Foreign Currency Converter — A Case Study for A Banking App

Jennifer Handali
6 min readNov 29, 2023


A Case Study for a Banking App — Bank Ajib Indonesia

Hi everyone, I hope you are enjoying my case study writings. This time I challenged myself to craft an interface of a Banking app that has a feature to save and convert our money to other foreign currencies.

Bank Ajib Indonesia is not a real bank (at least for now), but it is a name I will use to refer to the app. Without further ado, let’s follow through my design process below!


Bank Ajib Indonesia is one of the emerging digital banks with a mission to provide seamless financial solutions. One of its features allows users to save and transact with multiple foreign currencies with a single account.

This feature is great for travelers like Budi to convert their money from IDR to another foreign currency according to their travel destination.

User Story: As a Bank Customer, I want to view the current Thailand Baht buy rate so I can buy Thailand Baht with a considered amount.


Problem Statement: How might we help Bank Ajib Indonesia customers purchase another foreign currency in the app?

Proposed Solution: A Foreign Currency Converter that connects with the Bank Ajib Indonesia e-wallet so users can buy or sell the desired foreign balance in a single app.

Step 1: Understand

When opening an account in a local digital bank, users usually have their local currency (in this case Indonesian Rupiah) as the main savings & transaction currency. However, the money saved in local currency cannot be used in other countries when they are traveling.

Before digital solutions were available, users had to spend their time and energy going to money changers stores physically to trade their money to other foreign currencies. However, the process is not always pleasant as different money changers can charge different amounts for the purchase.

After their holiday, users also worry about what they have to do with the leftover foreign money. Of course, opening another foreign bank account was not a solution for their short-term use.

To understand more about the users, I list down their needs, pain points wishes towards this Foreign Currency Converter.

Bank Ajib Indonesia Customers — User Persona

Step 2: Define

Using previously collected information, I define the user goals and plan the design to help the users achieve those goal while eliminating other worries they have.

User Goal: As a Bank Customer, I want to view the current Thailand Baht buy rate so I can buy Thailand Baht with a considered amount.

Design Goal: How might we help Bank Ajib customers purchase another foreign currency in the app?

Keywords: Easy, Safe, Transparent, Affordable, Flexible

Step 3: Ideate

I mapped out each steps the user will have to do when exchanging their money to foreign currency (i.e, exchanging Indonesian Rupiah to Thailand Baht).

Bank Ajib Indonesia Customers — User Flow

For inspiration, I collected some references from the regulators and other digital banks.

Reference 1: Bank Indonesia Foreign Currency

I checked Bank Indonesia’s published list of foreign currency buy and sell rates to understand how the system works and the current numbers.

The sell price will usually be higher than the buy price and placed first in order.

Bank Indonesia Foreign Currencies — Buy and Sell Price Table

Reference 2: Wise & Jenius Foreign Wallets

I also checked other digital banks that already support similar problems. Usually, they would have individual wallets so users can keep track of each foreign money easily.

The wallet display would have helpful visual cues (like names, flags, or landmarks) to differentiate the wallet easily.

Wise and Jenius Foreign Wallets

Step 4: Design

In the design process, I started by sketching some key screens of the foreign currency purchase flow in my notebook to translate my ideas into wireframes.

Bank Ajib Indonesia — Pen and Paper Wireframe Sketch

As always, let’s take a look at the digital version so you have a better view of the design.

Bank Ajib Indonesia — Digital Wireframes

I imagined that the Homepage would be a quick view of our account balances, quick action menus, latest updates, and other helpful, dynamic information.

The other key screens that I sketched would be the flow to convert the money from Indonesian Rupiah (IDR) to Thailand Baht (THB) and review the balance again in the wallet.

With its unique name, I imagine Bank Ajib Indonesia’s brand as something that is youthful and magical. So I picked bright and fun colors to match its personality.

I also keep the UI clean & minimal so user don’t get overwhelmed seeing different numbers everywhere.

Bank Ajib Indonesia — UI Kits and Project Components

Let’s dig into more details on the design!

On the Homepage, users will have access to their main IDR wallet and other different foreign wallets. I also provide multiple entry points for users to access the Foreign Currency Feature.

Bank Ajib Indonesia — Homepage

Clicking on the Add another Foreign Wallet or Convert menu below their active wallet will bring users to the Convert page. Users still can adjust the foreign currency and the desired amount they want to purchase. Before placing the order, they will be asked to review the order and verify their identity first.

I use the word “Convert” because it isn’t always about buying, but can also be about selling the intended foreign currency.

Bank Ajib Indonesia — Convert to Foreign Currency

It is also important to address that orders are not always successful. So I also added some negative states for example. Users have to meet the minimum deposit amount for a convert transaction and the action can only be completed during the operational hours as regulated.

Bank Ajib Indonesia — Error States

Finally, I topped it off with the design for the completed state. The converted money will be added to the destination wallet balance.

Bank Ajib Indonesia —Updated Thailand Baht Balance

Let’s have the final look of all the screens!


There are still a lot of features connected to this foreign currency converter, such as sending and selling foreign balances. However this case study only focused on one user story around purchasing, so it is not covered here.

I believe the design itself can be enriched with more improvement in the future, like:

1. Foreign currency rate chart: users can view better details on the price fluctuation over time

2. Price Alerts: users can be notified when the buy or sell rate hits desired price, so they can transact at a better value

3. Promotions: when banks have a special campaign or voucher enabled to give users discounts on the conversion fee.

4. Micro-interactions: animations and illustrations to make the entire journey more attractive.

Thanks for reading!

All my case studies are my practice towards Design Thinking and Product Design skills. I hope you enjoy reading this and find the proposed solution can provide a seamless experience for saving and converting foreign currency in single app.

👋 I’m Jennifer Handali, with 5+ yoe as Product Designer.
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Jennifer Handali

An ENFJ with 5+ years of experience as a Product Designer. Love to share my thoughts and processes.