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System design

System Design

Architecting scalable, resilient digital systems that integrate seamlessly with your existing infrastructure and grow with your organisation

Mortar's System Design practice brings together technical architecture, data engineering, and strategic planning to help organisations build digital systems that are robust, maintainable, and fit for purpose. Whether you are starting from scratch, modernising a legacy platform, or integrating new capabilities into an existing ecosystem, we provide the architectural thinking and hands-on expertise to deliver systems that work at scale.

How it Works

We take a pragmatic, evidence-led approach to system design. We start by understanding your existing technical landscape, your organisational constraints, and the outcomes you need to achieve. From there, we develop a clear architectural strategy — one that balances technical best practice with the realities of your context, budget, and timeline.

  • Technical discovery: Audit your existing systems, data flows, and infrastructure to identify constraints, risks, and opportunities for improvement.
  • Architecture design: Define a clear system architecture that meets your functional and non-functional requirements, including scalability, security, and maintainability.
  • API and integration design: Specify how your systems will communicate — internally and with external services — using modern, standards-based approaches.
  • Delivery and implementation support: Work alongside your development teams to translate architectural designs into working systems, with clear documentation and quality standards throughout.

Key Features

Our System Design solution covers the full breadth of technical architecture and engineering practice.

  • Technical Discovery and Audit We begin with a thorough assessment of your current systems, identifying technical debt, integration gaps, and areas of risk. This gives us a clear baseline from which to plan and design.

  • Scalable Architecture Design We design systems built to grow — using cloud-native patterns, microservices, and event-driven architectures where appropriate. Our designs prioritise resilience, fault tolerance, and operational simplicity.

  • API Design and Integration Strategy We design clean, well-documented APIs that make your systems easy to integrate and extend. We apply RESTful and GraphQL patterns, and can advise on standards such as the NHS Login API or GOV.UK Pay where relevant.

  • Data Architecture We design the data layer of your systems with care — defining schemas, storage strategies, and data flows that support both operational needs and analytical use cases. We ensure data is structured, governed, and accessible.

  • Security and Compliance by Design Security is embedded in our architectural process, not bolted on at the end. We design systems that meet the requirements of Cyber Essentials, GDPR, and sector-specific standards from the outset.

  • Technical Documentation and Handover We produce clear, maintainable architectural documentation — including system diagrams, data dictionaries, and decision logs — so that your teams have everything they need to operate and evolve the system over time.

Case Study Highlight

Mortar designed the technical architecture for a case management platform serving tenants at risk of losing their homes across London. We built a scalable, API-first system that integrated with existing housing management software and enabled real-time data sharing between local authorities and frontline workers. Read more

Why It Matters

Poorly designed systems are one of the biggest drags on public sector productivity. Fragmented data, brittle integrations, and systems that cannot adapt to changing needs create enormous operational costs and limit an organisation's ability to deliver better services. System Design addresses this at the source — by making the right architectural decisions early, organisations avoid the compounding cost of technical debt and build platforms that support rather than constrain their work.

Good system design also enables better data use. When systems are designed with data quality and accessibility in mind, organisations gain the insight they need to improve services, demonstrate impact, and make evidence-based decisions.

Get in Touch

If your organisation is grappling with legacy systems, integration challenges, or the need to build new digital infrastructure, we can help. Get in touch to find out how our System Design practice can set your technology on a firmer, more sustainable footing.

Get in touch