Senior FullStack Developer - Cryptonext Security

Description

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.

Requirements

The skills you'll need

Must-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

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

Benefits

What’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.

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Senior FullStack Developer

Job Description