How your data stays local

JSON Mill does its work in your browser. Formatting, validating and converting happen on your device, in a background thread of the page you are looking at.

What never leaves your device

Anything you paste, type, open or drop into the workspace stays in this browser tab. JSON Mill has no server endpoint that receives your JSON while you are only viewing, editing or converting it.

What is sent, and when

Data leaves your device only when you ask it to:

• Save sends the document to your JSON Mill account so you can open it later. Saved documents are private to you.
• Share creates a link only after you choose "Anyone with the link". Links expire, you can stop sharing at any time, and shared documents are never listed or indexed by search engines.

Before either of these, JSON Mill tells you what will be sent and where.

Check it yourself

Open your browser's developer tools, choose the Network tab, and use the workspace. You will see the page load its own scripts and stylesheets, and nothing else, until you save or share.

The site also sends a strict Content Security Policy that only allows connections back to JSON Mill itself, so a third-party script cannot quietly send your data elsewhere.

Why we built it this way

In 2025, researchers found that two popular online JSON formatters exposed tens of thousands of saved documents, including passwords and API keys, through guessable links and a public list of recent saves. JSON Mill has no public list, no guessable links, and nothing to expose for the work you never chose to save.