By default, WhatsApp saves any images you get sent to your iPhone’s Camera Roll. While this might seem like a good idea, if your friends are the kind of people who share… questionable… photos and GIFs, you may not want them automatically getting mixed in with your family photos.
The fix is simple—though it’s different on iOS than it is on Android.
On the iPhone
iPhone users have it easy: this setting is built in to WhatsApp. Open WhatsApp and go to Settings > Chats.
Turn the Save Incoming Media switch off and now photos won’t automatically get saved to your Camera Roll.
To save a photo you want to keep, open it and tap the Share button. Tap Save and it will get saved to your Camera Roll.
Unfortunately, WhatsApp does not have a dedicated setting for this on Android. However, you can use this trick to hide WhatsApp’s folder from Android’s gallery apps. Just create a .nomedia file, as explained in that tutorial, in WhatsApp’s pictures folder, which you’ll find in the WhatsApp > Media in your file explorer of choice.