JSON Formatter online
The JSON Formatter turns raw or minified JSON into an indented, readable version (or compresses it into a single line) and shows the line and column of any error in invalid JSON. Runs entirely in your browser.
Built by Jakub Martyniak
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Input
Result
Paste JSON on the left to see a preview.
Example result
What the JSON Formatter does with your JSON
You paste raw or minified JSON, and the tool formats it with indentation for readability or converts it back into a compact single line. If the JSON is invalid, it shows the error with its line and column. The values below are a fixed example; your output depends on your input.
Example · Format with 2 spaces
Input (minified)
{"name":"Alice","age":30,"active":true}Output (formatted)
{ "name": "Alice", "age": 30, "active": true}Error case: {"name": "Alice",}
- 1 error
Error · Line 1, column 18JSON expects another entry after the comma, but there is a closing bracket here.
The tool highlights the same spot and shows your browser's exact error message. Without the extra comma, the JSON is valid.
Why this tool
More than a simple text field
Everything you need for clean JSON.
Format & Minify
Switch between readable, indented JSON and maximally compact minified output with one click.
Runs only in the browser
Validation with JSON.parse() and formatting run directly in your browser—nothing is uploaded or logged.
Syntax Highlighting
Color highlighting of keys, values, and types for quickly scanning long structures, for results up to 150,000 characters.
Line and column for errors
For invalid JSON, the error message shows the line and column where possible.
Custom indentation
2 spaces, 4 spaces, or a tab—switch directly in formatting mode.
No artificial limit
No artificial file size limit—only your browser's performance limits.
How it works
How the formatter works
Three steps to clean JSON.
Step 1
Paste JSON
Paste your JSON or upload a file — everything runs directly in your browser.
Step 2
Choose Format or Minify
Choose Format for readability or Minify for the smallest possible file size.
Step 3
Copy or download
Copy the result to your clipboard or download it as a .json file.
About the tool
What does this JSON formatter do?
This JSON formatter formats, validates, and minifies JSON for free without registration—entirely client-side in your browser. Validation uses JSON.parse(), and formatting changes only whitespace: numbers, escapes, and duplicate keys remain exactly as entered. Choose from 3 indentation options (2 spaces, 4 spaces, or a tab), with no artificial file size limit.
Formatting adds indentation and line breaks so you can quickly read even deeply nested JSON. Minifying removes all unnecessary whitespace for the smallest possible file size, such as for production use in an API. Validation happens automatically: if your JSON is invalid, the tool shows a clear error message, including the line and column where possible, instead of empty output.
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FAQ
Frequently asked questions
Brief answers about JSON, privacy, and this tool.
The formatter turns the single line {"name":"Alice","age":30,"active":true} into 5 readable lines with 2-space indentation and one key-value pair per line. Minifying turns it back into {"name":"Alice","age":30,"active":true}. If your JSON is invalid, you get an error message with the line and column instead of output.
A JSON Formatter is a tool that turns raw or minified JSON into a readable, indented format while checking whether the data is valid JSON. This tool does exactly that, right in your browser.
Yes, completely free, with no sign-up and no limits beyond your browser's capabilities.
No. Validation (with JSON.parse()), formatting, and minification run entirely in your browser—no uploads or logging. Your values remain exactly as entered. This matters because pasted JSON often contains real API responses or configuration data with sensitive values.
Formatting adds indentation and line breaks for readability. Minifying removes unnecessary whitespace for the smallest possible file size, such as for production use in an API. Both produce identical JSON content.
The tool displays a clear error message—with line and column where possible—instead of blank output, so you can quickly find the error in your text.
2 spaces, 4 spaces, or a tab, switchable directly in formatting mode.
No artificial limit—only your browser's performance limits. Very large files (several MB) may display more slowly. A result over 150,000 characters is shown as plain text without syntax highlighting.
A simple example is {"name": "Alice", "age": 30, "active": true}—an object of key-value pairs containing strings, numbers, and booleans. You can paste JSON like this above to see it formatted or minified.
Upload the file using “Choose file” or paste its contents directly. The tool displays it formatted immediately, with syntax highlighting up to 150,000 characters, without any additional software.
Type or paste your JSON into the input field, then download the result as a .json file. No additional software is needed to create a new file.
Upload your file using “Choose file,” edit its contents directly in the input field, and download the updated result as a .json file.
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