The answer to 'natural window cleaning cleaner' is to use a homemade vinegar-based solution. Mix equal parts white vinegar and water in a spray bottle, then spray and wipe the windows clean with a microfiber cloth or newspaper. This natural solution is effective, inexpensive, and eco-friendly compared to commercial window cleaners.
For best results, clean windows on a cloudy day or in the shade to prevent the solution from drying too quickly. Avoid cleaning in direct sunlight. You can also add a few drops of essential oil like lemon or lavender to the mixture for a pleasant scent.