Gonzalo Martin PerezAI Software Engineer

Stack

What I work with, and where I used it

Grouped by what it is for rather than by language, and each group names where I used it. A list of technologies without that context is just a list.

Applied AI & agentic systems

An in-product RAG assistant for merchant owners at Payway scale, MCP and LLM pipelines for independent clients, and agentic engineering workspaces at Rampy, Teamcubation and Cooperativa Obrera.

  • AI agents
  • RAG
  • LangChain
  • LangGraph
  • Model Context Protocol
  • LLM integration
  • Vector databases
  • pgvector
  • Guardrails
  • Claude API
  • Spec-driven development

Backend & APIs

Microservices and BFFs in production at Payway and Cooperativa Obrera, and the REST API behind Filomena.

  • Spring Boot
  • FastAPI
  • NestJS
  • Spring WebFlux
  • Spring MVC
  • Spring Security
  • Spring Data JPA
  • Laravel
  • REST APIs
  • Microservices
  • API design

Languages & runtimes

Used across every role listed on this site.

  • Python
  • TypeScript
  • Java
  • JavaScript
  • Node.js
  • SQL
  • PHP

Frontend & product interfaces

A microfrontend embedded in the Payway merchant portal, the SGA back office, and the Filomena application.

  • React
  • Next.js
  • Single-SPA
  • Microfrontends
  • Responsive design
  • WordPress

Data & architecture

Event-driven ingestion at fintech scale, hexagonal and layered services, and query tuning on exam and permission paths.

  • PostgreSQL
  • MySQL
  • Redis
  • System design
  • Distributed systems
  • Hexagonal architecture
  • Layered architecture
  • Event-driven architecture
  • SQL tuning
  • Indexing
  • Caching
  • Data modelling

Cloud & delivery

Application development on AWS managed services, and containerised workloads I built, configured and diagnosed as a developer — not cluster administration or infrastructure ownership.

  • AWS Lambda
  • Amazon API Gateway
  • Amazon S3
  • Amazon SQS
  • Amazon CloudWatch
  • Serverless
  • Docker
  • Kubernetes
  • GitLab CI/CD
  • GitHub Actions
  • Git
  • Linux

Quality, observability & security

Monitoring and access control in production on SGA and Filomena, and test tooling across JVM and JavaScript services.

  • JUnit
  • Mockito
  • Jest
  • React Testing Library
  • Testcontainers
  • SonarQube
  • OpenTelemetry
  • Prometheus
  • Grafana
  • Structured logging
  • RBAC
  • LDAP
  • Application security

Delivery & collaboration

Agile practice in every role, with the tooling each organisation used.

  • Agile
  • Scrum
  • Kanban
  • Jira
  • Trello
  • Code review
  • Technical documentation

Fintech & blockchain

Production fintech experience at Payway, plus blockchain knowledge in consolidation. Listed as complementary knowledge, not as a primary specialisation.

  • Fintech
  • Blockchain
  • Web3
  • Account abstraction
  • Smart accounts
  • DeFi
  • ERC-20
  • ERC-4337

A note on how this list is written

Cloud and container entries describe application development: building services, integrating managed services, configuring and diagnosing workloads. They do not claim cluster administration, infrastructure provisioning or platform ownership, because that was not my role.

Names appear as text rather than as vendor logos. Redistributing third-party marks on a personal site is restricted by several of those vendors' own brand policies, and a logo would not tell you anything the name does not.