex data structures.
Can I format very large JSON files?
Yes — the tool handles large JSON strings, though extremely large files (tens of megabytes) may cause the browser to slow down due to syntax highlighting processing. For very large files, consider minifying to quickly validate structure without rendering the full highlighted output.
Does this tool support JSON5 or JSONC (JSON with comments)?
This tool validates against the strict JSON standard (RFC 8259), which does not allow comments, trailing commas, or unquoted keys. If you need JSON5 or JSONC support, you would need to pre-process the input to strip those extensions before validation.