Privacy and security
Updated 11 October 2026
Your documents are personal. Here is, in plain words, what Cachety does and doesn't do, and how to check it yourself.
In short
- Your files are never uploaded: they are processed by your browser, on your device.
- No account, no tracking cookies, no visitor analytics, no ad networks.
- Nothing is kept: close the tab and your documents are gone from memory.
- The code is public and anyone can check it.
What happens when you drop a file
Your browser reads the file in your device's memory. Each page is turned into an image, the watermark is drawn on it, and a brand-new file is created. When you click Download, it is saved straight to your device.
At no point do the file, the watermark text, the recipients' names or the password travel over the internet.
What we don't collect
- Your documents and their previews.
- Your watermark text and the names of your recipients.
- Your passwords.
- Your identity: there is no account and no form.
- Your habits: no Google Analytics, no advertising pixel, no tracking cookie.
What is kept on your device
Only your settings: language, watermark appearance, auto preview and the maximum file size you chose. They stay in your browser so you don't have to set them again. No file, text or password is ever stored there. You can erase them at any time by clearing this site's data in your browser.
To work offline, your browser also keeps a copy of the site's pages (not of your documents).
Hosting and funding
The site's pages are delivered by Cloudflare. Like any web host, it technically sees visitors' IP addresses and the pages they request, in order to serve them. It never sees your documents, because they are never sent.
Donations go through GitHub Sponsors, on GitHub's own website and under its own privacy policy. Cachety never sees your payment details, and its pages contain no payment form or payment script.
There are no ads on Cachety today. To keep the project going, a few sponsored links may appear in the future, chosen by hand and true to its spirit: encryption tools, open-source software, secure document sharing. They will be clearly marked, served by Cachety itself with no ad network or third-party script, and will never depend on your documents. The page's security policy will still forbid any connection to another website.
How to check it yourself
- The airplane-mode test: open the site, switch off the internet, then watermark a document. Everything works.
- The source code is public: anyone can read it, and automated tests check on every change that no data can leave.
- For the curious: the page's security policy (CSP) forbids the browser from connecting to any other website.
- Prefer to trust no one? You can run the site on your own computer or server.
Careful protection of your copies
- Masked areas are really removed from the file, not just covered by a rectangle.
- Hidden text, metadata and the GPS location of photos are removed.
- Passwords use AES-256 encryption; once copied, a password is wiped from the clipboard after one minute.
- Found a security issue? Report it privately through the security page of the GitHub repository.
What a watermark can't do
A watermark discourages reuse of a copy and helps you trace where a leak came from. It doesn't make a copy impossible to photograph or retouch. Only send the documents you are actually asked for, and hide anything that isn't needed.