About FilePresto, and your privacy

FilePresto is a set of tools for everyday jobs with photos, audio and video, built on one rule: your files are processed on your device and are not uploaded to FilePresto. Our PDF tools live on TeddyPDF, a sister site from the same maker that works in exactly the same way.

How it works

When you open a tool, your browser downloads the page and the software it needs, from this website only. When you then choose a file, the work is done by that software inside your browser. Nothing about your file is sent back.

Some tools need larger pieces of software, such as the one that reads iPhone photos, the picture engine, or the text recognition engine. These are fetched from this website when you first need them, and your browser usually keeps them for next time.

The privacy lock

Most websites that promise not to keep your files are asking you to trust them. FilePresto is built so that trust is not needed.

When you choose a file, the tool first fetches every piece of software it needs. Then, before your file is opened, the page locks itself: it tells your browser to refuse any further attempt by the page to fetch, upload or send anything, to anyone, including us. Your browser enforces this, not our code, and it cannot be undone without reloading the page. The green badge at the top of each tool turns solid when the lock is on.

Once locked, the page cannot make a request of any kind: not to another website, and not to this one. Helper programs that a tool starts for heavy work, such as reading PDF pages, making an MP3 or recognising text, are created from software already in the page and are locked in the same way. Our automated tests check this on every tool: after the lock goes on, our test web server receives nothing at all.

If you are weighing FilePresto against a converter that uploads files, our guide to what online converters do with your files sets out what seven popular services say about themselves.

The one thing a lock cannot stop is you choosing to go somewhere else: clicking a link simply opens that page, and your file is not part of it.

Moving to another tool with Keep going with this file opens the next tool in a new tab and passes your file across inside your browser. The new tab gets ready and locks itself before it accepts the file.

How you can check

1. Switch off your internet. Open a tool, let it load, then disconnect. It will still work, because nothing needs to be sent anywhere.
2. Look at the network log. On a computer, open your browser's developer tools and choose the Network tab. Use a tool and watch: you will see the page's own files, and nothing sent to anyone else.
3. Test the lock. Open a file in any tool, then in the developer tools Console type fetch('/') and press Enter. The browser refuses, because the page is locked.

Each page also carries an instruction, called a content security policy, that tells your browser to refuse to load anything from, or send anything to, any other website. So even a mistake on our part could not send your file elsewhere.

What we do not do

There are no adverts, no analytics, no advertising trackers, no cookies and no accounts. The pages load no fonts or scripts from any other company.

What any website's host sees

To deliver any web page, the company that hosts a website receives the ordinary details of the request, such as your internet address and which page was asked for. That is true of every website. What it never receives from FilePresto is your file, or anything about its contents, because your file is not sent to FilePresto.

Built on open-source software

Several tools rely on excellent free software written by others. The licences page lists each one and where to find its source code.