Alberto G.

Owning Santander’s core eSIM backend platform, orchestrating provisioning and subscription lifecycle flows across banking systems and external telecom providers in a large-scale retail banking environment.

• Led end-to-end backend integration across telecom and banking domains, orchestrating complex multi-step provisioning flows including eligibility validation, subscription lifecycle management, and cross-provider coordination.

• Led the design and delivery of the core business layer end-to-end: eSIM listing, user profile and subscription retrieval, invoice service, top-up contracting and consumption, and customer segmentation logic, orchestrating multiple concurrent reactive calls to external provider Gigs via WebClient.

• Re-architected the system into a fully non-blocking model using Spring WebFlux, isolating blocking JPA operations and reducing end-to-end latency by ~80-90%, enabling real-time concurrent orchestration across multiple external providers.

• Reduced technical debt by an estimated ~40% by removing legacy patterns, enforcing non-blocking integration practices end-to-end, and significantly improving maintainability and production readiness.

• Designed and implemented business validation logic within the banking domain: ownership verification of contracted eSIMs per authenticated user, legal entity type and age-based customer segmentation, and customerId resolution from the session token against the Gigs external provider.

Owned backend architecture and core integrations for Mapfre's global digital signature platform, operating across multiple European countries on AWS.

• Owned backend architecture of a multi-country digital signature platform across 5+ regulated European environments, designed to scale to 20+ countries, acting as the sole technical reference for all core integrations, architecture decisions, delivery, and production stability.

• Architected a dynamic document repository abstraction using Factory Pattern, resolving the correct backend (Documentum or DocThor) at runtime based on country, document type, and channel, fully decoupling the signature flow from any specific document system and reducing proprietary licensing costs.

• Led the critical end-to-end integration of DocThor as the new multi-country document repository for the platform: designed the integration architecture, implemented dynamic series and document type resolution, managed credential isolation per country via Secrets Manager, and certified the integration across all regulated environments.

• Architected and implemented multi-country access controls using Azure Entra ID OAuth2 tokens with country-based claims and backend ACL filtering, enforcing strict entity-level data isolation across all environments.

• Led Kafka-based event-driven integrations for document lifecycle management across multiple countries, processing hundreds of daily events with full audit traceability and a clear scaling path to thousands.

• Drove architectural trade-off analysis between DynamoDB Streams with OpenSearch and Aurora PostgreSQL, producing effort estimates and cost projections that directly informed the platform roadmap.

• Achieved an estimated 20-30% reduction in infrastructure costs and ~40% decrease in manual deployment effort through AWS CDK automation and GitHub Actions pipelines across DEV, PRE, and PRO.

Contributed to backend services supporting catalog, benefits, and transaction-processing capabilities within the TravelClub platform, later integrated into the Repsol Waylet ecosystem used by over 10 million users.

• Designed and evolved Java 21 / Spring Boot services within a hexagonal architecture, enforcing SOLID principles and clear separation between domain, application and infrastructure layers.

• Implemented multiple Amazon SQS consumers to process affiliate transaction events (Samsung, Awin, TradeDoubler, Commission Junction), including idempotent message handling, validation and transactional persistence.

• Built event ingestion pipelines validating third-party payloads using JSON Schema and transforming complex nested transaction data through MapStruct-based DTO mapping.

• Implemented serverless integrations using AWS Lambda and exposed REST APIs through AWS API Gateway, operating services via AWS-native CI/CD pipelines (CodePipeline, CloudFormation).

• Implemented multi-tenant configuration and dynamic datasource resolution using AWS Parameter Store, enabling per-account isolation without hardcoded infrastructure settings.

• Evaluated database options for specific use cases, comparing Aurora Serverless vs. RDS/PostgreSQL to optimize for cost, scalability, and operational overhead in a serverless-oriented architecture.