Job Description

Senior Software Engineer

Location: Warsaw, Poland
Working Model: Hybrid
Initial Arrangement: Remote during the first months, transitioning to hybrid
Employment Type: Full-time
Department: Engineering

The Opportunity

We are working with a globally recognised technology business operating at the intersection of cryptocurrency, financial technology and digital assets.

The business is building a new product from the ground up, with the engineering team starting from a blank repository using Rust. The project is at an early stage, meaning the successful candidate will have genuine influence over the architecture, engineering standards and technical foundations of the platform.

This is an opportunity for a senior engineer who wants meaningful ownership rather than simply contributing features to an established codebase.

The Role

As a Senior Software Engineer, you will design and build the core services that underpin the product, taking significant ownership from initial design through to production.

You will work closely with Product and Design, contribute to architectural decisions, establish engineering standards and help determine how the system evolves as the product scales.

Because the foundations are still being established, your technical judgement will have a direct impact on the long-term architecture.

Key Responsibilities

Architecture & Backend Engineering

• Design and build the core services powering the product, including APIs, data models and integrations

• Make architectural decisions that establish the technical foundations of the platform

• Identify which technical decisions are difficult or expensive to reverse and apply appropriate engineering judgement

• Design scalable, maintainable systems capable of supporting significant future growth

• Own substantial areas of the product from initial design through production

• Contribute to technical strategy and system design as the platform evolves

API & Platform Development

• Design and develop production-grade REST APIs

• Establish robust API contracts and versioning strategies

• Build services that are reliable, observable and maintainable

• Develop integrations with internal and external systems

• Consider scalability, security, performance and operational resilience throughout the development lifecycle

Production Ownership

• Take end-to-end ownership of services through development, deployment and production

• Participate in on-call responsibilities and incident response

• Diagnose and resolve production issues

• Build and improve monitoring, instrumentation and operational processes

• Ensure systems are designed with reliability and maintainability in mind

Engineering Standards

• Establish high standards for code quality, testing and maintainability

• Conduct thoughtful code reviews and provide constructive technical feedback

• Mentor other engineers and contribute to the development of engineering best practices

• Help establish testing, observability and CI/CD standards across the platform

• Raise the overall technical quality of the engineering organisation

Product Partnership

• Work directly with Product and Design to translate requirements into robust technical solutions

• Challenge requirements where necessary and provide engineering-led alternatives

• Balance speed of delivery with long-term technical sustainability

• Help shape the product rather than simply implementing predefined specifications

AI-Assisted Engineering

• Use modern AI coding tools as part of the software development workflow

• Apply strong engineering judgement when reviewing and validating AI-generated code

• Know when AI-assisted development can accelerate delivery and when its output requires significant modification or rejection

• Help establish effective practices for incorporating AI tools into professional software engineering

What We're Looking For

Required

• 5+ years of professional software engineering experience

• Demonstrable experience owning and operating production systems, not simply delivering individual features

• Strong production experience with Rust, with additional experience in Go, Java or Kotlin highly relevant

• Proven experience designing and building REST APIs at scale

• Strong understanding of API contracts, versioning and long-term API design

• Deep experience with AWS or an equivalent cloud environment

• Strong experience with containers and CI/CD

• Experience building, improving or hardening cloud infrastructure and deployment pipelines

• Comfortable using AI coding tools while maintaining strong engineering judgement and code ownership

• Experience mentoring engineers and/or leading significant technical initiatives

• Strong written and verbal English communication

• Self-directed and comfortable operating with significant technical ownership

• Bachelor's degree in Computer Science or equivalent professional experience

Nice to Have

• Experience with payment infrastructure such as SEPA, SWIFT, ACH or card issuing

• Experience working within regulated fintech environments

• Familiarity with PSD2, KYC/AML and PCI DSS requirements

• Experience with cryptocurrency custody, on-chain settlement or stablecoin infrastructure

• Experience with monitoring and analytics platforms

• Previous responsibility for establishing technical architecture on a product from its earliest stages

• Strong understanding of blockchain fundamentals, including ERC-20, RPC nodes, UTXO models and account-based models

• Experience working within highly regulated financial or digital asset environments

What Success Looks Like

• Core services are architected and built on a scalable technical foundation

• APIs and data models are designed with long-term maintainability in mind

• The platform is reliable, observable and production-ready

• Engineering standards around testing, code quality and CI/CD are established and consistently applied

• Technical decisions are made with an appropriate balance between speed and long-term architecture

• Other engineers are supported through mentorship and strong technical practices

• The product can scale without requiring significant architectural rework

The Ideal Candidate

The ideal candidate is a senior backend or platform engineer who enjoys working at the point where architecture is still being defined.

You should be comfortable taking ownership of systems in production, making decisions with incomplete information and working closely with product stakeholders. You will have strong production Rust experience and be capable of influencing technical direction rather than simply implementing an existing architecture.

Experience in fintech, payments or digital assets is highly relevant, particularly where you have worked with regulated financial infrastructure, payment rails or blockchain-based systems.

Location

Warsaw, Poland.

The role will initially allow remote working during the first months before transitioning to a hybrid working model in Warsaw.