Principal Software Engineer, EU

Permanent contract
Paris
Fully-remote
Salary: €120K to 200K
Experience: > 10 years

Dfns
Dfns

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Questions and answers about the job

The position

Job description

Join a stellar team of leaders and experts in blockchain technology, cryptography, infrastructure, and security to build the backbone of blockchain wallet infrastructure for the next financial era. We’re hiring a Principal Software Engineer to lead the design, development, and scaling of our core backend systems. In this role, you’ll own critical projects while setting technical direction and ensuring our platform is fast, resilient, and secure. This is more than a coding role. You’ll make key architectural decisions, drive engineering standards, and mentor senior engineers. You’ll work with product, security, and leadership to align technical execution with company strategy and ensure our systems perform under the high-stakes demands of financial workflows.


Preferred experience

Responsibilities

  • Lead the design and development of scalable, secure backend services and APIs.

  • Define and evolve architecture for databases, microservices, and integrations.

  • Own mission-critical projects end to end, from requirements to production and iteration.

  • Troubleshoot and resolve complex performance and reliability challenges at scale.

  • Drive improvements to CI/CD, observability, and engineering processes across teams.

  • Collaborate with leadership to shape roadmap priorities and long-term technical vision.

  • Mentor engineers, promote best practices, and represent Dfns in client discussions.

Requirements

  • 10+ years of backend software engineering, with leadership in fintech or blockchain.

  • Mastery of TypeScript plus one or more systems languages (Rust, Go, C++).

  • Proven track record building scalable APIs, infrastructure, and developer platforms.

  • Deep expertise with databases (PostgreSQL, DynamoDB, NoSQL) and cloud (AWS).

  • Strong knowledge of microservices, CI/CD pipelines, observability, and SSDLC.

  • Familiar with applied cryptography, PKI, and secure backend architectures.

  • Exceptional problem-solving, communication, and ability to influence technical direction.


Recruitment process

Process

  • Intro call with Co-CEO (30 min).

  • Personality and cognitive tests (45 min)

  • Coding test in a language of your choice.

  • Focus interviews with the hiring panel (180 min).

    • Code review

    • Architecture review

    • Security fundamentals

    • Culture check fit

  • Final interview with CTO (30 min).

  • Reference calls and background checks.

Terms

  • Title: Principal Software Engineer

  • Salary: €120,000–200,000 per year (full-time)

  • Equity: 150–300 stock options vested over 4 years

  • Benefits: Healthcare, pension plan, and travel expenses

  • Location: European Union (remote-first, office optional)

  • Equipment: MacBook Pro + essentials

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