ThinPic Photo Optimizer
Several years ago, I wrote about JPEG Wizard Online Optimizer as a solution for saving space by shrinking some of your photos. There are plenty of reasons to keep full sized versions for archival purposes, but for things sharing online or storing on a smartphone, shrinking photos can make a huge amount of sense.
In the years that have passed since I originally wrote about JPEG Wizard, the company reinvented itself and now offers a solution to meet the needs of the smartphone market.
Available as both an Android and iOS app, ThinPic will analyze photos on your smartphone or tablet and optimize them to use less space. You can optimize for retaining image quality while still reducing size, optimize on size alone, or choose a balanced approach. The company claims you can free up as much as 60% of the space consumed by photos on your smartphone or tablet, I'm guessing your mileage will vary but it will definitely give you more space. I recommend testing ThinPic with a few images before settling on a favored approach. The app is free for three photos per day or you can upgrade to unlimited optimizations for $1.99 as of this writing.