Legacy Software Modernisation
Transform Your Aging Systems Without Stopping the Business
We modernise legacy applications — replacing outdated technology, resolving security vulnerabilities, eliminating performance bottlenecks, and migrating to cloud infrastructure — with zero operational disruption throughout.
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Business Disruption
99.9%
Uptime During Transition
60%
Reduction in Maintenance Cost
3×
Faster Development Post-Modernisation
Legacy Systems Modernised Without Betting the Business on a Rewrite
Legacy software is not just a technical problem — it is a business risk. Systems running on unsupported operating systems, languages no longer maintained, or architecture patterns that cannot integrate with modern tools create compounding operational and security risk with every year they remain in production.
We specialise in legacy modernisation for businesses where the legacy system is mission-critical — where downtime is not an option and the system cannot simply be switched off while the replacement is built. Our approach uses proven migration patterns — strangler fig, parallel run, and modular extraction — to replace legacy systems incrementally without disrupting the operations they support.
We are pragmatic about modernisation scope. Not every legacy system needs to become a cloud-native microservices architecture. Sometimes the right answer is a selective extraction of the highest-risk components and a stabilisation of the rest. We assess before we prescribe.
- Risk-first assessment — identify the highest-risk legacy components before scoping the work
- Proven migration patterns — no big-bang rewrites, no single-day cutovers
- Continuous operations throughout — no planned downtime during migration
- Modern architecture target — cloud, API-first, and maintainable by any competent team
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Business Disruption
Legacy Software Modernisation Capabilities
A complete suite — from initial workflow mapping through to production deployment and ongoing optimisation.
Application Re-Engineering
Rebuild system architecture using modern patterns while preserving core business logic and data.
Cloud Migration
Move on-premise applications to AWS, Azure, or GCP with containerisation and managed services.
Technology Stack Replacement
Replace end-of-life languages, frameworks, and databases with modern, supported alternatives.
Data Migration & Restructuring
Migrate legacy data structures to modern schemas with validation, transformation, and zero data loss.
Security Modernisation
Retrofit modern authentication (OAuth2, SSO), encryption, and API security to legacy systems.
API Layer Development
Add modern REST/GraphQL API layers to legacy systems, enabling integration without full replacement.
Code Refactoring & Documentation
Simplify complex codebases, add test coverage, and document undocumented systems for long-term maintainability.
Use Cases in Production
Real deployment patterns — the specifics vary per client, but the structure stays the same.
Financial ServicesCOBOL to Modern Platform Migration
A financial services company was running core calculations on a COBOL system that only two retiring developers understood. The system produced the right numbers but could not be integrated with modern reporting tools, and the succession risk was existential.
A phased replacement over 16 months: document the COBOL logic fully, build the replacement in Python with identical calculation outputs, run both systems in parallel for 6 months validating output parity on 100% of transactions, then decommission the COBOL system.
- 100% calculation output parity validated across 18 million transactions during parallel run
- COBOL system decommissioned with no business disruption
- New system integrated with 4 downstream reporting tools on day one of go-live
HealthcareWindows Desktop App to Cloud Migration
A healthcare software company had a 15-year-old Windows desktop application managing patient records for 80 GP practices. The application required on-site server infrastructure, was not accessible remotely, and could not meet modern NHS data security requirements.
Cloud migration to a web-based platform: core clinical features extracted and rebuilt as a React.js application with a Node.js API and PostgreSQL database hosted on NHS-accredited cloud infrastructure. Data migrated per practice with a 4-hour cutover window per site.
- All 80 practices migrated over 6 months with no practice data loss
- On-site server infrastructure eliminated — annual maintenance cost down £380K
- Remote access enabled for the first time — GPs can access records from any location
RetailERP-Adjacent Legacy System Decommission
A retailer's new ERP implementation left 3 legacy systems still running because the ERP did not fully cover their requirements on day one. 4 years later, the legacy systems were still running alongside the ERP — creating duplicate data entry and regular reconciliation failures.
A systematic decommission programme: gap analysis between ERP capability and legacy system functionality, custom development of 6 missing ERP features, data migration from each legacy system, and a structured cutover sequence that retired all 3 legacy systems over 9 months.
- All 3 legacy systems decommissioned within 9 months
- Duplicate data entry eliminated — estimated saving of 1,200 staff hours per year
- Data reconciliation failures eliminated from day one of each legacy system retirement
Why Choose Us for Legacy Software Modernisation
Security Remediation
Resolve authentication vulnerabilities, unpatched dependencies, and compliance gaps in your legacy system.
Performance That Scales
Modern cloud-native infrastructure delivers the performance and reliability your legacy system never could.
Zero Disruption Approach
Strangler fig and parallel running patterns keep your business operating throughout the entire transition.
Technical Debt Eliminated
Clean, documented, well-tested codebase that your team can maintain and extend without archaeology sessions.
Our Delivery Process
A structured path from business process discovery through to live deployment and continuous improvement.
Assessment & Discovery
Architecture review, dependency mapping, security audit, and modernisation priority scoring.
Strategy & Roadmap
Define modernisation approach, technology choices, phasing plan, and risk mitigation measures.
Incremental Modernisation
Component-by-component transformation with parallel running and continuous validation.
Cutover & Optimise
Final cutover with rollback plan, performance benchmarking, and post-transition monitoring.
Industries We Serve
Technologies We Use
Industry-proven tools chosen for performance, reliability, and long-term support.
React
Node.js
AWS
DockerFrequently Asked Questions
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