Transforming a Large Monolith into a Future-Ready Workforce Management Ecosystem

Success Story

A leading staffing agency specialising in connecting highly skilled professionals with facilities across the UK faced an urgent need to modernise its platform. Initially developed as a sizeable monolith, the agency’s system covered everything from onboarding new talent and managing client requirements to scheduling shifts and processing financial data. While the monolithic approach provided a unified codebase, it also limited scalability and agility. Recognising the potential risks of a sprawling monolith, the agency sought to simultaneously maintain the existing system, develop essential new features, and carefully transition critical components into microservices.

Up to 40% Quicker
Order Processing

25% Increase
in Sales

20% Drop
in Staff Costs

Challenges

Maintaining a monolithic architecture imposed significant constraints on the company’s ability to innovate and scale. Whenever stakeholders requested enhancements—such as integrating a new payment method or expanding eligibility checks for specialised roles—the tightly coupled modules made it cumbersome to introduce changes. This led to longer development cycles, complicated regression testing, and an ever-growing risk of system-wide bugs.

Performance bottlenecks also became a critical issue. The platform experienced sudden traffic spikes whenever facilities created large volumes of urgent shifts. Because the monolith’s components were all interdependent, heavier loads in one area could degrade performance across the entire application. Similarly, multiple data stores were consolidated into a single database, making it difficult to scale specific services that were particularly resource-intensive. Developers also found themselves spending more time negotiating dependencies with one another, slowing the pace of both new feature development and routine maintenance.

Moreover, the organisation recognised that future innovation—such as adopting AI-driven scheduling or advanced analytics—would require the ability to deploy new services independently. While the monolith had served them well initially, the risk of technical debt grew with each release, prompting a strategic re-think of their architecture.

Our Solution

In order to address these challenges, the development team took a careful, dual-pronged approach by optimising and stabilising the existing monolith while methodically carving out functionalities into microservices. In the initial phase, they conducted a detailed performance audit to identify the most pressing bottlenecks. This audit led to database query optimisations, the introduction of more efficient caching mechanisms, and the refactoring of critical endpoints. These improvements immediately enhanced response times, ensuring users could continue to rely on the platform for day-to-day operations without lengthy downtime or disruptive system overhauls.

Parallel to these performance fixes, the team devised a plan to split off specific services that would benefit most from independent scaling. Drawing on a container-based strategy, they used AWS EKS to isolate certain modules—like shift scheduling and financial processing—into standalone microservices. Each of these new services could then be deployed, updated, and scaled independently, reducing the risk of broad impacts on the rest of the system. The team introduced a lightweight messaging layer using services such as AWS SQS and SNS to ensure smooth communication between the emerging microservices and the larger monolith.

To maintain consistent security practices and data governance, the agency centralised authentication and role-based access controls. Even as services split away from the core application, all interactions adhered to the same security standards. This cohesive approach fostered seamless user experiences despite the architectural changes in the background. Continuous delivery through ArgoCD further enabled rapid, reliable deployments. Whenever a service was modified or added, automated pipelines ensured quality checks were performed before going live, thus greatly reducing the chances of unexpected issues.

Throughout this process, the team followed an iterative strategy. Rather than attempting a massive rewrite, they replaced small slices of monolithic functionality with microservices using a pattern often described as the “Strangler Fig.” This approach allowed the development organisation to test new services in production gradually, collect feedback, and pivot quickly if needed. Over time, the monolith’s footprint shrank as individual components moved out into more manageable, self-contained services.

Results & Business Impact

Enhanced Scalability
- Targeted Services on AWS EKS: High-volume features (like creating urgent shifts) now run independently, easily scaling up during demand peaks.
Faster Feature Development
- Up to 30% Reduction in Release Cycles: Isolating services means smaller, more frequent updates with fewer dependencies.
Improved System Performance
- Optimised Queries & Caching: Strategic refactoring of the monolith cut response times, offering a smoother user experience across the platform.
Reduced Operational Risk
- Phased Migration: Introducing microservices gradually minimised downtime and allowed teams to catch issues early, mitigating the impact on end users.
Future-Proof Foundation
- Modern Architecture Roadmap: The agency now stands ready to integrate AI-driven staff matching or advanced analytics without reworking the entire codebase.

Looking Ahead

By strategically maintaining the existing monolith while carving out microservices over time, the agency has laid the groundwork for robust, flexible growth. As each microservice matures, the organisation can further streamline collaboration between development teams, introduce cutting-edge features, and adopt modern best practices without risking the stability of its day-to-day operations.

With the right balance of cautious planning and incremental transformation, the agency is well-positioned to expand into new specialisations, onboard more facilities, and continue setting the industry standard for seamless staffing experiences.