Formateador, Validador y Embellecedor de JSON en Línea
Paste JSON to validate and format it as you type. Syntax errors show the parser's message so you can find the broken comma or quote; valid JSON comes back indented with 2, 4 or 8 spaces, ready to copy or download. Everything runs in your browser.
Indentación:
JSON de Entrada
Pega tus datos JSON sin formatear aquí
Characters: 0Lines: 1
JSON Formateado
Validated and formatted JSON
Characters: 0Lines: 1
What is a JSON formatter and validator?
A JSON formatter and validator is a tool that checks whether text is valid JSON and, if it is, re-indents it so people can read it. This free JSON formatter validates as you type: invalid JSON shows the parser's error message, and valid JSON comes back indented with 2, 4 or 8 spaces, ready to copy or download. It runs in your browser.
What the JSON formatter does
A JSON syntax checker and beautifier in one screen: input on the left, formatted output on the right.
Validates as you type
Every change is parsed. Valid JSON is marked valid; invalid JSON shows the parser's error message.
Formats and beautifies
Re-indents valid JSON with 2, 4 or 8 spaces so nested objects and arrays are easy to read.
Line counts
Shows how many lines the input and the formatted output have.
Copy or download
Copy the formatted JSON, or download it as a .json file.
Sample JSON
Load a sample object to see how the formatter handles nesting, arrays and types.
Parsing happens in your browser; the JSON you paste is not sent to a server.
How to format and validate JSON
Paste, read the result, fix any error, copy.
Paste your JSON
Paste minified or messy JSON into the input, or click the sample button to see how it works.
Read the validation result
The input is parsed on every change. Valid JSON is marked valid; invalid JSON shows the parser's error message.
Fix any syntax error
Look near the position the error names. The usual causes are a trailing comma, single quotes, an unquoted key or a missing bracket.
Choose the indentation
Pick 2, 4 or 8 spaces. The formatted output updates straight away.
Copy or download
Copy the formatted JSON, or download it as formatted.json.
How to read the result
The output panel shows one of two things: formatted JSON, or the reason it could not be parsed.
Valid
The text is standard JSON. The output is the same data, re-indented; keys and values are not changed or reordered.
Error message
The browser's JSON parser explains what it expected and where it stopped, often as a character position or a line and column.
Unexpected token
Usually a trailing comma, a single quote, a comment or an unquoted key just before the position named.
Unexpected end of JSON input
Something was never closed: a bracket, a brace or a string's closing quote.
Line counts
Input and output line counts help you compare a one-line payload with its formatted version.
Why format and validate JSON?
JSON is the format most APIs, webhooks, config files and structured-data blocks use. Machines send it as compact single lines, which are hard for people to read and easy to break when edited by hand. Formatting adds line breaks and indentation; validating confirms that every bracket, quote and comma is where JSON requires it.
Use it to debug an API response, check a config file before you deploy it, or make sure a JSON-LD block parses before you add it to a page.
The most common JSON syntax errors
Most invalid JSON fails for one of these reasons:
A trailing comma after the last item in an object or array.
Single quotes around keys or strings; JSON allows only double quotes.
Keys without quotes, as in JavaScript objects.
Comments (// or /* */), which standard JSON doesn't support.
Unescaped backslashes or line breaks inside a string.
A missing comma between two items, or a bracket that is never closed.
Formatting, beautifying and minifying
Beautifying (or pretty-printing) adds indentation and line breaks so people can read the data. Minifying does the opposite and removes all optional whitespace to make the payload smaller. This tool beautifies; the data is identical either way.
Validación en Tiempo Real
Validación instantánea de JSON con mensajes de error detallados y resaltado de sintaxis.
Descargar y Copiar
Descarga archivos JSON formateados o cópialos al portapapeles con un solo clic.
Formato Personalizable
Elige tu tamaño de indentación preferido (2, 4 u 8 espacios) para un formato consistente.
What this JSON formatter doesn't do
It doesn't repair invalid JSON. It tells you it is invalid and shows the parser's message; you make the fix.
It doesn't minify, sort keys or convert to other formats. Use the JSON to YAML or JSON to CSV tools for conversions.
It reads standard JSON only, not JSON5 or JSON with comments.
It has no tree view. Use the JSON viewer to explore nested data.
It checks syntax, not meaning: it won't tell you whether a JSON-LD block qualifies for rich results.
JSON5 is an extension of JSON that allows comments, trailing commas, single-quoted strings and unquoted keys. Many parsers don't accept it. This formatter validates standard JSON only, so remove JSON5-only syntax before you paste it.
What does JSON minification do?
Minification removes every optional space, tab and line break, so the JSON is as small as possible for sending over a network. The data doesn't change. This tool formats (beautifies) JSON; it doesn't minify it.
How do I find and fix JSON syntax errors?
Paste the JSON into the input. If it doesn't parse, the parser's error message appears, usually naming the position where it stopped. Look just before that point for a trailing comma, a single quote, an unquoted key or a missing bracket, fix it, and the formatted output appears as soon as the JSON is valid.
What is the difference between beautifying and formatting JSON?
They usually mean the same thing: adding indentation and line breaks so JSON is readable. This tool also validates the syntax first, so you only get formatted output for JSON that parses. You choose 2, 4 or 8 spaces of indentation.
What is JSON?
JSON (JavaScript Object Notation) is a lightweight, text-based data format for storing and transmitting structured data. It uses key-value pairs and ordered arrays, and is the dominant format for REST APIs, NoSQL databases like MongoDB, configuration files, and data interchange between web services.
What are the most common JSON syntax errors?
The five most frequent JSON errors are: trailing commas after the last item in an object or array; single-quoted strings (JSON requires double quotes); unquoted keys (all keys must be double-quoted strings); comments (standard JSON does not support //); and unescaped backslashes or control characters inside string values.
Is it safe to paste sensitive JSON data into an online formatter?
This tool processes all JSON entirely within your browser — no data is sent to any server. It is safe to paste API responses, tokens, or private configuration data for local formatting. The processing happens client-side with no network requests.
What is a JSON formatter?
A JSON formatter is a tool that takes unformatted JSON data and formats it with proper indentation and spacing to make it more readable and easier to work with.
How do I validate JSON?
To validate JSON, simply paste your JSON data into the input field. The tool will automatically check for syntax errors and display any validation issues.
Can I download formatted JSON?
Yes, you can download the formatted JSON as a .json file using the download button, or copy it to your clipboard.
Does the formatter fix invalid JSON?
No. It tells you that the JSON is invalid and shows the parser's error message, so you can correct it yourself. Once it parses, the formatted output appears straight away.
Is my JSON uploaded anywhere?
No. Validation and formatting run in your browser with the built-in JSON parser, so nothing you paste leaves your device.
More free JSON tools
View the same data as a tree, convert it, or turn it into structured data.
JSON-LD markup tells Google and AI engines what a page is. AI Rank Lab's free audit checks a page's structured data along with the rest of its SEO, AEO and GEO readiness.
SEO, AEO and GEO audit
Paste a URL. The audit checks structured data, headings and on-page signals, plus robots.txt, sitemap.xml and llms.txt, and returns three scores with fixes ordered by impact.
