Microsoft Office 2013 | Portable

Not strictly portable, but you can enable offline mode in Chrome and copy the Chrome user profile to a USB drive. Then, on any PC with Chrome, you can edit Google Docs without internet.

While the idea of a portable Office 2013 is attractive for convenience, unofficial portable builds carry significant legal, compatibility, and security drawbacks. Safer, supported alternatives (web apps, subscription Office, or open-source portable suites) deliver most of the same benefits without the risks. microsoft office 2013 portable

Runs any software, not just Office. Cons: Requires rebooting the host computer; slow; complex. Not strictly portable, but you can enable offline

A subscription-based service that allows you to install Office on multiple devices. LibreOffice Portable: Not strictly portable