Every phone photo carries a hidden record: where it was taken, on what device, sometimes with what settings. Because Partyreel serves originals byte for byte, that record would otherwise travel with every download. So it's removed first, on the phone, before anything is sent.
What's stripped
For JPEG, PNG, and WebP photos and MP4 and MOV videos, the upload step removes the location and device metadata: GPS coordinates, camera and phone model, the embedded notes and tags most apps write. The metadata is cut out without re-saving the image, so the picture itself is untouched, at full quality, and the color profile is kept. Orientation is preserved so nothing ends up sideways.
Because it happens in the browser before upload, the file Partyreel stores never had the data, which also means the backup copies are clean.
What isn't
Three formats upload exactly as they are: HEIC and HEIF (the iPhone's default photo format), AVIF, and WebM video. Their structure makes blanking the metadata risky, and a corrupted photo is worse than the metadata. In practice the iPhone camera's HEIC files often carry location. If that matters for a photo, the iPhone share sheet can remove location as you export, and a screenshot or a JPEG export carries no metadata.
In one sentence: GPS location metadata is stripped from uploads, for every format Partyreel can safely edit.
Downloads
What you download is what was stored, so a downloaded JPEG carries no location, and a downloaded HEIC carries whatever it arrived with.
Nothing is analyzed
Partyreel doesn't read the metadata before removing it, doesn't run face recognition, and doesn't scan photo content. What it does keep, per upload, is in your data and deleting your account.
For hosts
This applies to your own uploads too, including a photographer's batch you add yourself. Anything you'd want kept, like camera settings for a portfolio, is gone from the stored copy; keep your own originals.