I make most of my jams without pectin. Apples and mangoes are naturally high in pectin. I've done these without any pectin: Apple butter, Apple Jelly, Pear butter, Strawberry, Strawberry Rhubarb, Blackberry, Triple Berry, Mango lime, Mango Raspberry, Peach Melba, Nectarine, Cranberry/Apple/Pineapple, Raspberry, and I'm sure there's more.
I made a Carmel apple jam with pectin last year, I really want to try it without pectin this year. (Hopefully I'll get enough apples)
If a recipe calls for the pectin, I just leave it out - it takes longer to cook, but I haven't had much issue getting it to set. (except apple jelly, that one is tricky)