For planning a camping trip
Recreation.gov is an exhaustive database of campgrounds around the country. Just plug in your destination and your arrival and departure dates, and the site or its iOS app will generate a map, with blue pins indicating available campsites and yellow pins marking those that are booked. You can also use the app to make a reservation.
Campendium compiles good-to-know information that you might not find on a campsite’s webpage, including details about toilets, cell service, and RV hookups. The iOS app also features comment sections, where reviews mention specifics such as road conditions or whether you’ll run into crowds.
Packing List will help keep you from forgetting your hiking boots, first-aid kit, fishing gear, sunscreen, bug spray, or marshmallow skewers. The Android and iOS app creates lists for various types of trips, making it useful beyond camping season.