Do attendees need to download an app to share conference photos?

No — a QR-code gallery that opens directly in a phone's browser lets attendees upload without installing anything or creating an account, which is the biggest factor in whether people actually bother.

How many QR code placements does a conference need?

More than one. A single mention at the opening keynote is easy to miss; repeating the code on badges, signage, table tents, and recurring slides drives noticeably higher participation than a single placement.

Can attendees see photos from the conference while it's still happening?

Yes, if the gallery supports real-time uploads and an optional projected Live Wall — photos appear as they're taken rather than only after the event wraps.

Is it safe to let anonymous attendees upload directly to a shared gallery?

Reputable platforms run uploaded files through automated malware and safety scanning before they appear publicly, which is a reasonable best-effort safeguard for an open-upload event gallery — worth understanding in more depth in Is It Safe to Let Guests Upload Photos to a Shared Gallery?