Retire the Legacy Without Dropping a Single Transaction
Application and platform modernization — strangler-fig migrations, mainframe retirement, and cloud-native rebuilds that de-risk delivery by never betting everything on one cutover.
Why Platform Modernization Programs Stall
The legacy platform still works — that's the trap. Every year it runs, the modernization gets harder: the engineers who understand it retire, the integration workarounds multiply, and the business builds new processes on assumptions only the old system honors. By the time a mandate forces the issue, 'rewrite it' and 'keep patching' are both unaffordable.
The Apptad Approach to Platform Modernization
We modernize incrementally behind stable interfaces — the strangler-fig pattern: a new experience layer in front, services cut over one by one behind the same APIs, and the legacy core retired only when nothing calls it anymore. Risk stays bounded per slice; the business never takes a big-bang weekend.
Strangler-fig, not big bang
Service-by-service cutover behind stable APIs. Our state-agency program retired a 22-year-old mainframe over 26 months without one dropped citizen interaction.
Experience first
A modern front door (portal, APIs) ships early value while the core migrates behind it — stakeholders see progress in months, not years.
Knowledge capture before it retires
Legacy behavior documented as executable tests — the retiring system becomes the spec for its replacement.
Cloud-native, compliance-ready
Cloud Run / Kubernetes microservices, IaC, and the compliance posture (StateRAMP, FedRAMP-aligned) regulated and public-sector estates need.
Platform Modernization in Production
State Agency Modernizes Citizen Services on Google Cloud
Replaced a 22-year-old mainframe permitting system with a cloud-native citizen portal — application processing time dropped from 21 days to 4.
Read the case study
Regional Health System Cuts Infrastructure Costs by 42% on AWS
A 12-hospital health system migrated 380+ workloads to AWS GovCloud with a HIPAA-compliant data lake — slashing spend while improving reliability.
Read the case studyPlatform Modernization, Answered Straight
Rewrite, replatform, or replace with SaaS?
Per capability, not per system. Commodity functions go to SaaS; differentiating logic gets rebuilt cloud-native; stable-and-cheap can replatform or stay. The mistake is answering once for a whole estate — a portfolio assessment that scores each capability on differentiation and change-rate gives you the honest map.
How do you de-risk a mainframe retirement?
Never bet the program on one cutover. Strangler-fig sequencing puts new services behind the same interfaces, runs old and new in parallel per slice, and keeps a rollback path until each slice proves out. Our 26-month state-agency retirement dropped zero interactions because no single step was irreversible.
What happens when only three people understand the legacy code?
That's a countdown, and it's the real budget argument. First move: capture behavior as executable characterization tests while those engineers are still in the building — the legacy system becomes its own spec, and modernization stops depending on memory.
Part of our Enterprise Solutions practice.
Have a Platform Modernization Question? Ask the People Who Ship It
Our Enterprise Solutions practice is led hands-on. Connect on LinkedIn or send a note through the form — a practitioner (not a sales rep) replies within one business day.
