I built an on-device duplicate photo finder for iPhone (and why I avoided the cloud)

My camera roll had over 12,000 photos. A lot of them were near-identical shots I never cleaned up - bursts, multiple takes of the same thing, old screenshots. I tried a few duplicate cleaners. Most only caught exact pixel duplicates. That helped maybe 1% of the problem. So I built Snapsift. What it does Scans your photo library, groups photos that look similar (not just exact copies), and helps you keep one best shot from each group. scans the full library in under a minute groups near-duplicate photos side by side picks a candidate "best shot" in each group based on sharpness lets you delete the extras Why on-device only The obvious path was to send photos to a server, run similarity matching there, and return results. Cheaper to build, easier to iterate. I didn't do that for two reasons. First, privacy. Uploading someone's personal photos to a server - even temporarily - is a trust problem I didn't want to create. Second, Apple's Vision framework is actually good enough to do this lo