Kobra PDF

How your files stay on your device

Every Kobra PDF tool processes your PDF inside your browser tab. The file is read from your device, transformed in memory, and saved back to your device. It is never sent to a server, including ours.

What happens when you use a tool

  1. Your browser loads the page and the code for that tool. Kobra PDF is a static website: there is no application server that could receive files.
  2. When you pick a file, the browser reads it into the memory of the tab with the standard File API. Picking a file is not an upload.
  3. Open source libraries do the work locally: pdf-lib edits PDFs, PDF.js renders pages, qpdf (compiled to WebAssembly) handles encryption and optimization, and Tesseract.js recognizes text. See the About page for details.
  4. The result is created in memory and handed to your browser as a download. Closing the tab discards everything.

What does go over the network

  • The website itself and the code of each tool, downloaded from kobrapdf.com.
  • For OCR PDF only: the Tesseract engine and the language model, a few megabytes downloaded once from the jsDelivr content network.
  • Cookie-free analytics from a self-hosted Plausible instance: the page you visited and the name of the tool you used. Never the file, its name, or its contents.

Verify it yourself

You do not have to take our word for it. In Chrome, Edge, or Firefox on a computer:

  1. Open any tool, for example Merge PDF.
  2. Press F12 (or Cmd+Option+I on a Mac) and switch to the Network tab.
  3. Clear the list, then select your files and run the tool.
  4. Look at the requests: you will see no request whose size matches your file, and no request carrying its contents. On the first run you may see the tool's code being downloaded, which flows to your browser, not from it.

What this means for you

Because files never reach us, we cannot read, keep, leak, or hand them over, even if asked. That makes Kobra PDF a good fit for contracts, financial records, IDs, and other documents you would rather not upload. The flip side is that processing uses your device: very large files depend on how much memory your browser has. Read the privacy policy for the full details.