Senior FullStack Developer

Posted 14 Days Ago
Be an Early Applicant
Paris, Île-de-France
In-Office
Senior level
Information Technology • Security
The Role
As a Senior Full Stack Developer, you will create and maintain full-stack features for DISCOVERY, collaborate on architectural decisions, and implement observability tools using modern technologies.
Summary Generated by Built In
Who we are

CryptoNext Security is a deeptech startup specializing in post-quantum cryptography. We help institutions and enterprises prepare for a future where quantum computers will break current cryptographic standards.
We work with major players in finance, defense, and telecommunications, delivering cutting-edge, quantum-safe security solutions.

On a daily basis, you will

As a Full Stack Developer, you will contribute to the development of DISCOVERY, our next-generation observability and orchestration platform for post-quantum cryptography operations.

You will work across the entire stack — backend services, data flows, and frontend interfaces — collaborating closely with product, backend, and infrastructure teams.

Feature Development & Architecture
  • Design, develop, and maintain full-stack features for the DISCOVERY platform.
  • Build modern, responsive React front-ends integrated with Node.js and Kafka backends.
  • Participate in architectural decisions and propose technical improvements aligned with long-term product vision.
Backend Engineering & APIs
  • Design and implement REST and event-driven APIs.
  • Ensure performance, scalability, and resilience across distributed components.
  • Collaborate with backend engineers on domain modeling, API contracts, and data flows.
Observability & Data Visualization
  • Implement advanced data visualization and monitoring features using the ELK stack (Elasticsearch, Logstash, Kibana).
  • Integrate backend logs, metrics, and analytics into frontend dashboards.
Engineering Excellence
  • Participate in code reviews and uphold high engineering standards.
  • Contribute to technical documentation and promote software craftsmanship.
  • Apply KISS, DRY, SOLID, and pragmatic engineering principles (“done is better than perfect”).
DevOps & CI/CD
  • Contribute to deployment workflows, CI/CD pipelines, and automation initiatives.
  • Work with Docker/Kubernetes-based environments to ensure smooth delivery.

RequirementsThe skills you'll needMust-have
  • 10+ years of experience in software development, ideally in a software editor or deeptech environment.
  • Master’s degree from a French engineering school or European equivalent.
  • Strong hands-on expertise in:
    • Node.js
    • React
    • TypeScript
  • Strong understanding of Docker, Kubernetes, and containerized deployments.
  • Experience with message-driven architectures (Kafka or equivalent).
  • Solid understanding of the ELK stack and its application in observability/analytics contexts.
  • Comfortable with CI/CD, Git workflows, automated testing, and modern DevOps practices.
  • Deep grasp of software design principles and maintainability.
  • Fluent in English.
Bonus
  • Experience with gRPC or other microservice communication patterns.
  • Secure coding practices and application security awareness.
  • Experience with performance-critical or network-intensive systems.
  • Background in cybersecurity or cryptographic systems.
  • Experience with AWS, GCP, or Azure.
The team you’ll be joining

You will join the R&D engineering team behind the DISCOVERY platform, collaborating with:

  • Backend engineers
  • Product managers
  • Platform and infrastructure engineers
  • The Head of Engineering
  • Cryptography experts and system engineers across the company

You will play a key role in shaping the architecture, user experience, and technical foundations of the DISCOVERY product.

Our recruitment process
  1. Introductory call with HR — background, motivations, expectations.
  2. Technical interview with an R&D engineer, including a practical coding exercise.
  3. Head of Engineering interview — system design, long-term fit, and cultural alignment.
  4. Offer & onboarding — welcome to CryptoNext!

BenefitsWhat’s in it for you at CryptoNext
  • Join a fast-growing deeptech company at the cutting edge of quantum-safe cybersecurity.
  • Work on challenging engineering problems using modern technologies.
  • Build next-generation observability tools for cryptographic operations.
  • Flexible remote policy + office in central Paris.
  • Competitive compensation aligned with your seniority and expertise.
  • Direct impact on the future of secure communications.

Top Skills

Ci/Cd
Docker
Elk Stack
Kafka
Kubernetes
Node.js
React
Typescript
Am I A Good Fit?
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The Company
Paris
28 Employees
Year Founded: 2019

What We Do

CryptoNext Security is a European software vendor based in Paris, an industry leader in quantum-proof cryptography (PQC) solutions. Our vision and the solutions we are developing are designed to manage the complete lifecycle of post-quantum migration, including the phases of discovery, remediation, and management. Founded in 2019 after 20+ years of academic research within the prestigious INRIA, CNRS and Sorbonne University, CryptoNext Security is identified by Gartner as part of its Top 5 in PQC and is, to date, the first European company selected by NIST's NCCoE group dedicated to the best PQC migration practices. We are developing an integrated, quantum-safe remediation suite allowing for the automation of PQC migration for IT/OT systems, infrastructures and applications. Our objective is to help businesses and HW/SW vendors face the quantum threat in an efficient, agile and sustainable way.

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