Format, validate and query JSON in one place.
A fast, private JSON toolkit — prettify and minify, catch syntax errors, explore a collapsible tree, diff two documents and run JSONPath queries. Everything runs in your browser; your data never leaves the page.
Why JsonCraft
Smart formatter
Turn minified JSON into a clean, indented document with syntax highlighting and a collapsible tree — or minify it back in one click.
Instant validator
Catch syntax errors as you type. The status bar reports the exact message and position so you can fix invalid JSON in seconds.
JSONPath & diff
Query data with full JSONPath — keys, indexes, wildcards and recursive search — and compare two documents to see exactly what changed.
Private & offline
Everything runs in your browser. Your JSON — tokens, secrets and all — never leaves the page or touches a server.
JSON, made effortless
JsonCraft is a free online JSON toolkit for the tasks developers hit every day: formatting a minified response into something readable, validating a payload to find the one broken comma, minifying data before shipping it, comparing two versions of a document, and pulling values out of deep structures with JSONPath. Each function lives in one focused studio, so you get a clear answer without juggling a dozen separate sites.
Everything runs client-side in your browser, which makes it fast, private and available offline once loaded. There is nothing to install and no account to create. Because the JSON you paste never leaves the page, it is safe to work with access tokens, API keys and personal data. And every feature is backed by a plain-language guide that explains the format, the query syntax and the mistakes to avoid.
Guides & articles
Plain-language explainers on JSON, JSONPath and the details behind the format.
What Is JSON? A Plain-Language Introduction
JSON moves data across almost every API and config file. What it is, the six value types it supports, and the rules that keep a document valid.
JSON vs XML vs YAML: Which One and When
Three formats carry most of the world's structured data. Here's how JSON, XML and YAML differ in verbosity, features and the jobs each is best at.
Common JSON Syntax Errors and How to Fix Them
Most JSON failures come from the same few mistakes. Spot trailing commas, wrong quotes and unescaped characters — and learn to read the parser's message.
Frequently asked questions
Is my data sent to a server?+
No. JsonCraft is a fully client-side application. Every operation — formatting, validation, diff and JSONPath — runs in your browser's JavaScript engine, and nothing is transmitted to a remote server. You can safely paste JSON containing access tokens, personal data or secret keys; when you close the tab, nothing remains except the clipboard if you clicked Copy.
What is JSON and how does it differ from XML?+
JSON (JavaScript Object Notation) is a text-based data format built on JavaScript syntax. It describes data with objects (curly braces), arrays (square brackets) and primitives (strings, numbers, booleans, null). It is roughly 20–40% more compact than XML for the same data and is natively supported in JavaScript through JSON.parse() and JSON.stringify(), which is why it has become the de facto standard for REST APIs and configuration files.
How does JsonCraft detect syntax errors?+
JsonCraft validates with the browser's native JSON.parse(), the most reliable way to check JSON. Validation runs in real time, shortly after you stop typing. When something is wrong, the status banner turns red and shows the standard SyntaxError message and position — for example "Unexpected token ' in JSON at position 8" means a single quote was used instead of a double quote at character 8.
What is JSONPath and how do I use it?+
JSONPath is a query language for extracting values from JSON, analogous to XPath for XML. A query starts with $ (the document root) and then describes a path: .key for a property, [n] for an array index, [*] or .* for a wildcard, and .. for a recursive search at any depth. Open the JSONPath tab, paste your JSON, type an expression like $.store.books[*].title and run it to see the matches.
Does JsonCraft support JSON5 and comments?+
JsonCraft works with standard JSON per RFC 8259, which does not allow comments (// or /* */), single quotes, trailing commas, non-numeric values like NaN or Infinity, or unquoted keys. JSON5 is an extension that adds those features; if your config file uses JSON5, convert it to standard JSON first and then format or query it here.
How do I compare two JSON objects?+
Open the Diff tab, paste the first document (for example an old API response) into the left field and the second into the right, then run the comparison. JsonCraft lists every change with its full path — green (+) for added keys, red (−) for removed and yellow (~) for changed values — along with a summary count at the top so you can see the scope of the difference at a glance.