I am writing a program and it is open source on GitHub. Part of this program is a file system, and I used an open-source file system called the "Simple File System" as design inspiration. My version, however, is simpler and more custom for my application. Anyone looking at what I did who knows how Simple File System works will see the similarities, but I wrote my own code and used the SFS documentation for guidance. How do I attribute SFS?
Legally, the question is whether your work is a derivative work of SFS. If it is, then you must do more than attribute SFS: you must follow whatever the license conditions are for the use of SFS - for example, if it is GPL-licensed then your code must also be GPL-licensed. If your code is not a derivative work, then there is no legal requirement.
Ethically, it's largely up to you. There are no particular standards around this, but it is of course considered polite to acknowledge influences on your design even if they don't reach the level of a derivative work.