What is a JSON viewer?

A JSON viewer displays structured JSON in a readable format, often with a collapsible tree, search and validation.

How do I format JSON online?

Paste your JSON into Tool Kumar. The formatter creates an indented view, while the validator reports syntax errors.

Is this JSON viewer private?

Yes. Parsing and formatting happen in your browser, so your document does not need to leave your device.

Can I validate a large JSON file?

Yes. The viewer is designed for large documents and keeps the input local while it parses the file.

Tool Kumar resources

JSON resources you can cite and reuse

Standards-based explanations and small examples for documentation, code reviews, API work and classroom notes. Start with the JSON syntax reference or download a ready-made example.

Reference

JSON syntax reference

A standards-based guide to values, objects, arrays, strings, numbers, whitespace and common JSON mistakes.

Examples

JSON examples for APIs and tests

Small, valid documents for API responses, application configuration and nested data, with downloadable files.

Guide

How to format and validate JSON

A practical walkthrough for finding syntax errors, choosing indentation and repairing loose JSON safely.

History

The origin of JSON

The story from early browser messaging to RFC 8259, ECMA-404 and the format used by APIs today.