Senior software engineer building backend APIs, event-driven services, and SQL-based data integrations. Delivered trading workflows at Invnex and banking-data reconciliation at Actus. Current independent work uses Rust for transaction processing and recovery, Python for operational automation, and ClickHouse for analytics.
Built Go services with PostgreSQL and AWS for account management, trading, and related compliance workflows on a live tokenized-asset platform that reached its initial customers.
Implemented REST APIs and integrated Ethereum smart contracts through on-chain event indexing and transaction submission.
02
Experience
Backend, platform, and product work across financial services and enterprise software.
Built Go, Java, Node.js, and Python services to transform banking data for accounting workflows.
Used SQL to reconcile duplicate financial transactions, validate totals by account and currency, and flag ambiguous matches while retaining an audit trail.
Designed APIs and background jobs with retries and idempotency keys.
Automated cloud deployments with Terraform and CI/CD; added monitoring dashboards and alerts.
Developed an MVC web app to monitor ambulance fleets (.NET, JavaScript, MS SQL) with real‑time GPS tracking.
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Systems & skills
Languages, infrastructure, and the engineering practices behind the work.
Backend languages & APIs
Rust / Python, current independent work
Go
Java / Spring
C# / .NET
Node.js / TypeScript
REST APIs
Data & integration
SQL / PostgreSQL / MS SQL
ClickHouse, independent project
Kafka
Idempotency / retries
Cloud & delivery
AWS
Docker / Kubernetes
Helm / Flux
Terraform / CI/CD
Prometheus / Grafana / OpenTelemetry
04
Colleague feedback
Careful judgment with financial data
Actus AG · Senior Software Engineer Go · Java · SQL
Guillem brought careful judgment to the banking-data services at Actus. With duplicate transactions, he looked beyond records that appeared similar and checked whether they were genuinely repeated. He validated totals by account and currency, preserved an audit trail, and left uncertain matches for review. That care mattered: correcting one problem should not create another.
Philipp Wirtenberger, Head of Engineering at Actus AG
Guillem understood the work beyond writing application code. At HelloFresh, he built customer and platform services in C#/.NET and worked with PostgreSQL and Kafka for event integrations. He also helped operate services through Kubernetes, Helm, and Flux, and contributed to Terraform and CI/CD. His contribution connected the application with how it was packaged, deployed, and run.
Bruno Karin, Senior Platform Engineer at HelloFresh
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Education & languages
Universidad Autónoma de Barcelona (Autonomous University of Barcelona) Bachelor's degree in Telecommunications and Software Engineering 2012 – 2016
Languages
Spanish · Native Catalan · Native English · Native
Contact
Have a backend role in mind?
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