Senior Backend Engineer
Distributed systems that run in production

Javier Pontón González is a Senior Backend Engineer based in Asturias, Spain, working remotely on CET. He has eight years of production backend engineering for Iberia, Mercadona, Inditex, Openbank and Idealista: Java, Kotlin and Python services on Spring Boot and FastAPI, event-driven integration over Kafka and PostgreSQL, and AWS. He also runs LLM features such as RAG and MCP in production.

Since March 2025 he is a Senior Software Engineer at Iberia, remote from Spain, and technical owner of the fare pricing domain on the airline's flight pricing platform. The services orchestrate external fare-calculation providers under IATA NDC on Kafka, PostgreSQL and AWS (ECS, SQS, S3) in hexagonal architecture with DDD, with Redis caching on the busiest flows and timeouts, retries and fallbacks against provider degradation. On top of that he built an internal MCP server and a RAG service in Python and FastAPI over internal specs and NDC documentation. He is engaged B2B through his own company.

At Openbank he built serverless batch pipelines on AWS Lambda processing millions of financial transactions per day on the T24 core banking system, and led the Java to Kotlin migration inside an organisation of more than 100 backend engineers. At Mercadona he led a Spring Batch ingestion pipeline processing millions of product records per day with restartable jobs and idempotent writes, and sustained over 85% test coverage under TDD.

At Iberia the pricing path depends on external fare-calculation providers, so he owns its resilience: timeouts, retries and fallbacks against provider degradation, Redis caching on the highest-traffic flows to cut latency and provider calls, and OpenTelemetry and Dynatrace for visibility when something degrades.

Yes. He was technical lead of the zero-downtime Azure to AWS migration of a global logistics event platform at Inditex, which processes thousands of garment-sorting events per minute, and of the Java to Kotlin migration at Openbank inside an organisation of more than 100 backend engineers. At Empathy.co he executed zero-downtime migrations from Java 8 to 11, GCP to AWS and monolith to API Gateway.

He treats LLM features as normal backend services: RAG with embeddings, hybrid search and cross-encoder reranking, pgvector, MCP servers and function calling, with evaluation and OpenTelemetry tracing. At Iberia he built an internal MCP server exposing pricing tooling to LLM clients and a RAG service in Python and FastAPI over internal specs and NDC documentation, with source-grounded answers in under a minute. In his own products, Facturias retrieves over Spanish tax regulation and Grabia retrieves over a local meeting archive.

Four live products as founder and sole engineer. Facturias (facturias.es) is an invoice-processing SaaS with a self-hosted vision-language model and RAG over Spanish tax regulation. ZORRO (somoszorro.com) is a dating app for the gay and queer community on iOS and Android with semantic matchmaking and self-hosted photo moderation. Apunta (apuntapp.com) is a multi-tenant SaaS for shooting clubs owned end to end from custom NFC hardware to the mobile app. Grabia is a fully local meeting-intelligence pipeline running on a private inference node.

Java, Kotlin and Python on the language side, with Elixir and TypeScript where needed. Spring Boot and FastAPI for services. Apache Kafka for events. PostgreSQL with pgvector, Redis, MongoDB and Elasticsearch for data. AWS (ECS, Lambda, SQS, S3), Azure and GCP, with Docker and Kubernetes. Hexagonal architecture, DDD and TDD as the default way of building, and OpenTelemetry, Prometheus and Grafana for observability.

He is based in Asturias, Spain, in the Europe/Madrid time zone, and works remotely with teams across the EU, UK and US. He is a native Spanish speaker with professional working proficiency in English.