Senior Software Engineer

  • Paris
  • Full-Time
  • Start Date: 06 September 2021
  • Apply Now


Established in 2020, Dfns is a cybersecurity startup operating within decentralized finance (DeFi). From our office in Paris, we are building an API for digital asset security. More specifically, Dfns provides safe, cloud-native custody as a service to help companies secure cryptos & tokens.

Dfns is also a stellar team incubated at Station F (the world's biggest startup campus), the Garage (#1 blockchain ecosystem in Europe), and Techstars Future of Finance in collaboration with ABN AMRO.

Job Description

As Senior Software Engineer, you will be contributing to product development on multiple fronts.

You will participate to the execution of one of the most ambitious tech projects in Europe right now: building a security standard for a trillion-dollar crypto industry.

You will join an amazing team of leaders (Chief Technology Officer, Chief Science Officer, Cryptographers, Engineers, etc.), in a highly challenging and collaborative environment.


Your primary goal will be to take the product through the full release life cycle from its initial development (Alpha, Beta, RC) to the scaling phases (RTW, General Availability).

Your primary metric will be WTL (Weeks to Launch).

Concretely, here are the tasks to be expected:

  • Help defining the levels of priority within the product roadmap, and be accountable for the deadlines and the quality of production.
  • Act as a powerhouse of ideas on all technical issues (ops, security, architecture, stack, etc.).
  • Ensure scalability and high availability of the product, as well as top-notch code quality.
  • Build, operate, and ensure the security of the product, namely the API and the network.
  • Facilitate cross-branch communication and know-how exchange between team members.
  • Implement technical best practices and new ideas to encourage innovation within your team.
  • Work closely with the CTO and UI/UX team to transform feedback into features.
  • Participate in user research, documenting and writing requirements, and risk management.


  • Role: Senior Software Engineer (possibility to evolve)
  • Salary: €80-100K / year (+competitive YoY increase)
  • Equity: 0.1-0.5% (≈ €1-5M in 2-4 years, dilution included)
  • Location: Work from home 100% remote, in London, or Paris HQ.
  • Paid vacation: >5 weeks off / year
  • Employee benefits: transportation, perks, events, insurance, meals, office space...

Preferred Experience


  • 5+ years of experience as software engineer
  • Experience in designing and developing secure RESTful APIs.
  • Experience building secure, fault-tolerant, and resilient systems.
  • You should be very good in one of them, and be willing to learn another: Rust, Go, TypeScript, Python
  • Experience in writing Unit Tests, Integration Tests, End-to-end tests, performance tests, chaos engineering.
  • SQL (PostgreSQL) and NoSQL (whatever suits for particular job) databases.
  • Experience with one of AWS, MS Azure, or GCP.
  • Experience building Continuous Delivery pipelines, 12-Factor App, understanding how to build domain-driven micro-services.
  • Functional and Object-Oriented Programming. We will ask you to implement Reduce and Curry in one of the interviews.
  • Problem-solving competences in respect to other stakeholders.
  • Humble, respectful, and very professional to others.
  • Able to decide even in stressful, unstable situations.
  • Big appetite for Cybersecurity, Fintech, Blockchain and/or Crypto space.
  • Fluent English language skills (written/spoken).
  • (Bonus) Experience working with cryptocurrencies, integrating networks, creating smart contracts.
  • (Bonus) Working with public and private blockchain implementations
  • (Bonus) Experience integrating or developing DeFi protocols.
  • (Bonus) Experience building distributed, federated, or peer-to-peer decentralised systems.

Recruitment Process

  • 30mn screening interview with Christopher and David
  • 60mn focus interview with David and Houda
  • 60mn technical testing with David
  • 60mn who interview with Clarisse, Christopher, Houda, and David

Additional Information

  • Contract Type: Full-Time
  • Start Date: 06 September 2021
  • Location: Paris, France (75013)
  • Experience: > 5 years
  • Possible full remote
  • Salary: between 70000€ and 100000€ / year