JSON Tools
JSON utilities, each on its own page, each running entirely in your browser.
JSON Formatter
Beautify minified JSON with your choice of 2-space, 4-space, or tab indentation, and copy or download the result.
Open tool →JSON Validator
Check JSON syntax and get the parser’s exact error message and position when it fails.
Open tool →JSON Tree Viewer
Explore nested JSON as a colour-coded tree, so deep structures stay readable without counting brackets.
Open tool →JSON Minifier
Strip every unnecessary byte of whitespace and see exactly how much smaller the payload becomes.
Open tool →Mock Data Generator
Generate realistic dummy data in JSON, CSV, or SQL formats with custom schemas, timestamps, and relational IDs.
Open tool →Rewriting and Inspecting
The formatter and the minifier are exact inverses: one adds whitespace between tokens, the other strips it, and running a document through both returns you to where you started. The validator and the tree viewer change nothing at all — they parse your input and report on it.
All four share the browser's native JSON.parse, so if one accepts your document the others will too, and the error you see from the validator is the exact error your own code will hit.
Frequently asked questions
Is my JSON uploaded to a server?
No. Parsing, formatting, and rendering all happen in your browser with the native JSON parser. Nothing is transmitted or stored, which makes these safe for production payloads and anything containing customer data.
What are the most common causes of invalid JSON?
Four habits borrowed from JavaScript: a trailing comma after the last element, single quotes instead of double quotes, unquoted keys, and comments. All four are valid JavaScript and none is valid JSON.
Does formatting or minifying change my data?
No. Both parse the input and re-serialise it, so keys, values, and nesting survive intact — only whitespace differs, and the two operations are exact inverses of each other.
Can these tools handle JSON with comments?
No. Comments are not part of the JSON specification and the parser rejects them. Dialects such as JSONC and JSON5 permit comments but require a parser that supports them.