Acoru redefines fraud prevention by acting before the transaction is initiated!At Acoru, we stand at the forefront of fighting fraud, dedicated to protecting and serving with cutting-edge technology and smart solutions. Through continuous account analysis and classification, we identify risk using pre-fraud signals across all channels, before any transaction takes place. Our privacy-compliant intelligence network expands visibility beyond systems, empowering real-time, proactive defense.Launched in 2024, we are headquartered in Madrid with colleagues working throughout Europe, LATAM and the US. We have ambitious plans to double our headcount this year and again next year, as well as establish US and UK subsidiaries.OUR CULTURE We are passionate people who are eager to make a difference and ready to challenge the status quo by making the digital world a safer place.We attribute our success to the collaboration, creativity, and commitment of our team.We are remote-first with team members working around the world.We value effort, performance, and team work.We seek self-motivated individuals who own and execute their work. THE ROLEWe are seeking a Senior Backend Engineer to design, build and operate the high-performance, event-driven microservices that power our fraud and mule-detection platform. You'll work across our polyglot monorepo (orchestrated with Moon), building Nest JS services in Type Script, contributing to Java stream-processing and rules-engine components, and integrating with our Python AI/ML services, all deployed on Kubernetes. From high-throughput ingestion APIs to real-time risk evaluation, you'll directly shape the scalability, reliability and observability of our platform.WHAT YOU WILL DO Design, develop and maintain backend microservices in Type Script using Node.Js and Nest JS (CQRS, Fastify,



microservices patterns).Build and evolve customer-facing REST APIs and internal service contracts (Open API/Swagger, g RPC).Contribute to our event-driven architecture built on NATS / Jet Stream and Kafka, including messaging patterns, subject design and delivery guarantees. Data, Stream Processing & AI Integration Work on Java 21 components such as our Drools-based risk engine and Apache Flink stream-processing jobs.Model and optimize data access across Cassandra, Elasticsearch, Redis, My SQL and S3-compatible object storage (Min IO).Integrate backend services with our Python AI/ML layer (Fast API, Pydantic) for model inference and AI-assisted features.Instrument services with Open Telemetry (traces, metrics, structured logging) and help keep the platform observable and reliable.Ensure smooth deployments to our Kubernetes infrastructure (Docker, Helm) and contribute to CI/CD pipelines on Git Hub Actions.Write robust automated tests (Jest, Testcontainers) and keep shared libraries modular and reusable within the Moon monorepo.Participate in design discussions, code reviews and architecture decisions;

mentor other engineers and promote engineering excellence. WHAT WE ARE LOOKING FORMust have: 8+ years of professional backend software engineering experience.Strong proficiency in Type Script and Node.Js,



with production experience in Nest JS.Hands‑on experience with event‑driven architectures and messaging systems (NATS/Jet Stream and/or Kafka).Solid experience with distributed and No SQL data stores, ideally Cassandra, Elasticsearch and Redis, plus relational databases (My SQL, Type ORM).Strong understanding of API design (REST/HTTP, g RPC), performance optimization, caching and security best practices (OAuth2/OIDC, JWT).Experience building and running microservices on Kubernetes with Docker and Helm.Good testing discipline: unit and integration testing, including container‑based tests (e.G. Testcontainers).Comfortable working in a monorepo with build orchestration tools (preferably Moon) and pnpm. Nice to have: Nice to have: Experience with Java (21) and frameworks such as Quarkus or Spring, and/or rules engines like Drools.Nice to have: Experience with stream processing using Apache Flink.Nice to have: Working knowledge of Python (Fast API, Pydantic) and exposure to AI/ML services in production.Nice to have: Familiarity with observability practices and tooling: Open Telemetry, Pino structured logging, Sig Noz/Prometheus.Nice to have: Experience with identity and access management (Keycloak).Nice to have: Knowledge of CI/CD pipelines (Git Hub Actions) and Infrastructure as Code (Pulumi).Nice to have: Previous experience in financial services, fraud detection or compliance platforms.Nice to have: Contributions to open-source projects or technical communities. WHY JOIN ACORU? Remote‑first culture with flexibility and autonomy. High ownership.23 days of vacation + Birthday off + 2 Christmas days4 day work-week in AugustYour backend expertise will directly contribute to building a more secure and transparent financial ecosystem, revolutionizing financial intelligence and security. #J-18808-Ljbffr

📌 Senior Backend Engineer (Madrid)
🏢 Acoru
📍 Madrid