Which font in the Google font library looks most like Optima?

What gives Optima its character is its stroke contrast (it has thicks and thins). There is no sans serif in the Google Web Fonts library that is even remotely like it. In fact, I can’t recommend most of the Google fonts because 80% are poorly designed and even worse when viewed with Windows browsers.

Why not go with the real thing? You can get it from the source (Monotype/Linotype) at fonts for discord.

Bitstream’s version of Optima, Humanist 601, is also available for web use. Though, like many of the others below, I wouldn’t recommend using it at small sizes.