Why your files are safe

None of the tools on justusing upload your files, because there is no server that processes them at all. This page explains how that works, and how you can check it yourself instead of taking our word for it.

How is this different from typical online tools?

Many online PDF and image tools take your file, process it on the company's server, and send the result back. Here, your own browser does the work.

How does it work without a server?

Modern browsers can run programs on their own. When you open a tool page, the program that reads and edits PDFs is downloaded from this site into your browser, and it processes your file in your device's memory. The result is also created inside the browser and saved straight to your downloads.

• Tool programs, Korean fonts, and text recognition (OCR) data all come from this site. Nothing is loaded from other companies' servers.
• Large downloads such as fonts and OCR data show their size before downloading, and are used only after checking that their content has not been changed.
• Heavy work runs in a separate background thread (Web Worker), so the page does not freeze while it is processing.

Is it safe even with ads?

Ads pay for running the site. Ad scripts can read text on the same page, so the tool area is kept apart from the page.

• The tool area, where you choose, preview, process, and download files, runs in an isolated space locked by the browser (a sandboxed iframe). Ads and visitor statistics scripts cannot look inside.
• Inside that space, browser security rules (CSP) block connections to any address other than this site. And this site has no server program that receives or stores files; it only serves files prepared in advance.
• File names and contents are never put in addresses, page titles, or visitor statistics.

How to check it yourself

You don't have to take our word for it. Your computer's browser developer tools show every address the page talks to.

1. Open a tool page (for example, Merge PDF) in Chrome or Edge. Press F12 on Windows or Cmd + Option + I on Mac to open the developer tools.
2. Choose the Network tab at the top. Every request from now on is listed there.
3. Clear the list with the clear button (a circle with a slash), then add a file to the tool, process it, and download the result.
4. Click each new request to see its address. The tool's requests only download tool programs fromjustus.ing, and none of them send out anything the size of your file.

You may also see ad or statistics addresses. Those are called by the page outside the tool and cannot reach your files. In Safari, turn on the developer features in Settings → Advanced to get the same view.

The code is public

The source code of this site is public on GitHub, so anyone can read it. Every time the site changes, automated tests run the tools in a real browser, and arequest check confirms that no request, including those to this site, carried a test file's name or content in its address or body, and that the tool area made no requests other than downloading files from this site. Changes that fail this check do not reach the site.

What we cannot promise

To be honest, there are cases this site cannot prevent.

• Browser extensions can read any page, depending on their permissions. When handling sensitive documents, keep only extensions you trust turned on.
• Processing uses your device's memory and power. Very large files may take a long time, or may not work on older phones.
• Tool programs are downloaded from this site as you use them, so you need an internet connection while processing. What is downloaded is the program, not your file.
• Downloaded results are saved on your device, so keeping them safe from then on depends on your device's security.