[imaginamundo]

The is the CSS only option from Primer (GitHub design guideline). If you use in your project is the tiniest that i've ever seen and it's easy to customize via SASS. (the time that is default it's not good in my opinion, but you can change, it's a SASS variable.

http://primercss.io/tooltips/

[FezVrasta]

I'd love to use CSS for all my poppers needs.. unluckily this is not possible yet due to CSS limitations :(

[idbehold]

Those tooltips don't work on mobile.