Caffenol
Caffenol is a photographic alternative process whereby caffeine, sodium carbonate and optionally Vitamin C are used in aqueous solution as a film and print photographic developer.[1][2]
Other basic (as opposed to acidic) chemicals can be used in place of sodium carbonate, however sodium carbonate is the most common.[1]
There are many formulas for caffenol. All are based on preparations which contain caffeine (i.e. coffee and tea) and a pH modifier, most often sodium carbonate.[2][3] The chemistry of caffenol developers is based on the action of the reducing agent caffeic acid as well as caffeine.[1]