If your needs are simple (reading PDFs, filling forms), Sumatra PDF is a legendary open-source application. It is tiny, lightning-fast, and runs as a true portable app. It doesn't have the editing power of Acrobat Pro, but it is safe and free.

Edit, sign, and convert PDFs on the go from your smartphone or tablet [5, 17, 25].

While not "portable" in the USB sense, your subscription allows for seamless use across desktop, mobile (iOS/Android), and web browsers [5, 25]. Pros & Cons Pros:

The inclusion of "2025" in the filename is a marketing tactic used by software pirates. It makes the file look current and implies it has the latest features. In reality, these files are often older versions of Acrobat Pro (re-skinned or mislabeled) or pre-release beta versions that are highly unstable.

With a standard subscription, you can install Acrobat on multiple machines (usually two). You simply deactivate one instance and activate another if you move between computers frequently.

Foxit is a long-time competitor to Adobe. They offer a portable version of their reader and editor (specifically the Enterprise or Business packs) which is safe to use and feature-rich.