11/01/2026 updated
IM
partially available
info: Available evenings and weekends
Senior Backend Engineer · Kotlin, Java, Spring Boot, Kafka · remote, part-time
Tuzla, Bosnia-Herzegovina
Only remote
Computer Technician, secondary technical school, Lukavac (2022)About me
Backend engineer with 3+ years at a US health and wellbeing platform. I build Kafka data pipelines in Kotlin and Java on Spring Boot, PostgreSQL and AWS, and also ship Angular features. Based in Bosnia and Herzegovina (CET), available part-time and remote.
Java (Programming Language)Amazon Web ServicesPostgreSQLAngular 2+Spring BootBackendGitLabKotlinBackend ProgrammingKubernetesCassandraApache KafkaGraphQL
Kafka & Data Streaming
Expertise in building Kafka data pipelines, including Kafka Connect, Debezium change data capture, and Avro. Experience migrating services from Apache Storm to Kafka and managing large-scale message backlogs.
Kotlin & Java Backend Development
Strong proficiency in Kotlin and Java with Spring Boot, JPA/Hibernate, REST, and GraphQL. Experience building and maintaining high-throughput backend services processing hundreds of thousands of uploads per day.
Cloud & DevOps
Hands-on experience with AWS, Terraform, Kubernetes, Argo CD, Docker and GitLab CI. Took the upgraded data-ingestion service (Java 21, Spring Boot 3.5) to production.
PostgreSQL & Database Management
Proficiency in PostgreSQL and SQL for backend data storage, including identifying and resolving performance issues such as N+1 queries.
TypeScript & Web Development
Experience with Angular and Vue frameworks, SCSS, and building design-system components including accessibility improvements.
Cassandra/ScyllaDB & Redis
Knowledge of distributed databases such as Cassandra/ScyllaDB and in-memory data stores like Redis for scalable backend solutions.
Solution Design
Ability to write solution designs for backend systems, including data pipeline architecture and feature planning for health and wellness platforms.
AI Developer Tooling
Built AI developer tooling on Claude Code that was adopted by 14 colleagues within its first month of release.
Experience
Professional experience0 - 5 years
Freelancer since2026
Languages
EnglishFluentBosnianNative speaker
Project history
Building the backend for device and health data pipelines in Kotlin and Java on Kafka and PostgreSQL, handling about 615,000 mobile uploads per day. Responsibilities include fixing data loss issues, rebuilding lag alerting, migrating services from Java 8 to Java 21 and Spring Boot 3.5, designing new wellness features, building AI developer tooling, migrating survey and email processing from monolith to Kafka using Debezium, fixing notification slowdowns, and building Angular frontend features.