Probably the most basic app to use when booking accommodations but there is a good reason why I love booking with booking - when you book more than 2 accommodations within 2 years you can already get 10% on some following reservations. It's called "Genius booking status" and you can also reach the 2nd level with even more benefits when you book 5 accommodations within 2 years. Also, for those who have an Amazon Prime account, you get 10% of the costs back to use it for the next reservation, how cool is that? So with a Genius booking status and an Amazon Prime account you can save lot of money when booking with booking.com!
Now I'm working for Lufthansa so I rarely use the app, but back then when I was looking for the cheapest flight I always used Skyscanner as they've got a really nice calendar view where you can check the cheapest flights in a whole month, perfect for all those who are flexible with the dates.
Been is an app where you can select all countries you've already visited and it gives you an overview per continent and worldwide how much percent and how many countries in total you've already travelled to. So when you're also a frequently traveller and somebody asks you where you've already been, it might be easier to just open the app ;)
Super cool app to check different travel options between two locations. It gives you an overview of all possibilities like flight, train, ferry, bus, taxi, rental car, etc. including timeline, prices and direct link to the website to book the journey. Especially when backpacking through a country instead of staying at one place it's super helpful!
Always good to get some advices about local restaurants that are recommended and also before booking a hotel I check the reviews on TripAdvisor to make sure that it's good. Also to get an idea of day trips, waterfalls in the area, etc. it's helpful. I've got a list for almost every country I want to visit in the near future with some restaurants, see sights and trips marked as favorite.
Even the tours might be little bit more expensive sometimes it is a good start to see which activities are available at the destination. Also, if you book via GetYourGuide, they have got an excellent customer service!! One reason, why I always prefer to book with GetYourGuide directly. And you can often find discount codes, e.g. via Corporate Benefits.
Whenever I travel I love to send some postcards to friends and family but sometimes it happened in the past that we postcard never arrived so now I'm using this app to use my own photos for the postcard for a really small money it will directly be send within 2-3 days. You can write the whole text via phone what also makes it easier in case you want to write a longer text :)
As far as I know currently it's also useful in the US but if you're there you don't want to miss it - it gives you an overview of all available parking lots around incl. information about pricing, opening hours, etc. - especially in bigger cities like San Francisco, Miami, etc. it helped me to save lot of money.
Google Maps? Yes! One of my favorite apps! Whenever I see a place I would love to visit in a documentation, on Instagram or anywhere else I directly mark this place in Google Maps with the yellow star. Hotels I would like to stay in will be marked with the red heart. Sometimes I also just scroll around an area to search for the "photo"-icon that shows that there is something special to see and then I check whether it's worth it to mark it with a star. Or I search for "waterfall" in a specific area to get a list of all waterfalls around and then I check which one I would like to see and save it. This way I've got an amazing overview of places I would like to see and to stay when I visit a country as I've already saved all information for several years and marked everything.