OnCloudPDF

Are online PDF tools safe? Where your file goes and how to check

An online PDF tool is private only if it processes your file in your browser or deletes it quickly from its servers; many popular sites upload the file to their servers first. You can check this yourself in about two minutes with your browser's Network tab: if a large request carrying your file leaves the page, the file was uploaded.

Updated · Runs in your browser, no upload, no account

Two ways an online PDF tool can work

  • Server-based: you upload the PDF, the provider's server converts it, and you download the result. The file exists on someone else's computer for some time. Retention periods are set in each provider's policy.
  • Browser-based: your browser downloads the program once and does the work on your device. The PDF stays in your browser's memory and is not sent anywhere. OnCloudPDF works this way.

How to check it yourself in two minutes

  1. Open the PDF tool page in Chrome, Edge or Firefox and press F12 to open developer tools.
  2. Open the Network tab and click the clear button so the list is empty.
  3. Select your PDF and run the tool.
  4. Look at the requests that appear while it works. An upload shows as a POST or PUT request with a size similar to your file (sort by Size or look at the Request payload).
  5. If you see only small requests for scripts, fonts or analytics, the file did not leave your device.

Tip: test with a harmless PDF first.

What OnCloudPDF loads (and what it does not send)

OnCloudPDF does not send your PDF to its own server. Some operations still fetch program code from public content delivery networks:

  • The PDF.js worker script (used to render pages, for example in Merge, Split, PDF to Image or OCR) is loaded from the unpkg.com CDN.
  • The OCR tool also loads the Tesseract worker, core and language data from the jsDelivr CDN the first time you use it.
  • Analytics and advertising scripts (Google Analytics and Google AdSense) are loaded only after you accept cookies in the consent banner. Your file contents are never part of those requests.

These requests download code or data to your browser. They do not contain your document.

What browser-based does not guarantee

  • It does not encrypt your file or protect it if your device has malware.
  • It does not hide that you visited the site.
  • It cannot make a weak tool better: for example the OnCloudPDF Unlock tool does not break passwords, and the PDF/A tool does not produce a validated PDF/A file.

A short checklist before using any PDF website

  • Does the privacy policy say where processing happens and how long files are kept?
  • Does the Network tab show your file being uploaded?
  • Is an account required, and what happens to your files in it?
  • For passports, contracts or medical files, would an offline desktop app be safer for you?

See the tools overview for the exact limits of each OnCloudPDF tool, or compare approaches.

Frequently asked questions

Does OnCloudPDF upload my PDF?

No. Tools run in your browser and your document is not sent to OnCloudPDF servers. Program code such as the PDF.js worker is downloaded from public CDNs, which you can confirm in the Network tab.

Do online PDF converters keep my files?

Server-based converters keep files for a period defined by their own policy; it varies by provider and plan. Read the privacy policy of the specific provider.

Can I use OnCloudPDF offline?

Not fully. The page and its scripts must load from the internet first, and the PDF.js worker and OCR language data are fetched from CDNs when needed.