S Sergi Francés

Senior Backend Engineer

I build reliable backend systems for marketplace, financial, and data-intensive workflows.

PHP/Symfony engineer experienced in distributed systems, event-driven processing, analytical architectures, and database optimization—combining hands-on delivery with technical ownership.

View experience GitHub LinkedIn
  • PHP
  • Symfony
  • Kafka
  • Flink
  • Airbyte
  • ClickHouse
  • MySQL

About

Backend engineering from product requirements to reliable delivery.

I translate product requirements into technical designs and implementation plans, then contribute hands-on across APIs, data flows, integrations, testing, and delivery.

My experience spans marketplace operations, finance and ERP, analytical reporting, and distributed processing—systems where data quality, reliability, and operational visibility matter.

Experience

A technical path with growing responsibility and ownership.

Backend Software Engineer METRO Markets GmbH · May 2022 – Present

Marketplace / Seller Account & Offer Management

Building and maintaining backend capabilities for seller onboarding, account management, offer lifecycles, competitive pricing, and destination-specific marketplace behaviour.

  • Technical ownership from requirements and design through decomposition and hands-on delivery.
  • End-to-end market-price data flows across orchestration, ClickHouse, Kafka/Flink, Elasticsearch, and APIs.
  • Data-quality work covering GTIN relevance, duplicate handling, and downstream readiness.
  • Testing, E2E demos, observability, incident response, and cross-team coordination.
Backend Engineer SUSA / Reporting

Financial reporting modernization

Owned the technical implementation of moving analytical reporting workloads from MySQL to ClickHouse with Airbyte replication and materialized views.

  • Separated complex reporting workloads from the transactional database.
  • Implemented and validated reporting for sales, invoices, VAT, liabilities, and consolidated views.
  • Created Grafana dashboards and alerts, including Slack notifications routed through n8n.
Backend Engineer Admin & Finance / ERP

Finance / ERP / Admin & Finance

Built and maintained business-critical functionality for invoicing, credit notes, VAT and tax, payments, e-invoicing, and marketplace-to-finance data processing.

  • Migrated and extended finance integrations to the Amazon Selling Partner API.
  • Implemented external financial integrations and country-specific accounting requirements.
  • Improved reliability through error handling, retries, reprocessing, and automated tests.
Web Developer Conjurer Services / IKEA · Oct 2021 – Mar 2022

Production web platform maintenance and evolution

Delivered bug fixes and incremental features for IKEA web platforms across the Balearic Islands, Canary Islands, Baltic countries, and Iceland using PHP, jQuery, and SVN.

PHP / Symfony Developer Tiendeo · Jan 2021 – Aug 2021

Retail data extraction and automation

Developed PHP/Symfony crawlers for heterogeneous retail websites and automated scheduled data collection with Jenkins and cron across HTML, embedded JSON, and public API sources.

Stack & capabilities

Strong experience across backend, data, and distributed systems.

Backend

  • PHP
  • Symfony
  • REST APIs
  • API Design
  • MySQL
  • Redis

Streaming & analytics

  • Kafka
  • Flink
  • ClickHouse
  • Elasticsearch
  • Airbyte
  • Dagster

Infrastructure & delivery

  • Docker
  • Google Cloud
  • RabbitMQ
  • Grafana
  • CI/CD
  • GitHub Actions / Jenkins

Engineering focus

  • Technical ownership
  • Software architecture
  • System design
  • Testing & observability
  • Incident response
  • Cross-team coordination

Impact

Ownership across design, implementation, and operations.

Architecture

Turning product requirements and complex business rules into maintainable backend designs.

Data

Building event-driven pipelines and moving analytical workloads to scalable data architectures.

Delivery

Coordinating dependencies while supporting testing, CI/CD, observability, and incident response.

Selected work

Business problems translated into reliable backend and data solutions.

Market data integration & processing pipeline

Built an end-to-end flow that integrates externally collected pricing data through orchestration, analytical storage, event-driven processing, search indexing, and backend/API consumption.

Modernizing financial reporting

Moved analytical workloads from MySQL to ClickHouse with Airbyte replication and materialized views, reducing transactional database pressure and improving reporting scalability.

Cap'n Hook

A Symfony webhook reliability and observability service with durable ingestion, asynchronous RabbitMQ delivery, retry and dead-letter handling, inspection, and replay capabilities.

View repository

Contact

Let’s talk about backend systems, architecture, and data-intensive platforms.

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