How interesting that there are a lot of comments about apps but when I read "tools", I instantly thought about gadgets like a power bank, a smart watch or some sort of a really powerful flashlight for camping. And all of them matter so much for safety - power bank is your phone's longer battery life, and it's the number one item I pack for any trip. Smart watches have fall detection, like someone already mentioned, monitor heartbeats, walk miles, and sleep quality (even apnea in the latest apple watches), which can be useful too and is related to safety. A flashlight can seem obvious but for camping, it can be so valuable for different reasons - from spotting wild animals to scanning terrain when you walk the path, because a phone flashlight consumes the battery like there's no tomorrow. And so on with portable water cleaners, car gadgets, medical items etc etc.
Just curious, who else read "tools" as I did, and if so, what would you add?