[dahtguy]

While manufacturer's may have very small deviations in their footprints, by and large almost every IC conforms to some kind of JEDEC compliant package. From there, IPC-7351B [1] has mathematical recommendations on footprints ranging from Class 1 (minimum required) to Class 3 A/B (ultra-reliable). Obviously those are just suggestions, but manufacturers have been aligning more and more with them. My daily ECAD/EDA tool is Altium, and I can't remember I had to manually make an IC footprint. I use their IPC Wizard[2] to make it all for me. As a bonus, I get a nice STEP model too with my export.

[1]: Can find it here http://shop.ipc.org/IPC-7351B-English-D or likely in PDF elsewhere. [2]: https://www.altium.com/solution/pcb-footprint-library