I use StartPage presently. I was about to switch to DuckDuckGo as I liked a lot of what you're doing, but then when I saw the time range search feature missing a la the following:

I decided to hang tight until you get this implemented. I like the appearance that I have set up and am all ready to start using you for my hundreds of searches a day, but I have to hang tight until you implement this.

Also a request was made for this here:
posted by <hidden> • 4 years and 5 months ago Link