Engineering
Modernize the legacy system without stopping the business.
Assessment, incremental migrations, re-platforming, database modernization and cloud native refactoring, in steps that each deliver value.
Sound familiar
Where this usually starts.
Legacy systems are usually legacy because they work and the business depends on them, and rewriting them in one project is the riskiest way to replace them. We modernize in increments: put a stable interface in front of the old system, move capabilities one at a time to new services behind it, migrate data alongside, and retire the old parts as they empty. Each step delivers something useful and can be reversed.
Scope
What is included.
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Portfolio assessment
Each application assessed to retain, rehost, replatform, refactor, replace or retire.
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Incremental migration
New services built around the old system, with traffic moved over gradually.
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Re-platforming
Applications moved to supported runtimes, containers or managed services.
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Database modernization
Data moved off legacy databases with validation and reconciliation.
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Coexistence
Interfaces that let old and new systems run side by side during the transition.
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Retirement
Old components decommissioned once their last user has moved.
Reference architecture
From commit to production, and back again when it breaks.
Modernization works on the production side of the engineering architecture: it puts a stable interface in front of the legacy system and moves capabilities to new production services one at a time.
What this service delivers here
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Production services
The running system, deployed the same way every time.
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Legacy system
Still running, and being replaced one capability at a time.
Before you start
Decisions to settle early.
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Modernize or replace
A commodity capability is often better replaced by a product; a differentiating one is worth modernizing. The call is made per capability.
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Which capability first
Starting with something valuable and separable proves the approach. The seams in the system decide.
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How long old and new coexist
Coexistence costs money but removes risk. The roadmap sets an end date for each part of the old system.
Approach
How the work runs.
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Assess
Code, data and dependencies
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Wrap
A stable interface in front
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Replace
Capabilities moved one at a time
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Retire
Old parts decommissioned
Commercials
How it is bought.
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A fixed-fee assessment
We read the code, data and interfaces of the system and find the seams where it can be divided. You receive the assessment, a roadmap outline and a fixed price for the first increments.
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A fixed-price build
Each increment, wrapping, replacing a capability, migrating its data and retiring the old part, is priced before it starts.
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Running it afterwards
Between increments, the coexisting systems can be operated by your team or by us, and the roadmap is reviewed as each step lands.
Start with the assessment.
Worked example
A core system nobody wants to touch.
Say an insurer's policy administration system runs on an old platform that few engineers still know. Every change takes weeks, a full rewrite was abandoned once, and its hosting cannot follow the rest of the estate into the cloud.
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Assess
We read the code, data and interfaces, map which capabilities matter most, and find the seams along which the system can be divided.
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Wrap
A stable API is placed in front of the old system, so other applications stop depending on its internals.
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Replace
Quoting moves first to a new service behind the API, with traffic shifted gradually and the old path kept as a fallback.
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Retire
As each capability moves and its data is reconciled, the matching part of the old system is switched off.
At the end, each step has delivered something the business uses, the old system shrinks with every release, and no single cutover has put the business at risk.
An illustration
Where it goes wrong
What we design out.
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The big rewrite
Replacing a core system in one project is the riskiest way to do it. Capabilities move one at a time.
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Changing behavior by accident
Without tests, nobody knows what the old system really does. Characterization tests record it first.
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Data left for last
Moving code without its data leaves both systems half alive. Data moves with each capability.
Outcomes
What it changes.
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Value at every step
Each increment delivers a working improvement, not a promise at the end.
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Risk kept small
Changes are small and reversible, so a failure is a rollback rather than a crisis.
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A platform people can change
Modern services can be changed quickly by engineers you are able to hire.
How you will know it is working
- Every increment delivers something the business uses.
- The legacy system shrinks with each release.
- Each step can be reversed.
- Changes take days instead of weeks as more capability moves.
You keep
What you have at the end.
Handover pack
five items
- Application assessment and modernization roadmap The condition of each application and the path chosen for it, in a sequenced plan.
- Target architecture The design the system is moving towards, and how old and new parts coexist on the way.
- Incremental migration plan The order in which capabilities leave the old system, each step usable and reversible.
- Data migration and reconciliation reports Each data move validated against the source, with discrepancies resolved and recorded.
- Decommissioning records Evidence that each retired component was switched off, archived and removed safely.
The team
Who you work with.
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Modernization architect
Assesses the system, finds its seams and designs the target architecture.
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Software engineers
Build new services, characterization tests and the coexistence layer.
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Data engineer
Migrates and reconciles data as each capability moves.
What we need from you
- Access to the source code, databases and environments.
- People who know how the system is used, and its quirks.
- Business owners for each capability.
- Tolerance for change windows during migration.
Shipped with the pipelines, dashboards and runbooks to run it.
Questions
Questions we get asked.
Why not rewrite the system from scratch?
Because a big rewrite has to match years of behavior before it delivers anything, and many fail before they do. Incremental modernization delivers value early and keeps the option to stop at any point.
How do you understand an undocumented legacy system?
By reading the code, tracing the data and watching the system in production, and by talking to the people who use it. The findings become the documentation the system never had.
Can the old and new systems run side by side?
Yes, that is the point of the approach. An interface routes each request to whichever system currently owns that capability, and data is synchronized until the old system is retired.
How is a modernization program priced?
One increment at a time. The first is chosen to be small enough to reach production quickly, and each one after it is planned and priced on its own, so you can stop when the value runs out.
What is the strangler fig pattern?
A way of replacing a system gradually: new services are built around the old one behind a common interface and take over its capabilities one at a time, until the old system can be switched off. It is named after a plant that grows around a tree and eventually replaces it.
Should we replace a legacy system with a packaged product instead?
Sometimes. If the system does what many products already do, such as accounting or HR, a package is often the better answer. If it embodies how your business competes, modernizing it usually keeps more value. The assessment makes that call for each capability, not for the system as a whole.
How do you modernize a system that has no tests?
By writing characterization tests first, which record how the system behaves today, quirks included, before anything is changed. They become the safety net that shows whether a new service behaves the same as the part it replaces.
What happens to the data in the old system?
It moves with the capabilities that own it, and is validated and reconciled against the source at each step. History that no longer needs to be live can be archived in a form that stays queryable for audit and legal purposes.
Ask about your situation
Answered from this site, with its sources.
Where it is bought
Application modernization, by sector and region.
Sectors that buy Engineering
Often paired with
What usually comes next.
- Engineering
Software and product engineering
Products and platforms built for production from the first commit. - Cloud
Cloud strategy and migration
Landing zones and migrations sequenced around what cannot pause. - Integration
Application and API integration
APIs, events and middleware that connect the systems you run.
CONTACT
Replace the legacy system one piece at a time.
Share the system and what holds it back. We will propose the first increment and what it would deliver.
- Senior-led
- Accountable
- Direct
- Fixed-price options
- Compliance-ready
- 24/7 capable
Prefer to talk it through? Call +92 (333) 32 11011
What happens next
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You pick the time
Tell us what the system does and what it runs on; we arrange the call around you.
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Thirty minutes, with an engineer
A modernization lead discusses where the system can be divided and what to move first.
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A written assessment
You receive a written assessment and a fixed price for the first increments.