Kakao Company is truly dominating the South Korean industry, being a staple in the electronic industry, especially with all their phone applications. The main one I love to use is their mobile messaging app,
NaverMaps
NaverMaps is basically the Korean version of Google Maps, being very useful in finding what buses or subway you have to take to get to your destination. It has an English-friendly user-interface, stating the locations and subway stations in English for easier usage. Simply typing in your location, you can figure out the best transportation route to take as well as any alternative buses/subways with their estimated arrival time. However, it may be quite confusing at first due to differences between English and Korean words in real life, so it would be great if you know how to read hangul. Another alternative to NaverMaps would be KakaoMap, but I feel like there are some discrepancies using English to find locations in that app, so I would recommend NaverMaps more. The Google Maps app is limited in Korea, not being able to show walking distances and locations, therefore, NaverMaps would be a better app to have.
Kakao Apps
Kakao Company is truly dominating the South Korean industry, being a staple in the electronic industry, especially with all their phone applications. The main one I love to use is their mobile messaging app, KakaoTalk, which was used often during my study abroad at Yonsei University. It is a great way to get in contact with your friends since it is basically free texting and calling through the application (just pay for your data usage!). Even being on 2G speeds with my T-Mobile international data plan, KakaoTalk loaded quickly and messaged instantaneously, excluding pictures and videos sent in the chat. In addition to KakaoTalk, they also provide many other applications for users with KakaoMaps, KakaoMetro, KakaoBus, and KakaoTaxi. However, with the usage of NaverMaps, I found these applications unnecessary since the ETA of buses and metros are already stated.
Papago
Papago is basically an alternative to the Google Translate app; it is under the same company as NaverMaps, which is Naver. I am not sure how well it translates between English and Korean, but due to its background in Korean, I believe that it would provide closer translations rather than Google Translate. The first time I went to Juno Hair Salon, my hairstylist used this app to translate to figure out what I wanted for my haircut/dye; it served as a great liaison between us for communication.
MangoPlate
Unfortunately, I only heard about this application towards the end of my stay in Korea by watching Joan Kim, a California-raised YouTuber living in Korea with beauty videos on her main channel @joankeem and daily vlogs on her second channel @joanday. By being immersed in her vlogging channel, I was exposed to this app that she and her friends use, stating that it is like the Korean version of Yelp. With a great English interface, you can select the location you wish to search for or have the app search for foods in nearby areas. There are reviews and pictures of restaurants and cafes to help you decide where you want to eat. When I go back to Korea, I definitely will try to use this more often!