Private by design
Your JSON never leaves your browser.
Every tool runs locally with JavaScript and WebAssembly. Paste API keys, customer data or production configs without a second thought.
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How it works
How to use the JSON Formatter
Add your JSON
Paste it into the input editor, drop a .json file onto it, open a file, or load it from a URL.
See it formatted live
The output updates as you type. Choose 2 or 4 spaces or tabs, and optionally sort keys alphabetically.
Fix any errors
Invalid JSON is underlined with the exact line and column, a plain-English explanation and a suggested fix. Try Auto-repair for common mistakes.
Copy, download or share
Copy the result, download it as a file, or create a private share link that stores the data only in the URL.
What is a JSON formatter?
JSON (JavaScript Object Notation) is the most common format for APIs, configuration files and data exchange. Machines often produce it minified — all on one line with no spaces — which is efficient but nearly impossible to read. A JSON formatter (also called a JSON beautifier or pretty-printer) adds consistent indentation and line breaks so the structure is obvious at a glance.
This formatter also validates your JSON against the official specification (RFC 8259) while you type, so you find syntax errors before your code or API does.
FAQ
Frequently asked questions
What is the difference between formatting and validating JSON?
Formatting changes whitespace to make JSON readable. Validating checks that the text follows the JSON grammar — double-quoted keys, no trailing commas, no comments, correctly closed brackets and so on. This tool does both at the same time.
Which indentation should I use?
Two spaces is the most common convention for JSON and keeps deeply nested data compact. Four spaces or tabs are popular in some codebases. Your choice is remembered for next time.
Can I sort JSON keys alphabetically?
Yes. Enable “Sort keys” to order every object’s keys recursively using natural ordering (so key2 comes before key10). Arrays keep their original order because their order is meaningful.
Is my JSON sent to a server?
No. Parsing, validation, formatting and the tree view all run in your browser using JavaScript and a Web Worker. Your data never leaves your device. You can even use the tool offline once the page has loaded.
How large a JSON file can I open?
Files of tens of megabytes work well on a modern laptop. Processing runs in a background thread so the page stays responsive, the editor only renders what is visible, and the tree view is virtualised. The hard limit is 200 MB per file.
Does formatting change my numbers?
Never. Many online formatters use JSON.parse, which silently rounds big integers (like 64-bit IDs) and rewrites numbers such as 1.0 or 1e3. This tool keeps every number and string escape exactly as you wrote it — only whitespace changes.
Keep going
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