Legacy Modernisation
Escape the legacy trap without disrupting the business that runs on it.
Outdated systems don't just slow development — they accumulate risk. We modernise legacy applications through API wrapping, incremental re-platforming, database migration, and zero-downtime cutover strategies that let you move to modern architecture without betting the business on a big-bang rewrite.
What you get
What's included in our
Legacy Modernisation engagement
Strangler Fig Migration — No Big Bang Rewrites
We apply the strangler fig pattern, incrementally replacing legacy functionality with modern services while the old system keeps running. Each piece is migrated, tested, and de-risked independently — so the business never faces a go/no-go cliff edge.
API Layer Over Existing Systems
Where a full rebuild is premature, we wrap your existing legacy application in a clean REST or GraphQL API. This isolates the old system, allows new frontends and integrations to be built immediately, and creates a migration path that proceeds at your pace.
Zero-Downtime Database Migration
Database migrations are the most risk-laden part of any modernisation. We use dual-write strategies, shadow reads, and incremental cut-over techniques that allow your production database to be migrated to a modern platform without a maintenance window.
Our process
How we deliver Legacy Modernisation
Legacy System Assessment and Risk Mapping
We conduct a thorough technical audit of your existing system — documenting architecture, data flows, integration points, undocumented business logic, and areas of highest technical risk. You receive a frank assessment of what can be migrated, what should be rebuilt, and what can be retired.
Migration Roadmap and Pattern Selection
Based on the audit, we define the migration strategy: strangler fig, API wrapper, database-first, or phased rebuild. The roadmap sequencing priorities minimise business disruption while progressively de-risking the legacy dependency — each phase delivers standalone value.
Incremental Migration with Parallel Running
Each migration phase runs the legacy system and the new system in parallel, with dual-write synchronisation where needed. Cutover decisions are made by you, based on observed data consistency and user confidence — never forced by a project deadline.
Legacy Retirement and Final Cutover
Once all functionality is migrated and validated, we execute the final legacy shutdown with a tested rollback plan standing by. We decommission infrastructure, archive data per your retention policy, and document the complete new architecture for your team.
Stack
Technologies we use
Why Palsoro for Legacy Modernisation
We've Read the COBOL So You Don't Have To
Our team has reverse-engineered mainframe applications, undocumented VBA macros, and decade-old PHP monoliths. We identify hidden business logic buried in legacy code before it becomes a production incident in your new system.
Risk-First Planning
Every legacy modernisation carries risk — the question is whether it's managed risk or surprise risk. We front-load the hard decisions, build rollback capability into every migration step, and never recommend a cutover until the evidence says it's safe.
No Disruption to Day-to-Day Operations
We schedule migration phases around your business calendar, avoid peak periods, and design every step to be reversible. The people running your business on the legacy system should feel minimal disruption during the modernisation process.
Timelines vary significantly by system complexity. API wrapping a single legacy system can take 8–12 weeks. Full re-platforming of a complex enterprise application typically spans 6–18 months, delivered in phases with value at each stage rather than a single end-of-project delivery.
Yes. Cloud migration is often a component of modernisation engagements. We handle lift-and-shift migrations as a starting point where appropriate, followed by cloud-native re-architecture. We work across AWS, Azure, and GCP depending on your organisational preference and existing vendor relationships.
We treat undocumented logic discovery as a critical project phase. We run the legacy and new systems in parallel with data comparison to surface discrepancies, and we interview the business users who know the legacy system's quirks before anyone retires from the company.
In some cases, yes. Where source code is unavailable, we work from binary analysis, API observation, database schema inspection, and business process documentation to reconstruct the functional specification. It adds time and cost, but it's achievable for many common legacy platforms.