[ynak]

I also want to build a self-host data completion proxy on my own. But the more web sites support SSL connection, the less impacts on the data completion in the future I think. WWW are moving toward the all encrypted internet, so is this kind of technologies a temporary stuff? Or is there a possibility to reduce data transfers under the SSL protocol?

[venomsnake]

You can mitm yourself with no problem. Firefox has the option to ignore pinned certificates if you have valid user installed certificate as trusted root.