How long can I keep my developer.

I prefer to use developers once and discard, for color or B&W. The solution for me was to get a bunch of 250ml Amber Glass Bottles to be able to mix up Xtol (20 bottles) or D76 (16 bottles) and store (in smaller bottles) with no air so it would last longer. Then I could use one shot or 1:1. Of course, it will work with any developers. I also use a layer of Saran wrap between the cap & bottle for extra sealing, just in case.

If you need some, I have lots of extra bottles.