Freelance Kotlin Developer - Spain
This is a remote position.
Blue Code Alicante is looking for a Freelance Kotlin Developer (remote from Spain is a must) to join a high-ownership engineering team building and evolving a distributed microservices backend on AWS. You'll work across a complex domain that includes route optimization, schedule ingestion, geo-routing and carrier data, all at real scale. You'll take full ownership of services from design to production, drive architectural decisions and proactively identify and fix problems before they become incidents.
Responsibilities:
Design, build and maintain JVM-based microservices (Java / Kotlin) running on AWS ECS, App Runner and Lambda
Work with a rich data layer: PostgreSQL, DynamoDB, RedShift, Redis and S3
Build event-driven integrations via RabbitMQ and SNS
Collaborate on API design across REST (API Gateway) and BFF patterns
Instrument services with OpenTelemetry, Tempo, Prometheus and Grafana
Ship via GitHub Actions CI/CD pipelines with Docker and ECR
Work with external integrations including Auth0, GraphHopper, PostHog and Sentry
Participate in architecture decisions and technical direction
Requirements
Minimum 6 years of professional backend development in Kotlin / Java
Solid understanding of distributed systems design, microservice patterns and event-driven architecture
Hands-on production experience with AWS (ECS, Lambda, S3, RDS or DynamoDB)
Experience with relational databases (PostgreSQL) and NoSQL (DynamoDB or similar)
Strong command of Docker and containerized deployments
Experience with CI/CD pipelines (we use GitHub Actions)
Clean code as a practice
Registered as a freelance in Spain is a must
Nice to have (but not required):
Experience with message brokers (RabbitMQ, SQS/SNS)
Familiarity with observability tooling (OpenTelemetry, Prometheus/Grafana stacks)
Background in logistics, routing, geospatial or supply chain domains
Experience integrating third-party APIs (auth providers, mapping/routing engines, analytics)
Benefits
Competitive daily or hourly rate, negotiable based on experience / skills
International and dynamic work setting
Remote work model from Spain
Freelance / Contract B2B basis
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