How it works
How to use the JSON5 Formatter
Paste JSON5
Paste code, drop a file onto the editor, or load the sample.
Choose a style
Pick indentation and line width (and quotes/semicolons for JavaScript-like languages).
Copy the result
Syntax errors are highlighted with their line and column so you can fix them quickly.
About this JSON5 formatter
This tool uses the reference JSON5 parser. Accepts comments, trailing commas, unquoted keys, single quotes, hex numbers and more — and can output JSON5 or strict JSON.
Formatting only changes whitespace and layout, never behaviour. Everything runs in your browser.
Built for developers
Why developers use it
Private by design
Runs 100% in your browser. Nothing you paste is uploaded, logged or stored on a server.
Instant results
Output updates as you type, with precise error locations when something is wrong.
Works offline
Once loaded, the tool keeps working without a connection. Install it as an app if you like.
Free, no sign-up
No accounts, no limits, no watermarks.
FAQ
Frequently asked questions
Does formatting change how my JSON5 works?
No. Only whitespace, line breaks and similar layout details change.
Why does it report a syntax error?
The formatter parses your code first. Invalid JSON5 is reported with the exact line and column.
Is my data uploaded anywhere?
No. Everything runs locally in your browser — nothing you paste or open is sent to a server, logged or stored. The tool keeps working offline once the page has loaded.
Keep going
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