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Timeline: March 2023, 4 weeks

Tools: Figma / Miro / Photoshop

Role: UX / UI Designer end to end

Adding a payment feature to reduce stress when sharing expenses


Splitwise is a free tool that keeps track of shared expenses and balances with housemates, trips, groups, friends, and family. Splitwises’ largest customer base is in the USA. These users have access to a different set of features than those based in Europe and else where. Understanding how European customers are using their services and what new features are desired would be critical in growing this audience. The products current utility was investigated for feature additions to improve user satisfaction.

The problem

Users are unable to pay each other directly within the application.

The process


  • Secondary research

  • Competitor analyses

  • User interviews

  • Affinity maps


  • Personas

  • User journey map

  • Task flow

  • Information architecture


  • Wireframes

  • UI design

  • Prototype

Usability Testing

  • Usability testing

  • Iteration

Competitor analyses

Products have differentiated themselves within the market by optimising their services to particular situations under which expenses are usually split. The application “Tab” for example has a receipt scanning feature that enables users to split a dinner bill by selecting the items users purchased. This is the only feature that the application has. None of the products allowed users to pay each other within the application.


Makes it simple to split expenses, track borrowing and lending over time.

Calculate shared expenses with a particular focus on travelling.

Only splits dinner bills.

Makes it simple to manage expenses with a particular focus on travelling and living together.


The high number of features may overwhelm users.

Only 1 expense group can be made for free. There is also no web based platform.

Tab only has a single feature. Saving previous bills is behind a pay wall.

PDF and CSV files are behind a paywall.


Versatile unique group creation to split expenses.

Bills can be settled in more than 150 currencies. Making the application very useful for travelling.

All users take part in splitting the bill. Additionally it calculates the service charge and tax.

very simple onboarding and expense adding requests for other users is done via share links.

The solution

I asked myself if a direct payment method could be integrated within the application. This would enable uses to not only calculate their shared expenses but also settle outstanding debts with each other without ever leaving the application.

High level design goals

  • Offer users a fully integrated payment system.

  • A payment system that fits within the existing “settle up” user flow.

  • Support user uptake of the new payment system.


I conducted user and payment systems research, as they were both critical to the project’s value proposition.

User research affinity map

I conducted five user interviews to gain insights into the key pain points they were facing.


Absent direct payment method is frustrating. Difficult conversations persist around expenses due to repayments. Users have issues with group and individual expense repayments.

The primary function of the product, keeping track and remembering expenses, is highly valued by users. Multiple expense sharing scenarios are also used by most users.

Secondary research

My secondary research was focused on identifying applications that had integrated payment systems. The payment system that was used in Vinted showed the greatest potential to be integrated within the Splitwise “settle up” user flow. “Settle up” refers to when users pay each other the calculated difference of their shared expenses. UK legislation dictates that if a service offers it's customers the ability to move money between two accounts, they must meet a list of legal requirements. Due to the complexity of these requirements necessitating additional professional support, the integration of a payment system can be very expensive if a business seeks to do this by themselves. In the case of Vinted an independent service provider that specialises in the handling of money has been contracted to support such business needs. The service provider is Mangopay. Mangopay enables businesses to design their own payment system. In the case of Vinted users are able to link their bank accounts and pay each other directly. Users are also able to hold money within the application and use this credit to make purchases and sales.

Key findings

The primary function of the product, keeping track and remembering expenses, is highly valued by users. Multiple expense sharing scenarios are used by most users. Absent direct payment method is frustrating. Difficult conversations persist around expenses due to repayments. Users have issues with group and individual expense repayments.

“My partner sent money to the wrong account because she had to leave the app”

Dan, research participant #3

Defining the audience and application features

The findings show that the primary function of the application, sharing expenses, is successfully retaining users, however, adding an in application payment method would complete the service, resolve some of the current pain points and attract new users.


User research, strongly indicated that the designs should seek to fulfil the needs of the following 3 key personas.

User flows and navigation

The applications established information architecture was used to identify the level on which to add the new features. In order to design a fully integrated payment system, 3 key user flows were identified.

1. Payment 

2. Withdrawal account and payment account

3. Withdrawing

Ideation and design

Splitwise has established brand guidelines, which include a colour pallet, typography, logos and brand attributes.


Low fidelity wireframes were produced by carefully integrating existing examples of payment systems into the current Splitwise designs.

High fidelity design

Once the added features were optimally integrated, I began to create the high fidelity designs and a prototype. At this stage I revisited my user research key insights to ensure that my designs addressed “how I might”:


Maintain the current functionality of the product that users place most of the value, by utilising existing user flows.


Enable users to pay each other directly within the application by integrating payment methods.

Reduce difficult finance related conversations, and assisting users with group and individual expense repayments, by providing payment confirmation for reassurance.

Usability testing

Usability tests were conducted with the following three goals:


  • Users ability to set up, pay and withdraw with their bank account details.

  • Users ability to “Settle up” their expenses by using the integrated payment system.


  • Users ability to locate and understand the functionality of the balance feature.


The “settle up” payment system makes sense to users and helps them to effectively pay each other back for sharing expenses, reduce confusion and stress.




The wording was changed from “You paid” to “You’re paying” to make it clear that the payment had not cleared yet.

I added an underlined button on the payers bank information as users repeatedly tried to select this information. This button will enable users to change their bank details. 

The wording was changed from “Add card” to “Add new payment option” and “Change bank account’ to “Change withdrawal account” to help users have a clearer understanding as to how their card information would be used. I also added an information icon next to “Change withdrawal account” that will give users access to a new information screen that explains the “withdrawal account” functionality. 

I added an information icon next to “Pending balance” that will give users access to a new information screen that explains the “Balance” functionality to help support their understanding of the feature.


The payment feature will allow users to pay each other in the application. This increased utility will reduce user fatigue or frustration by removing user money transfer errors.

The greatest challenge of this project was adding a feature that would bring greater value to the product whilst not disrupting the primary function which has already proven to be very useful for attracting and maintaining its large user base.


After contacting the Splitwise team in regards to this project, I was asked if I could present this case study to some of the team members. The interest that they showed in this project would further suggest that the addition of a payment system feature for the UK is something that Splitwise is considering.

“We really enjoyed your presentation and learned a lot”

Splitwise team members: Leanne Gunn, Design Manager, Sarah Shevon, Business Operations

Looking forward

Further feature designs need to be created for the payment approval system for users receiving funds.
The edition of this feature could result in the following product wide changes:


  • New methods of shared expense calculations.

  • Agreed budgets “pots of money”.

  • Monthly management systems.

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