In no particular order and also updated sporadically as I find new resources:
1. Freecampsites.net
This resource can sometimes be a little outdated, so make sure you always have a backup plan, just in case the information on a particular spot is false.
2. NFS Ranger Stations
People often overlook the benefits of talking to Rangers in person. Rangers are not just people who enforce NFS rules, but they’re also an incredible resource full of information about the best places to Dispersed camp!! Remember that a smile, and kindness goes a long way.
3. National Forest Service Interactive Map
4. Bureau of Land Management Interactive Map
5. National Parks Service Website
6. Allstays Camp & RV App
7. Campendium
8. ONx Maps (pay)
9. US Public Lands App
(available on Android and Apple)
10. Ultimate Campgrounds USA and Canada
11. The Dyrt
I also highly recommend you head on over and check out Staci Wilt’s blog post about how she finds great campgrounds (paid and free).