Legacy System Modernisation
Reduce Risk.
Improve Performance.
Keep the Lights On.
A controlled, staged approach to modernising legacy systems - designed to keep services stable, teams productive, and decision-making with you rather than the loudest new framework.
Get a Modernisation Plan Now
Stop Legacy Drag Before It Becomes a Major Incident
When critical services depend on systems that are hard to change, the business is already paying a hidden cost, releases feel risky, security work gets deferred, and teams spend time nursing unreliable integrations instead of delivering value. The cost rarely shows up as a single line item - it leaks out through outages, manual workarounds, duplicated data, vendor constraints, and the growing difficulty (and expense) of finding the right skills to keep ageing platforms alive.
Modernisation fixes this without betting everything on a full-scale rewrite. The path forward is staged and outcome-driven: stabilise what must stay up, then extend and evolve with bespoke integration layers, modern interfaces, and targeted upgrades that fit existing operations. With urgency and clear control points, it becomes possible to reduce risk quickly while building a platform that can actually change at the speed the business needs.
Here's what the modernisation programme delivers:
- Clear integration boundaries through APIs and event layers so systems exchange data reliably and reduce coupling
- Predictable change delivery via staged refactoring and modular upgrades that keep services stable
- Modern security controls (auth, access, encryption, auditability) aligned to today's compliance realities
- Improved reliability and observability so incidents are easier to prevent, diagnose, and resolve
- Reduced operational overhead by removing manual workarounds and fragile spreadsheet glue
- A bespoke roadmap shaped around constraints, dependencies, and the outcomes that matter most
If legacy risk is already slowing delivery or increasing exposure, the next step is to turn the unknowns into a plan with milestones you can execute. Get a Modernisation Plan Now
Platforms & Technologies We Work With
Non-exhaustive - depends on requirements.
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Integration & APIs
REST/JSON, API gateways, message queues, GraphQL/gRPC where appropriate
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Modernisation Approaches
Strangler pattern, refactoring, re-platforming, modular decomposition
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Data & Migration
ETL/ELT, CDC/event streaming, validation & reconciliation, data quality controls
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Security & Compliance
IAM/SSO, OAuth/OIDC, secrets management, audit logging
Use Cases to Cut Incident Risk and Restore Delivery Speed
Each use case is focused on reducing downtime risk, operational cost, and delivery friction while keeping services live.
Modernisation Outcomes You Can Measure
Modernisation should deliver measurable improvements without forcing risky, all-at-once change. We focus on stability first, then deliver upgrades that create flexibility and future readiness.
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Safer Modern Integration
Add API and middleware layers so legacy systems connect cleanly with modern applications and services. -
Improved Security Posture
Strengthen authentication, access control, encryption, and monitoring aligned to current best practice. -
Incremental, Low-Risk Delivery
Modular upgrades allow phased change, reducing downtime risk and avoiding single-step cutovers. -
Better Performance & Reliability
Reduce bottlenecks, stabilise dependencies, and improve resilience without replacing everything. -
Cleaner Operations
Lower maintenance overhead and reduce manual workarounds through automation and workflow improvements. -
Actionable Insights
Use analytics to make legacy data useful again - supporting reporting, forecasting, and operational visibility.
Built for the Industries That Cannot Stop
Legacy systems appear across every industry - often in the most critical operational areas. We modernise with the realities of uptime, regulation, and business continuity in mind, designing changes that are supportable and phased to reduce risk.
Telecoms
Improve service continuity and streamline operations while enabling newer platforms and data flows across sites.
E-Commerce
Reduce checkout friction, improve stability during peaks, and enable faster platform iteration without destabilising core services.
Healthcare
Strengthen security and compliance while improving interoperability across patient, clinical, and administrative systems.
Education
Improve reliability and performance for student and staff platforms while simplifying management and integration.
Logistics
Enable real-time visibility and workflow automation across fleet, warehouse, and dispatch systems.
Manufacturing
Stabilise production systems, enable predictive insights, and improve continuity across operational technology and enterprise platforms.
From Discovery to Delivery: How We Make Change Happen
We modernise in a way that protects uptime and gives you clear control over scope, risk, and sequencing. Every programme is built around your operational priorities, not a generic template.
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Landscape Discovery
We map your current environment in detail, including system boundaries, dependencies, data flows, and operational constraints. You get a clear view of where risk sits, what is costing time and money, and which improvements will unlock the most value first.
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Roadmap & Target Architecture
We design a staged plan with milestones you can validate, balancing quick wins with longer-term structural improvements. This includes technology choices, integration patterns, sequencing, and clear decision points so you stay in control as priorities evolve.
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Incremental Build, Integration & Modernisation
We implement integration layers, modern interfaces, and targeted component upgrades while keeping services stable. Each change is delivered in manageable steps, with testing, rollback considerations, and operational checks to minimise disruption.
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Handover, Enablement & Support Options
We provide practical documentation, knowledge transfer, and runbooks so your team can operate the modernised environment with confidence. If you want ongoing cover, we can continue through SLA-Based Technical Support or Dedicated Support Hours, tailored to the level of assurance you need.
Why Choose Onyxsis?
Proven Results in Complex Change
Outcomes over hype, with staged delivery and operational ownership kept clear.
In our Distributed Infrastructure Architecture case study, we helped a UK telecommunications provider shift from a fragile single hosting provider setup to a resilient, cloud-native architecture. The result: over 96% fewer unplanned outages and 24% lower annual hosting costs.
We achieved this by taking a staged approach, keeping operational ownership clear and focusing on outcomes rather than hype. You'll see the same discipline, transparency, and momentum applied to your modernisation journey from day one.
Open Source Values, Independent Thinking
We're genuinely passionate about open source, and we use it with intent to protect your options and reduce dependency on any single vendor. We'll challenge assumptions, explore unconventional solutions when they make sense, and design around what your business actually needs.
Senior Engineers, Personal Touch, Real Accountability
You get a small, committed team that stays close to your business, speaks plainly, and takes responsibility when challenges get difficult. We don't disappear behind layers of account management; the people doing the work are the people you can speak to.
Support That Doesn't Stop at Go-Live
After go-live, we stay involved to stabilise early-life usage, tune performance, and make sure your team is confident running what's changed. You'll have clear routes for escalation, practical help when the unexpected happens, and honest advice when trade-offs need to be made.
If you want longer-term cover, we can extend that partnership through SLA-Based Technical Support and Dedicated Support Hours. That gives you predictable access to engineers who already understand your environment, so improvements and fixes keep moving without friction.
If you want a modernisation partner who will take on the hard parts, keep you in control, and deliver measurable outcomes, let's talk through your constraints and priorities. We'll turn them into a staged plan you can trust, with clear milestones and no surprises.
Reduce Legacy Risk Before It Reduces You
Uncover where outages, security gaps, and hidden costs are brewing - and how to defuse them calmly.
