JSON Formatter & Validator

What this JSON formatter does

Paste raw JSON and get it back cleanly indented, or minified down to a single line. It also validates as it goes: if the JSON is malformed, you get the specific parser error and the line and column where it broke, instead of a vague "invalid" message. Everything runs in your browser using the built-in JSON engine, so even large payloads never leave your device.

Format, minify, or sort keys

Format re-indents with two or four spaces, or tabs — whichever your codebase uses. Minify strips every optional space and newline, which is what you want before embedding JSON in a URL, a config value, or a size-sensitive payload. Sort keys reorders object keys alphabetically at every level, which makes two JSON blobs diff cleanly even if they were generated in a different order.

Why do it locally?

A lot of "JSON formatter" sites paste your data into a text box that posts to a server. That is usually harmless, but JSON often carries exactly the things you don't want to send anywhere: API keys, tokens, customer records, internal identifiers. Doing it locally removes that risk entirely — there is no server to receive the data, which you can confirm in your browser's network tab.

Large files won't freeze the tab

Formatting a multi-megabyte payload on the main thread can lock a browser tab for seconds. Past a size threshold this tool hands the work to a background Web Worker, so the page stays responsive while it runs.