Senior Backend Engineer, Payments & AWS Cloud

Spirii; København; On-site; DKK 900,000 - 1,300,000; Full time

Benefits offered by this job

Flexible Work Environment

Competitive Salary Package

11% Pension Plan

32 vacation days (5 weeks + 5 extra)

Job summary

Spirii is looking for a Senior Backend Software Engineer in Copenhagen. The role sits in the Payments team, delivering backend services and cloud-native pipelines to generate invoices, credit memos, and payouts with high data integrity.

You will design scalable architectures, mentor engineers, and collaborate with Finance and ERP teams. Danish language is not required, but fluent English is needed for cross‑team collaboration.

Qualifications

• Bachelor's degree in Computer Science, Software Engineering, or a related field (or equivalent experience).
• 7+ years of professional software development experience.
• Extensive hands-on experience designing and scaling production backend systems, including event-driven, queue-based architectures.
• Strong experience building TypeScript or JavaScript (Node.js, NestJS) microservices on cloud platforms such as AWS.
• Experience leading design discussions, mentoring engineers, or acting as a technical point of contact for a team or domain.
• Hands-on experience with test-driven development, test automation, integration and load testing.
• Strong SQL and data-modelling skills, with the discipline needed for financially accurate, auditable data.
• Experience integrating external and internal IT systems, and solid API design.
• Experience with billing/payments/invoicing or other financial/transactional systems is a strong plus.
• Hands-on experience using AI assistants and/or agentic workflows to improve engineering productivity is a plus.

Responsibilities

• Designing, building, and maintaining scalable, secure backend services and cloud-native queue-based pipelines (Node.js, NestJS, TypeScript) that power data ingestion, processing, and invoice generation at high throughput.
• Ensuring data quality through correct aggregation and safe handling of late or updated records.
• Building and maintaining integrations with internal services and our ERP system.
• Significantly contributing to architectural decisions and solution design for cloud-native, distributed, event-driven systems on AWS.
• Driving automated testing and observability to protect billing correctness and catch data discrepancies early.
• Mentoring other engineers and raising the technical bar of the team through code review, pairing, and constructive feedback.
• Operating independently on ambiguous, cross-team problems with minimal oversight.
• Using AI coding assistants and agentic workflows to accelerate development and automate repetitive tasks while helping the team adopt AI safely in a financially sensitive codebase.

Skills

Backend design

Team leadership

Agile methodolgy

English communication

Education

Bachelor's degree in Computer Science or related field

Tools

AWS

Redis

SQL

NoSQL databases

ERP systems integration

TypeScript

Node.js

NestJS

Job description

Spirii is looking for a Senior Backend Software Engineer in Copenhagen. The role sits in the Payments team, delivering backend services and cloud-native pipelines to generate invoices, credit memos, and payouts with high data integrity.

You will design scalable architectures, mentor engineers, and collaborate with Finance and ERP teams. Danish language is not required, but fluent English is needed for cross‑team collaboration.