DustFox finds duplicates, blurry shots, old screenshots, WhatsApp repeats and oversized videos, then builds a plan for exactly the space you need. Similar photos are grouped and the best keeper is chosen by sharpness and exposure; videos are re-encoded with HEVC at the same resolution. Everything runs on your iPhone: no account, no uploads, no data collected, works offline. Free to try; Pro is $19.99 once or $9.99 a year, with Family Sharing.
