Yes, you can open a PDF without designated PDF reading or editing software downloaded onto your device. In fact, not having a PDF reader downloaded may be one of the reasons why your PDFs are automatically opening in Chrome. Chrome has a built-in PDF viewer that will allow you to view your PDFs. If you want to perform other functions on your PDFs (like securing them, converting them, and editing them) without downloading software, you can use Acrobat online services.