Formateador y Validador JSON

What the JSON Formatter & Validator does

JSON — JavaScript Object Notation, standardised as RFC 8259 — is the lingua franca of web APIs, configuration files and data interchange. This tool does three related jobs on any JSON you paste in. It pretty-prints (formats) it with clean, consistent indentation so a wall of text becomes a readable tree; it minifies it by stripping every unnecessary space and line break to shrink a payload; and it validates it, telling you immediately whether the document is well-formed and, if not, where the parser gave up. You reach for it constantly: reading a minified API response, tidying a config file, spotting the stray comma that a service is rejecting, or squeezing a body down before sending it.

JSON is deceptively strict. Its entire type system is small — objects (key/value maps), arrays (ordered lists), strings, numbers, the literals true, false and null — and its syntax rules are unforgiving. Keys and strings must use double quotes, never single quotes; there are no comments; and no trailing comma is allowed after the last element of an object or array. Those three rules cause the overwhelming majority of "invalid JSON" errors.

How formatting, minifying and validation work

Under the hood the tool parses your text with the browser's native, standards-compliant JSON parser, which is the same engine your applications use, so what passes here passes there. Once parsed into an in-memory structure, formatting re-serialises it with your chosen indentation — two spaces, four spaces, or a tab — nesting each level one step deeper so the shape of the data is obvious at a glance. Minifying re-serialises the same structure with no indentation and no insignificant whitespace, producing the most compact valid representation, which is what you want for storage or transport. Validation simply attempts the parse and reports the outcome: a success, or the parser's error message describing what it expected and roughly where it stopped.

Because it uses a real parser rather than a loose text pass, the validator catches subtle problems that eyeballing misses: an unquoted key, a value quoted with apostrophes, a missing closing brace, a control character inside a string, or that infamous trailing comma. When you are debugging an integration and are not sure whether the fault is your JSON or the server's, formatting the response is the fastest way to see its true structure — and our API documentation shows the exact JSON shapes our endpoints expect and return, so you can compare side by side.

Examples, use cases and gotchas

Paste a compact response such as {"user":{"id":7,"tags":["a","b"],"active":true}} and formatting expands it into an indented tree you can actually read; minifying does the reverse. A config file that a service keeps rejecting will often reveal, once formatted, a single misplaced comma or a comment that slipped in from a JavaScript habit. Everyday uses include inspecting webhook payloads, diffing two API responses after pretty-printing both, and preparing a minimal request body.

• JSON is not a JavaScript object literal: no comments, no trailing commas, and every key must be a double-quoted string.
• Numbers are IEEE-754 doubles, so very large integers (past 2^53) can silently lose precision — send them as strings if exactness matters.
• Formatting preserves the key order as written; JSON itself defines objects as unordered, so do not rely on order for correctness.
• A leading byte-order mark or a wrapping pair of quotes from a copy-paste is a common cause of a "unexpected token" error.

Your privacy

All parsing, formatting, minifying and validation happen one hundred percent locally in your browser. Your JSON — which may be an API response full of personal fields, an access token, or a private configuration — never leaves your device, is never sent to any server, and is never logged. Nothing is uploaded and nothing is retained after you close the tab. For data that frequently carries credentials and customer records, doing the work on-device is the only responsible design, and that is exactly how this validator is built.