July 2020

Online Mortgage & Insurance Calculators

Genworth is a leading provider of lenders mortgage insurance (LMI) in Australia. Genworth also provides tailored risk and capital management solutions for lender customers in the Australian residential mortgage market.

Sector: Financials - ASX: GMA - Market Cap: 1.52B - Website: genworth.com.au

What we did:

  • Structural Proposal and Sitemap
  • Visual Design and Interface
  • Content Management and administration
  • Hosting Infrastructure Design


  • Microsoft Windows Server
  • Microsoft SQL Server
  • Umbraco CMS & C# .NET
  • Bootstrap3 & jQuery front-end
  • Git Source Control


Genworth provides Mortgage Insurance products both directly to consumers and through their banking partner network. To assist their customers and partners better communicate and understand their products, Genworth required a set of online mortgage, insurance and servicing calculators.

In addition to providing online calculators through their own website, Genworth needed to provide their banking partners with an Application Programming Interface (API) that would allow them to integrate Genworth’s pricing, service fee’s and rates with their own branded mortgage calculators and services.


Mortgages and mortgage insurance rely on several variables, including the applicant’s income, deposit amount, loan amount, length of loan, interest rate, government incentives and insurance premiums. These inputs are then passed through an algorithm that calculates compound interest, repayments and insurance premiums over the lifetime of the loan.

Aside from requiring several complex algorithms, with varied calculations based on the dynamic variables, the outcomes had to be presented differently depending on the estimations the customer or partner needed to establish.

The calculators, by law, needed to be accurate, and the information clear, consistent with regulations and informative for the end customer.

Ensuring accuracy and legitimacy of inputs through Genworth’s own websites was manageable but enforcing Genworth’s own pricing and fee structure consistently through an API required special attention and logic enforcement.

To empower Genworth’s partners with an API, and encourage adoption, comprehensive documentation would be essential.


PurcellYoon proposed a centralised rates database which would include government subsidies by state, loan thresholds and various insurance premium structures. The rates database would be supplemented by an Application Programming Interface (API) that would accept multiple data inputs and return raw data calculations based on varied requests made by a client application or website.

In addition, a suite of JavaScript methods, combined into a bespoke library would be developed to assist in communicating with the API and presenting the data clearly and consistently on any website front-end authorised by the API. This JavaScript suite included unique, interactive charts and graphs.

By providing an API that performs the calculations and a front-end support library, with the enforcement of the front-end library established in the API terms of use, Genworth could ensure that external users of the API would not be permitted to manipulate input data or export data. A comprehensive Unit Testing toolset was required to ensure that the many complex and varied calculations would remain consistent and measurable during future development cycles.

To support the API and JavaScript library, a documentation portal would be provided and include detail examples of how to integrate and utilise the provided architecture.


To maximise productivity during the development phase, PurcellYoon designed the User Experience (UX) the RESTful API description and database schema as a priority.

To ensure calculations were clearly established and testable, PurcellYoon worked with Genworth to create Microsoft Excel versions of all calculations. This became an exceptional and invaluable resource for the developers and for the testers.

By thoroughly planning the architecture, and by creating simple offline testing tools, the development team was able to accurately develop a fast, consistent and secure calculation framework and platform that included comprehensive Unit Tests.

PurcellYoon completed the project within the schedule and within the budget, including the documentation website and the front-end implementations on Genworth’s own brand website.

Everything we create is personal, unique and lovingly conceived with you as our partner.

Reference: https://www.genworth.com.au/lenders/lmi-tools/buy-or-rent-calculator/

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