SEGUROS DE SALUD

How a major health insurer migrated 1,200 VB6 screens
without interrupting service

A critical healthcare management system, with more than 1,200 screens developed in Visual Basic 6, thousands of active daily users, and more than 5 million insured members managed. This was the scenario faced by one of Spain’s leading private health insurers when it decided to undertake its modernization. The insurance legacy modernization success story documented in this project shows that full isofunctionality and operational continuity are not mutually exclusive goals: with the right process, they coexist.

Project scope


  • More than 1,200 functional screens and components modernized
  • More than 20 batch processes with approximately 800 jobs migrated
  • More than 5 million insured members managed by the organization
  • Integration with corporate tools: Excel, Word, PDF, and Crystal Reports
  • Cloud architecture designed for high concurrency and scalability

The starting point: a critical system that could not be stopped

The platform had been evolving continuously for years. What began as a VB6 application had become the operational core of an organization with millions of insured members.
Stopping the system during the migration was not an option: the business operates in real time, with authorization, appointment management, and coverage control processes that cannot tolerate interruptions.
The technical challenge was not only technological. It was to demonstrate that 1,200 screens, each with business logic accumulated over years, could be moved to a modern web architecture while preserving functional behavior identical to the original.
According to Gartner data (2023), 74% of manual legacy application modernization projects exceed their initial budget. The chosen alternative was an automatic migration process with isofunctional verification, eliminating dependency on human interpretation of business logic.

imagen de una aseguradora de salud

The solution: automatic migration to Spring Boot and Angular

Go4IT Solutions carried out the full modernization of the platform, evolving the solution from VB6 to a web architecture based on Spring Boot and Angular. The project covered the migration of 50 modules, more than 1,200 screens, and over 20 batch processes totaling approximately 800 jobs, as well as all existing integrations. The target architecture included a cloud deployment with load balancing designed to support the concurrency levels required by large-scale insurance operations. A critical aspect of the project was preserving integrations with corporate tools: Microsoft Excel, Word, PDF document generation, and reporting solutions based on Crystal Reports. These integrations were used daily by thousands of users, and their loss or degradation would have had an immediate operational impact.


Results: modern platform, continuous operations,
business logic intact

The result of the project was a fully modernized technology platform, with a scalable cloud architecture ready for future digital transformation initiatives, while fully preserving the original functional behavior. The isofunctional process ensured that none of the 1,200 screens lost functionality during the migration. The progressive modernization strategy allowed the business to continue evolving throughout the project, without freezing the source code or imposing downtime periods. For an organization with more than 5 million insured members and thousands of active daily users, operational continuity was not a secondary objective: it was the project’s main success criterion.

Key challenges addressed

  1. Ensure a fully isofunctional migration, preserving all the business logic accumulated over years.
  2. Maintain operational continuity throughout the entire process: the platform could not stop providing service at any point.
  3. Support the high levels of concurrency and availability required by large-scale insurance operations.
  4. Deploy the solution on a scalable cloud architecture with load balancing.
  5. Maintain integrations with productivity and reporting tools widely used by the teams.
Delivered by

Project team

Guillermo Rodríguez
Project Leader Guillermo Rodríguez

at GO4IT Solutions, a spin-off from Tecnalia, has supported modernization projects in the banking, insurance, and retail sectors in Spain and Europe, with clients operating critical systems with volumes ranging from 500 to 6,000 functional windows.

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