A Surgical Approach to Financial Services System Modernisation

Heart surgeons have one of the most stressful jobs in the world. But they don’t have time to dwell on the danger. They must operate boldly and decisively to save lives. Risk is part of the deal.  

At Critical Software, we also thrive on performing difficult tasks in demanding environments. We have spent more than 25 years working in high-stakes industries including space, aviation and defence. Our focus is on lowering the risk of change. Leaders trust us to deliver solutions that don´t require the feature freezes which often slow down big transformation projects. Instead, we focus on smooth progressive transitions. 

The modernisation of banking and insurance systems requires strong resolve and a commitment to getting the job done. Like surgeons, tech leaders recognise that their legacy technology must be updated because it is haemorrhaging money today and could lead to a genuine emergency tomorrow. But knowing this and taking action are two different things. 

We believe decision-makers across the financial services sector should take inspiration from heart surgeons. When the time comes, these modern heroes don't have time to think. They need to act.  

So, what does a surgical approach to modernisation look like and how can you apply the surgeon’s mindset to your bank or insurance company?  

1. Refactoring - Keyhole Surgery

Small, strategic adjustments to an existing system can yield significant improvements. The refactoring approach to transformation is like keyhole heart surgery, allowing for quick wins by enhancing the current codebase and optimising performance without a full overhaul. It’s cost-effective and minimises disruption to the business. 

However, just as this surgical approach may not be appropriate for all heart issues, refactoring has limitations. It might only provide a temporary fix if the underlying architecture is deeply flawed or outdated. Refactoring can also be challenging to scale if the system is too old, outdated and fragile.  

Keyhole surgery works when the existing system is sound but requires performance improvements, bug fixes, or the addition of new features. It’s perfect for organisations looking to optimise their current tech stack while avoiding the costs of complete replacement.  

2. Re-Architecture - Open Heart Surgery 

This is a deep, extensive procedure that involves carefully opening the existing system and reworking its core components. An open-heart surgery approach is necessary when the system’s foundation needs serious improvements to meet scalability, performance or security requirements. The system can be made much more flexible and future-proof by breaking down the monolith and transitioning to microservices or adopting modern frameworks. 

Like open-heart surgery, re-architecture is a complex operation. It requires a deep understanding of the current architecture and careful planning to avoid disruption.   

This strategy is suitable when the existing system is fundamentally sound but needs to be revamped to support growth, improve speed, or integrate modern capabilities. It’s appropriate when refactoring is insufficient, but a full rebuild would be too extreme. This approach is often chosen when a company must adapt to emerging technologies, deploy new business models or pursue a dramatic change in scale. 

3. Rebuild - Full Heart Transplant

A drastic but sometimes necessary option when the existing system is beyond repair or dramatic change is needed. Rebuilding core systems allows for the creation of a completely new foundation that is free from the constraints of legacy technology. This gives the organisation full control over design and can result in a clean, high-performance, future-proof solution tailored to business needs. 

A rebuild comes with the highest cost. It is a long-term, resource-intensive process that can have a dramatic positive effect on post-operative productivity. 

Rebuilding is the right choice when the current system is outdated beyond repair or when the costs and risks of re-architecture or refactoring outweigh the benefits. It’s ideal for organisations facing major shifts in their business models, technologies, and customer expectations or whenever a clean slate is needed to leap into the future without the baggage of legacy tech. 

Which approach should banks and insurance companies choose?  

Financial services organisations should select their modernisation path based on the condition of their existing systems and the scale of change required. Refactoring is best suited for relatively healthy platforms that need performance tuning, bug fixes, or new features without touching the core architecture. It’s ideal when the goal is to extend the life of the current system with minimal cost and disruption to squeeze more value from existing assets while setting the stage for longer-term evolution. 

When deeper structural changes are needed, re-architecture offers a balanced middle ground - revamping key components and modernising the tech stack without starting from scratch. This is the right choice when scalability, flexibility, or security needs have outgrown the current setup.  

In contrast, rebuilding should be reserved for cases where legacy systems are fundamentally broken or incompatible with future business goals. It’s the boldest option but also the one that enables the greatest long-term agility, performance, and innovation, which is crucial for firms undergoing major strategic or technological shifts. Choosing the right approach ensures transformation efforts are aligned with business realities, budgets, and long-term vision. 

Unlike real surgery, transformation should be considered as a journey, rather than a destination. Companies will benefit from blending approaches or changing their strategies over time to maximise value. Don’t be afraid to dig deeper, adapt the roadmap or experiment and adopt new methodologies as your modernisation program progresses.  

Choosing a partner 

A great partner is key to a successful transformation or upgrade of legacy tech. Critical Software is not afraid of difficult, demanding or even dangerous jobs. Our tech is trusted to solve tough technological challenges across industries where failure isn’t an option, including space, defence, energy, transport, and finance.  

Whether working on satellites orbiting Earth, keeping aircraft safely in the sky, or modernising financial systems for the digital age, we deliver technology that performs flawlessly under pressure. 

With more than 25 years of experience in delivering mission-critical systems, we combine deep technical expertise with proven strategies for transformation underpinned by modern architectures, scalable tools, and industry best practices.  

Our cross-sector experience means we bring fresh perspectives and robust engineering to every engagement. And our values are embedded within every line of code we write and all the solutions we deliver. We’re not afraid of danger and risk. In fact, we thrive on it. 

We are not afraid: modernise with confidence. 

Rodrigo Baptista, Principal Engineer for Digital Finance Solutions, Critical Software.