JSON, YAML, XML & SQL Formatter
Format, minify, and validate JSON, YAML, XML, or SQL — instantly, entirely in your browser, with nothing uploaded.
Code & Data Formatter
Format, validate, and minify JSON, YAML, XML, or SQL
Master Your Data Payloads
Don't trust 3rd party servers with your sensitive API keys or database tokens. Our toolkit executes the parsing AST entirely within your local browser DOM.
Instant Prettify
Drop an unreadable wall of stringified JSON into the editor and instantly explode it into a beautifully formatted, color-coded structure graph.
Strict Validation
Pinpoint the exact line and character causing your application to crash. The engine detects trailing commas, missing quotes, and invalid nulls immediately.
Production Minification
When it's time to ship, use the minify toggle to violently rip out all whitespace and line-returns to keep your final network payload size absolutely minimal.
Designed For Debugging
REST API Parsing
If your Postman or cURL response is an overwhelming chunk of raw text, pasting it here allows you to cleanly read nested node arrays to find the variable you want.
Configuration Files
Validate massive `package.json` or structural mapping documents to ensure humans didn't break the syntax with a stray quote mark during manual editing.
{
"status": 200,
"response": {
"user": "admin"
}
}
What Is JSON, and Why Does Formatting Matter?
JSON (JavaScript Object Notation) is the standard format for exchanging data between servers, APIs, mobile apps, and web applications. It's built from just two structures — key-value objects and ordered arrays — which makes it easy for both humans and machines to read, but only when it's formatted properly.
Most JSON you'll actually encounter isn't formatted at all — API responses and config files are usually one unbroken line, because whitespace adds size without adding meaning for a machine. A formatter re-adds the indentation a human needs to follow the structure, without changing the data.
// Same data, minified:
{"status":200,"user":"admin","roles":["editor","viewer"]}
// After formatting:
{
"status": 200,
"user": "admin",
"roles": ["editor", "viewer"]
}
Common JSON Errors (and What They Mean)
Most "invalid JSON" errors come down to a handful of repeat offenders. Here's what the validator is actually catching when it flags your input:
Trailing commas
A comma left after the last item in an array or object — e.g. `[1, 2, 3,]`. Valid in JavaScript object literals, invalid in strict JSON.
Single quotes instead of double quotes
JSON requires double quotes for both keys and string values. `{'key': 'value'}` will fail; it must be `{"key": "value"}`.
Unquoted object keys
JavaScript lets you write `{key: "value"}`, but JSON requires every key to be a quoted string: `{"key": "value"}`.
Missing or extra commas
A comma missing between two properties, or an extra one before a closing brace, is the single most common copy-paste error.
Unescaped characters in strings
A raw newline, tab, or unescaped backslash inside a string value will break parsing — these need to be escaped as `\n`, `\t`, `\\`.
JavaScript-only values
`undefined`, `NaN`, and function values are valid in JavaScript objects but have no equivalent in JSON — they must be represented as `null` or a string.
Best Practices When Working With JSON
Validate JSON before it ships to a production API — a malformed payload fails silently in a lot of client libraries.
Use formatted, indented JSON while debugging; switch to minified JSON for the actual network payload to save bytes.
Keep nesting shallow where you can — JSON more than 4-5 levels deep is hard for the next person (including future you) to read.
Avoid pasting real API keys, tokens, or customer data into any online formatter, including this one — treat third-party tools as public by default.
Also Formats YAML, XML & SQL
Switch formats using the buttons above the editor — same tool, same privacy guarantee, no page reload.
YAML
Unlike JSON, YAML uses indentation to define structure — mixing tabs and spaces, or getting indentation levels wrong, is the single most common YAML error.
XML
Every opening tag needs a matching closing tag, and XML is case-sensitive — <Data> and <data> are different tags. The validator will flag unclosed or mismatched tags directly.
SQL
Formatting a dense one-line query into properly indented clauses (SELECT, FROM, WHERE, JOIN) makes it dramatically easier to spot logic errors before running it.
Frequently Asked Questions
What does JSON actually stand for?
JavaScript Object Notation. Despite the name, it's language-agnostic — nearly every programming language has a built-in or library-based JSON parser, which is why it became the default format for REST APIs.
Does this tool store or upload my JSON anywhere?
No. Parsing and formatting both happen in your browser via JSON.parse() and JSON.stringify() — the text never leaves your device or touches a server. Refreshing or closing the tab clears it completely.
What's the difference between formatting and minifying?
Formatting adds indentation and line breaks so a human can read the structure. Minifying strips all of that whitespace back out to produce the smallest possible payload — the data is identical either way, only the presentation changes.
Why do I get an "Unexpected token" error?
This means the parser hit a character it didn't expect at that position — almost always a stray comma, a missing quote, or a single quote used where a double quote is required. The error message includes the position, which is the fastest way to locate the problem.
Can I format very large JSON files in the browser?
Yes, up to the limits of your device's memory — there's no server-side size cap since nothing is uploaded. Multi-megabyte files will format fine on a modern laptop or desktop; very large files on low-memory mobile devices may be slower.
Is this tool really free, and are there usage limits?
Yes — it's free with no rate limits, sign-up, or watermarking, because the processing cost runs on your device rather than our servers.
Does this tool also format YAML, XML, and SQL?
Yes — use the format buttons above the editor to switch between JSON, YAML, XML, and SQL. All four run through the same browser-based formatter with no page reload.
Can I convert between JSON and YAML?
Not directly in this tool yet — switching formats resets the editor rather than converting your existing input. Format each independently for now.
Which SQL dialect does the formatter use?
Standard SQL formatting rules, which work well for most common queries. Highly dialect-specific syntax (certain PL/SQL or T-SQL extensions) may format less precisely.
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About This Utility
This tool is provided completely free of charge by Mavertex. Built by Kumar (an independent UI developer), our platform ensures your privacy by executing all operations strictly within your local browser DOM.
We prioritize zero-trust architecture. No files or inputs are ever uploaded to remote servers. This page serves as both an interactive web application and an educational resource explaining the mechanics of client-side operations. For further details on transparency and third-party network usage (including AdSense), please review our Privacy Policy.