top of page

Mobile App 
UX/UI Design

for selling used books

USED is the app that allows people who want to sell their second-hand books, CDs, or DVDs to put less time and effort to sell them. It helps people compare the prices of all the book stores at the same time, they can sell them at better prices and be smart with money. 


Research, Wireframe, User Flow,

User Persona, UI Design

My Role

Project Duration

5 weeks / July 2019 


​​​​​​Mainly we start the project from our own experiences. When I was preparing to move to Singapore, I had to reduce as much stuff as I could and books were the first thing that I had to get rid of. I decided to sell them to book stores in Korea. Each bookstore has its own selling system on its apps but the prices that people can get vary based on every bookstore’s criteria of second-hand books. 

I had to compare the prices of every book through each bookstore’s app and it took a quite long time and it was a lot of hassle as well. It sparked the idea for this project.

If all the book stores can be brought together on one platform, then the users can sell their books more easily.

How might I sell used books easily at better prices?

Current User Problem

What's Your Difficulty?

  • Tiresome to search each book on every bookstore app ​​​​for better price

  • Takes time to the repetitive task one by one

  • Hard to compare the prices all at once 

  • Difficult to keep track of the price fluctuation in real time

Artboard – 5.png
Artboard – 6.png

▷ Time-consuming process to find the best place to sell 

When a user has some books that they want to sell bookstore, they have to access each 4 bookstore’s app or website to find out the best price they can get. They have to do the same process and sort every book by themselves. Then they access every bookstore again to make a booking to visit.


FBP (Fixed Book Price System)

Due the Fixed book Price policy that was implemented several years ago, the used book sales have been significantly growing. 

Since the sales of new books have gone down, major book stores have tried to expand the second-hand items market by providing the service selling and buying used items or opening the store only for the used stuff in order to restore their sales loss.

Artboard – 7.png
Artboard – 8.png

Minimalism Interior Trend

For the last few years, minimalism Interior trends and simplicity of lifestyle have caught a lot of people all over the world. 

Korea is no exception. Many people who are feeling overwhelmed by their possessions have become interested in minimalism and those people try to minimize their stuff to pursue a simple life. Books are one of the items they want to get rid of. 


Who is it for?

Artboard – 9.png

Semin is a college student and works at a fast food restaurant as a part time job. He is interested in many things but he can't afford it so he tries to be smart with his money using second-hand markets online. 

Books are one of the items that he buys and sells quite often. 

However, it is too much of a hassle to find the place that he can sell them at good prices so he does it when there are several books collected.

Choi Semin (24) / student

Jiwoo is a housewife who has 2 children. She has quite a lot of books for children and there are many books that her kids will no longer read. So she tries to organize them regularly. She knows there are several bookstores where she can sell books but she has no time to sort out such many books. So she has sold all of them off to only one bookstore, even though she knows she could've gotten more money.

Artboard – 10.png

Choi Semin (24) / student

User Goals

What do they want?

Save their time and effort

Find the best place to sell their items

Easy to compare the prices

Easy to take their items to each store


How might I create an app that can save time and effort?


If users can see the information from all bookstores simply by one-time barcodes scan, ​​​​​​​users will not need to repeat the same task over and over again.


If it helps automatically sort items by the best price, ​​​​​​​users will not need to go through all the hassles of comparing every single book. 


If it helps users complete the process in one sitting by providing even the information about the place they would go, ​​​​​​​it will save them a lot of time and effort.

User Scenario


The prime function of the app is searching and selling, so I wanted it to be a one-stop process. 

When there are some books to want to sell, a user open this app and scan the ISBN barcode, which is on the backside of a book, the book will be shown on the screen and it requires to simply check the condition of a book. 

After scanning all the books, the books the user scanned will be sorted by a book store that offers them a better price.

The user can see how much they can get from selling those books in advance, and also check the place nearby. Based on the way they want, they can make a booking pickup or the date and time of visit.  



Design System

Artboard – 12.png

Refining Design

I conducted a usability testing with a high-fidelity prototype.

I gave certain tasks to participants and observed the participants behaviors.

iPhone X, XS, 11 Pro – 21.png
  • It's hard to see whether the book I added or not after scanning

  • The button is invisible so I don't know what to do



  • combined the pages ; scanning page and the list of books  

  • Put the fixed button so that they can see it all the time

search -2 – 39.png


  • The page looks complicated​​. There seem too many things in this page

  • I have no idea what to do next

  • I can't find the button


  • Separated the pages with 

  • Put the fixed button so that they can see it all the time


Mobile App 
UX/UI Design

for selling used books


Easy to compare

Users don’t need to access every single bookstore. All they need to do is just scan the barcode of the book. It shows the user the prices of the book that they can get. The prices can be different whenever the users refresh it because the price information is based on real-time information.


Easy to sell

Once the user puts the books on the list, the app sorts the books by the best prices automatically and they can move the book to the tap of another book store by drag and drop the book card. Then, they can make a booking the date for visit or pickup schedule. 


Despite we were unable to promote this app, many people have searched this app on their own and utilized it. Many users seem to be using it in the way I expected and left positive reviews. 

Artboard – 3b.png

The takeaway

It start with my personal experience and inconvenience but I learned that people having the same experience by researching and they needed the better way to do it. I felt rewarded from users’ positive reviews and their feedbacks. 

iPhone 13, 12 Pro – 2.png
bottom of page