JSON Formatter
Format, beautify, minify, and validate JSON with clear, line-numbered error messages.
Free online JSON formatter and validator
A JSON formatter turns compact or messy JSON into clean, readable, indented text — and tells you immediately if it is invalid. ProseTool's JSON formatter beautifies, minifies, and validates JSON entirely in your browser, with a clear error message when something is wrong. Choose your indent size and format with one click.
JSON is the language of APIs and configuration, but raw JSON is often delivered as a single unreadable line. Formatting it makes the structure obvious so you can read it, debug it, and spot mistakes. Validation catches the small syntax errors — a stray comma, a missing quote — that break parsing.
How to use the JSON formatter
- Paste your JSON into the input box.
- Pick an indent size: 2 spaces, 4 spaces, or a tab.
- Click Format to beautify and validate, or Minify to compress.
- Copy the result, or read the error message if the JSON is invalid.
Features
- Beautify JSON with clean, consistent indentation.
- Minify JSON to the smallest valid size for transfer.
- Validation with helpful, specific error messages.
- Indent control — 2 spaces, 4 spaces, or tabs.
- Completely private — your data never leaves the browser.
Benefits of formatting JSON
Readable JSON is faster to work with and far easier to debug. Developers spend less time hunting for the source of a parsing error when the structure is laid out clearly, and minified output keeps payloads small in production. Because JSON often contains private or proprietary data, processing it locally rather than on a remote server is an important security advantage.
Whether you are inspecting an API response, editing a configuration file, or preparing data for an import, a formatter that validates as it beautifies saves time and prevents errors. With no length limit and instant results, it handles everything from a tiny object to a large nested document.
Frequently asked questions
Does the JSON formatter validate my JSON?
Yes. When you format, the tool parses your input with the browser's native JSON engine. If anything is invalid, it shows the error message so you can find and fix the problem.
What is the difference between beautify and minify?
Beautify adds indentation and line breaks to make JSON readable. Minify strips all unnecessary whitespace to make the JSON as small as possible for transmission or storage. Both produce identical data.
Is my JSON sent to a server?
No. Parsing and formatting happen entirely in your browser using built-in JavaScript. Your data — which may be sensitive — never leaves your device.
Why does it say "Unexpected token"?
That error usually means a missing comma, an extra trailing comma, unquoted keys, or single quotes instead of double quotes. JSON requires double-quoted keys and strings and no trailing commas.