Unfortunately the quality of photo is not good as I had to crop and lighten it and had a low pixel resolution. 
This tiny little fly on the window sill had no chance as the tiny spider suddenly pounced on it.  The jumping zebra spider (Salticus scenicus) is common but seldom noticed as it is well under a centimetre in length. Instead of making a web it will stalk its prey and then jump and paralyse it with its venom.  It has a remarkably good eyesight with eight eyes with an impressive pair at the front which are able to move around and focus on its prey, acting like telephoto lenses.  Later I watched another outside but it caught nothing.