JSON Formatter & Validator
Format, validate, and minify JSON. Pretty-print with syntax highlighting and tree view.
About this calculator
Paste JSON, press Format to pretty-print it, Minify to compress it or Validate to check it. The output panel has a Copy button.
Developers use it to read API responses, fix config files and clean data. The check runs in your browser, so private payloads stay private.
How to use it
- Paste your JSON.
- Press Format, Minify or Validate.
- Copy the result.
Rules of JSON
JSON has six value types: object {}, array [], string, number, true/false and null. Keys and strings need double quotes, there are no trailing commas, no comments and no single quotes. The formatter parses your text; if it parses, it re-prints it with indentation (or with all whitespace removed when minifying). If not, the error shows where the problem is.
Worked example
Input {"name":"Asha","age":30,"skills":["js","sql"]}
| Formatted | Each key on its own line, indented two spaces |
| Minified | {"name":"Asha","age":30,"skills":["js","sql"]} |
Runs entirely in your browser. Nothing you paste is uploaded.
Tips and common mistakes
- Most JSON errors are trailing commas, single quotes or unquoted keys.
- Minify JSON for production payloads and format it for reading.
- Large numbers beyond 2⁵³ lose precision in JavaScript.
- JSON has no comments; use a separate field if you need notes.
- Validate API responses before parsing in code.
Frequently asked questions
What is JSON?
A text format for structured data, based on JavaScript object syntax.
Why does my JSON fail to parse?
Usually a trailing comma, single quotes or missing quote marks.
What does minify do?
Removes all unneeded whitespace.
Can JSON have comments?
No.
What is the difference between JSON and a JavaScript object?
JSON is stricter: double quotes only, no functions or undefined.
Is my data sent to a server?
No.