Running a business-critical system on software the original vendor stopped supporting -- one server failure away from losing years of operational data?
Paying developers to maintain a legacy codebase that takes longer to understand than to rewrite, while new features are impossible to add without breaking something?
Legacy Software Modernisation
Replace or incrementally migrate aging systems -- monolithic codebases, end-of-life frameworks, on-prem infrastructure -- without losing business logic or causing operational disruption. Planned modernisation at a pace the business controls, not a crisis response to a system failure.
We audit the existing system before writing a line of code, plan the data migration before cutover, and replace only what needs replacing. Fixed cost agreed before development starts.
Full code and data audit before a line is written
Data migration planned and tested before cutover -- no surprises on go-live day
Replace only what needs replacing -- not a forced rewrite of working components
Fixed cost, no discovering problems mid-project
RaftLabs replaces and modernises legacy software systems -- monolithic codebases, end-of-life frameworks, and on-prem infrastructure -- with modern architecture that reduces maintenance cost and operational risk. We audit the existing system first, plan migration before cutover, and use incremental approaches like the strangler fig pattern to avoid big-bang rewrites.
Legacy systems don't fail on a schedule. They fail when the server hardware dies, when the operating system reaches end of support, or when the one person who understood the codebase leaves. The risk of running on a legacy system compounds quietly until a single event turns it into an emergency.
Modernisation is not a rewrite for its own sake. It is the planned replacement of a system that carries operational risk -- done at a time and pace that the business controls, using an approach that preserves the business logic that took years to build.
What we do
Monolith-to-microservices migration
Incremental decomposition of monolithic applications into independently deployable services -- without a big-bang rewrite that stops the business while the new system is built. Domain boundary identification, service extraction in order of business priority, and the API contracts that let old and new components coexist during the migration. The strangler fig approach applied to production systems that can't be taken offline for a rewrite. Each migrated service is deployed and validated before the next is touched.
Framework and language migration
Migration from end-of-life frameworks and languages -- PHP 5, AngularJS, Classic ASP, .NET Framework, Ruby on Rails legacy versions -- to supported modern equivalents. Codebase audit to identify the scope of migration, feature-by-feature conversion with test coverage applied as work progresses, and a validation process that confirms the modernised application matches the behaviour of the original. The migration that keeps business logic intact while removing the technical debt that makes the system expensive to maintain.
Database modernisation
Migration from legacy database technologies -- on-premises SQL Server, Access databases, Oracle instances, and proprietary database formats -- to modern managed database infrastructure. Schema redesign where the legacy model reflects constraints of the original platform rather than the business data model. Query optimisation and index strategy for the new system. Migration scripts tested repeatedly against a copy of production data before the live cutover. The database migration that improves performance and reduces infrastructure cost without losing years of operational data.
API wrapper strategy
Where a full replacement isn't feasible in a single engagement, an API wrapper isolates the legacy system behind a clean interface so modern applications can consume its data and capabilities without direct integration to the aging internals. The wrapper becomes the migration boundary -- new features are built against the clean API, and the legacy internals are replaced incrementally without changing the consuming applications. The approach that reduces the blast radius of modernisation to one system at a time.
Cloud migration for legacy apps
Lift-and-shift migration of on-premises applications to cloud infrastructure, followed by modernisation of the components that prevent cloud-native operation -- manual deployments, hardcoded server paths, on-prem database connections, and the configuration that assumes physical hardware. Infrastructure-as-code setup, automated deployment pipelines, and the monitoring stack that gives your team visibility into a cloud-hosted system. The migration from on-prem operational risk to managed cloud infrastructure with automated backups and scaling.
Legacy codebase documentation and audit
Structured audit of a legacy codebase with no documentation -- identifying what the code actually does, mapping the data model, documenting the business rules embedded in application logic, and producing a dependency map that shows what connects to what. The output is an assessment report that gives your team the information needed to make a modernisation decision: what the system does, what it costs to maintain, what the risks are, and what a replacement would require. The foundation for a modernisation plan rather than a blind rewrite.
Have a legacy system that needs replacing?
Tell us what the system does, how long it's been running, and what's driving the need to modernise. We'll audit it and give you a fixed cost.
Related custom software services
Custom Software Development -- full custom software capability overview
Web Application Development -- the modern replacement for legacy desktop and web systems
Enterprise Software Development -- for organisations replacing complex enterprise platforms
MVP Development -- validate the replacement before committing to the full build
Related services
Cloud Migration -- moving legacy infrastructure to cloud
DevOps -- CI/CD pipelines for modernised applications
Frequently asked questions
The right time is before a failure forces the decision. Indicators that modernisation is overdue include: the vendor no longer releasing security patches; the system runs on hardware that can't be replaced like-for-like; the team maintaining it is shrinking and the knowledge is leaving with them; new features take months because every change risks breaking something else; or the system can't integrate with tools the business now depends on. When any of these apply, the risk of staying on the legacy system is compounding. Modernisation planned on your schedule is materially cheaper than emergency recovery after a failure.
Cutover strategy is designed during the assessment phase, before development begins. For most systems we use a parallel running approach -- both old and new systems operate simultaneously while the new system is validated against real data. Cutover happens in a planned window, typically outside business hours, with a tested rollback plan. For systems where parallel running isn't feasible, we use a phased cutover, moving one function or department at a time to reduce the risk of a single large transition. The business never faces a situation where the old system is decommissioned before the new one is verified.
The strangler fig pattern is an approach to legacy migration where you incrementally replace pieces of the old system with new components, rather than doing a big-bang rewrite. New functionality is built in the modern system; existing functionality is migrated piece by piece over time. The legacy system handles less and less over the migration period until it can be decommissioned entirely. This approach keeps the business running throughout the migration, reduces the risk of any single large transition failing, and lets the team validate each migrated component before moving to the next. It takes longer than a rewrite but carries significantly less operational risk.
Replacing a focused legacy system -- a single application, clear scope, and manageable data migration -- typically runs $30,000 to $80,000. Modernising a large legacy platform with multiple integrated modules, complex data migration, and a phased cutover strategy typically runs $80,000 to $200,000+. Fixed cost agreed before development starts. The assessment engagement that precedes the development quote is what makes that fixed price possible -- we price based on what we find, not what we assume.