Legacy System Modernization Case Study
We upgraded legacy citizen-facing and back-office systems to modern cloud-based platforms without disrupting service delivery.
A two-decade-old Stack Holding Back Service Delivery for Millions
With our legacy system modernization capability services, we helped the agency modernize its citizen portals, permitting workflows, and internal case management without disrupting essential public services. Outages were frequent, deployments took weeks, and onboarding new services was nearly impossible before the transformation.
Aging Infrastructure
They were relying on old mainframes and on-prem servers that were outdated operating systems and were costing them $5.6M per year.
Fragile Integrations
Their 38 internal systems were connected with fragile point-to-point links. Many overnight batch jobs failed and needed manual fixing.
Poor Citizen Experience
Public portals were built on a legacy framework, but the pages were loading slowly (9.2 seconds). They had no mobile support, and their 38% of users abandoned forms before completing.
Compliance Pressure
In audit reports, we found issues such as unsupported components, missing disaster recovery, and failures to meet accessibility and data residency requirements.
Talent Risk
Their three employees understood the old COBOL and Oracle Forms systems, and they were close to retirement.
Zero Downtime Mandate
Services such as healthcare, unemployment support, and permits had to remain operational during system updates and migrations.
A Phased Replatforming Program
At Kerndev, we used the strangler fig approach to move features away from the old system without shutting down public services. Every step we delivered added useful improvements to move features away from the old system without shutting down public services. Every step we delivered added useful improvements.
Discovery and Domain Mapping
We identified 240 business capabilities, mapped how we will move data across 38 systems, and prioritized workloads based on risk, impact on citizens, and operating cost.
- Architecture and code review
- Capability dependency graph
- Migration risk scoring
- Cloud target architecture
Cloud Foundation
From the start, our experts implemented a secure multi-account AWS landing zone by using infrastructure as code, applied FedRAMP-aligned security controls, and built a unified monitoring system.
- Terraform landing zone
- Identity, logging, and policy guardrails
- CI and CD pipelines
- Centralized observability
API Gateway Migration
Placed a new API gateway and rebuilt every capability as container-based services, so the traffic is smoothly redirected, and users don’t notice any change.
- API gateway and routing layer
- Domain services in Node and Go
- Event driven data sync
- Progressive traffic cutover
Citizen Experience
We redesigned the public portal into a mobile-friendly React application that uses the new backend services and reduces friction.
- WCAG 2.2 AA accessibility
- Sub second page loads
- Self service status tracking
- Unified citizen identity
Decommissioning Old System
After all capabilities were migrated and tested, we turned off the old component, handed ownership to internal teams, and trained them according to the new platform.
- Legacy decommission plan
- Runbooks and SRE handover
- Internal platform training
- Continuous improvement model
Built for the Long Term with Cloud-Native Open Standards
Every component was chosen for portability, talent availability, and operational maturity in regulated environments.
Cloud and infra
- AWS GovCloud
- Terraform
- EKS Kubernetes
- CloudFront and WAF
Services
- Node.js and TypeScript
- Go for high throughput
- gRPC and REST APIs
- Event driven with Kafka
Data
- Postgres on Aurora
- Redis caching layer
- S3 data lake
- Debezium change capture
Experience
- React and Next.js
- Design system in Figma
- OAuth and SSO
- Analytics and feedback loop
Security
- Zero trust networking
- Secrets in AWS KMS
- SAST and SCA pipelines
- NIST 800-53 controls
Observability
- OpenTelemetry tracing
- Prometheus and Grafana
- Centralized logs
- SLO based alerting
Delivery
- GitHub Actions CI
- Argo CD GitOps
- Trunk based development
- Feature flags
Quality
- Playwright end to end
- Contract testing
- Chaos drills
- Accessibility automation
A Modern Platform That Delivers Value and Predicts What’s Next
Beyond the numbers
The agency ships new citizen services in weeks instead of quarters. Internal teams own the platform end to end, with runbooks and modern tooling. The public sees a portal that is fast, accessible, and works on any device. The technology is invisible, which is what good public infrastructure should be.
Kerndev replatformed the systems that touch every resident in our jurisdiction without a single hour of service downtime. The new stack costs us a fraction of what we used to spend and lets our team finally focus on serving people instead of fighting fires.Director of Digital Services / State Agency Client
Have a legacy system slowing you down?
Let us map a path off the legacy core and onto a stack your team will actually want to work on.