Senior Backend Engineer - Node.js​/TypeScript​/NestJS; m​/f​/d

Bytamic is an international IT services and Consulting company with its headquarters in Vienna, Austria and subsidiary companies in Warsaw and Poznan. We work with multinational companies and we drive digital transformation for our clients. We are truly agile, work with the latest technologies and our engineers and scrum-teams deliver state-of-the-art product development services for our clients. Delivering with highest quality standards is key to us – therefore we focus on continuous training & education of our engineers.

For our Client, we are looking for a qualified partner for a Senior Backend Engineer to join an international project focused on modernizing, optimizing, and stabilizing a large-scale enterprise platform serving over 1 million users.

The project focuses on improving system performance, reliability, scalability, and software quality while modernizing the existing backend architecture. The technology stack includes Node.js, Type Script, NestJS, PostgreSQL, and React, with the platform running in a Kubernetes environment.

The main technical challenges involve event-driven architecture, advanced search capabilities, Data Lake integration, large-scale data processing, data consistency, and security in a multi-tenant environment.

We are looking for a highly experienced, hands-on engineer who combines strong backend development skills with architectural expertise and can independently identify technical challenges, propose pragmatic solutions, and take ownership of their implementation.

Seniority:
Senior / Senior+ / Tech Lead

• Analyze, refactor, and optimize an existing backend built with Node.js, Type Script, and NestJS.

• Design and implement event-driven architecture using Apache Kafka.

• Integrate backend applications with Data Lake infrastructure and implement data synchronization using Change Data Capture (CDC)

• Design, develop, and optimize advanced search capabilities using Elasticsearch.

• Identify and eliminate PostgreSQL performance bottlenecks, including moving resource-intensive analytical operations outside the transactional database.

• Modernize data processing mechanisms handling hundreds of thousands of records.

• Design reliable business processes while ensuring transactional consistency and data integrity.

• Implement secure data isolation and access control in a multi-tenant environment.

• Refactor business logic and move it from frontend components into appropriate backend services.

• Develop and maintain unit, integration, and performance tests.

• Collaborate closely with Solution Architects, Data Engineers, Dev Ops Engineers, and QA teams.

• Advanced knowledge of Node.js, Type Script, and NestJS.

• Proven experience developing and modernizing large-scale enterprise applications.

• Strong experience designing REST APIs and system integrations.

• Hands-on experience refactoring and modernizing modular monolithic applications.

• Advanced, hands-on experience with Apache Kafka, including event-driven architecture, producers, consumers, topics, partitions, consumer groups, retry mechanisms, dead-letter queues, idempotency, and error handling. Knowledge of Transactional Outbox and Saga patterns is expected.

• Advanced, hands-on experience with Elasticsearch, including index design, mappings, analyzers, query optimization, full-text search, filtering, aggregations, and synchronization with PostgreSQL.

• Proven experience integrating Data Lake solutions and processing large datasets, including CDC, ETL/ELT pipelines, batch and incremental processing, data consistency, data quality, and synchronization latency.

• Advanced knowledge of PostgreSQL and SQL, including query optimization, indexing, execution plans, transactions, locking, and concurrency management.

• Strong…