Using a single master password and various nicknames, one can create an infinite number of unique account passwords. These unique account passwords are commonly called password hashes, domain-specific passwords, or per-site passwords. The HowItWorks page explains what Oplop is for in more detail. A general overview of the documentation can be found in the TableOfContents.

The Oplop project aims to provide multiple implementations of its core algorithm so that one's account passwords are available at any time. The current implementations range from a website to support for various mobile phones. See Implementations for a complete list of supported technology.