PEX: Xamarin Builds Speed and Functionality Into Expense Management App


PEX, a New York fintech company founded in 2006 is a platform provider of next generation corporate card and expense management solutions for businesses. The PEX service enables companies to empower their workforce with flexible options for employee spending, as an alternative to credit cards or cash expenditures.

The Background

Tracking expenses in today’s world is trickier than ever, with transactions occurring with the simple swipe of a card or the push of a button. How can a company ensure their employees have the funds needed to perform essential work and still have visibility on spending? Not only that, but ensure that only the right person has access to critical business assets?

Prepaid cards have been popular in the customer sector since the 1990s; these cards paired with a mobile app for visibility and management provide a powerful option for companies looking to better track employee spending. Prepaid cards allow employers to authorize essential funds for employees to complete on-demand payments that are part of necessary business activities; for example, buying gas or purchasing necessary repair parts. Prepaid cards are not linked to bank accounts, and set specific limits on the spender.1
A mobile app allows employers to see expenses as they happen. They can allocate funds to employees depending on merchant categories, designate where and how funds may be distributed, and track expenses in real time to prevent end of billing cycle surprises.2 An app also allows employees to track and manage their own allocated funds by being able to check their balance and request needed funds on their own instead of waiting on hold for a call center. Reloadable prepaid cards also have strong "Know Your Customer" requirements; in the U.S., this means the card issuer is required to perform the same level of due diligence as if they were opening a bank account.

Of course, all of this is dependent on the mobile app’s user interface. PEX approached Softjourn for a solution to its UI issues, and Softjourn delivered by developing a convenient and easy-to-use app UI that empowers a company’s employees to tackle the work of managing their own expenses, all while keeping company assets safe.

The Need

Using their previous experience building prepaid card API, Softjourn paired with PEX to develop a user‑friendly interface for phones and tablets that allowed companies to make use of prepaid cards to better track employee spending.
Building on Adobe PhoneGap using HTML5, Softjourn developed a pair of applications: one for cardholders, and another for administrators. As funds were allocated and spent, cardholders could submit expense reports from wherever they were, whether in the office or on the road. Administrators could review spending and see exactly where the company’s money was going.
This initial solution worked well for its time, but technological improvements over the years eventually necessitated an upgrade. PEX approached Softjourn again, this time with several areas they were hoping could be improved:

  • Creating user interfaces that looked and felt like native applications;
  • Using a development platform that included pre-built UI, along with standard controls, transitions, and animations; and
  • Improving the speed of performance and upgrading security.

In addition to this, PEX requested biometrics to better prevent fraud and a receipt-capture option to help employees manage any necessary proof needed for reimbursement validation.

The Solution

Instead of building two native apps from scratch that would require separate support and additional costs, PEX and Softjourn settled on utilizing Xamarin. Despite being relatively new, the fact that Xamarin allows for a single-sourced application that has an integrated UI layer for cross-platform functionality meant a more cost-effective measure by requiring less engineering time and fewer tools. Xamarin uses C# language and .NET framework, and is paired with Microsoft Visual Studio; this means a developer has a complete solution for building, testing, and tracking an application's performance across platforms.3

Apps developed with Xamarin share 90% of the code across platforms, which also meant that adding new functionality in the future would be much easier than siloing the development of separate updates for separate apps. 

With Xamarin, Softjourn combined the two original apps into a single application that identified users via login credentials. In addition, Xamarin applications have performance metrics comparable to the original native stacks used for Android and iOS application development, which means the UI worked effortlessly; there's no detectable difference between a Xamarin and native app to the naked human eye.4


The re-built application using Xamarin allows PEX users, whether employees or managers, to enjoy rapid performance from UI that look, feel, and act like native applications. In addition, PEX benefits from a development environment that allows code sharing across all platforms, plus a development partner team that can leverage it to create great user experiences.