Senior Backend Python Engineer - Cybersecurity

Who we are?

HarfangLab is a French scale-up specializing in cybersecurity that develops EDR (Endpoint Detection and Response), EPP (Endpoint Protection Platform ), and ASM (Attack Surface Management) solutions to detect and neutralize modern cyberattacks targeting an organization’s workstations and servers. Our engines, models, and algorithms identify abnormal behaviors and either generate security alerts or block program execution.

Since our creation in 2018, HarfangLab’s technology has received strong industry recognition, earning prestigious distinctions and becoming the first EDR to be certified by ANSSI in 2020, and later the first to obtain ANSSI qualification in 2025. We are also proud to have joined the French Tech 2030 program alongside 80 other innovative French companies, at a time when cyber resilience has become a major strategic priority for Europe.

We have raised a total of €30 million, enabling us to strengthen our teams, growing from 40 employees in 2023 to 130 today, and expand internationally across Europe.

Today, HarfangLab protects the endpoints of more than 800 clients of all sizes and across all sectors: CAC 40 industrial companies, government entities, SMEs, hospitals, and local authorities. With a strong collective spirit and international ambitions, HarfangLab continues its expansion while remaining true to its original mission: protecting organizations against increasingly complex cyber threats while enabling clients to retain full control over their data.

Why are we hiring?

Entreprise's growth continues, and we have plenty of ideas on what we want to enhance in the product.

What you will do with us?

As a Senior Python Back End Developer, you will be responsible for developing the backend of our EDR, which stores, processes, and displays telemetry data collected from the IT infrastructure. The backend plays a central role in the product, requiring daily interaction with frontend, agent, and devops teams as needed.

Your responsibilities will include:

• Taking ownership of key product features, from technical design to implementation, deployment, and maintenance.
• Driving architectural decisions and ensuring the scalability and performance of a platform processing data from over 100,000 connected machines.
• Ensuring the reliability and resilience of our backend systems deployed on-premise at customer sites.
• Identifying technical risks and proactively improving the codebase, development practices, and system architecture.
• Contributing to internal tooling and engineering processes to improve team productivity and software quality.
• Mentoring engineers through code reviews, knowledge sharing, and technical guidance.
• Collaborating with Product and Engineering teams to deliver robust, scalable, and maintainable solutions.

Our tech stack includes Python, ElasticSearch, Kafka, and Kubernetes!

About you

Hard Skills

* Degree in engineering, computer science or similar technical field,

* At least 4 years experience in Python backend development,

* You are familiar with ElasticSearch, Kafka, or Kubernetes,

* You have experience with web development in Django or Flask,

* You master the use of profiling tools for Python (cProfile, memprof, py-spy),

* You are comfortable leveraging AI-powered coding tools to improve development efficiency, code quality, and troubleshooting.

Soft skills

• Problem solver: You have strong analytical skills, you are creative, and you love solving complex problems,
• Collaborative Team Player: You excel in collaborative environments, valuing teamwork and the collective achievement of goals,
• Independent Contributor: You thrive in autonomy, demonstrating the ability to take ownership of projects and tasks. Your self-motivation allows you to navigate and excel in tasks with minimal supervision.

About us

Our office and Team Life:

• Offices located in the heart of Paris, near Bourse (75002),
• High-quality equipment based on preferences and needs (PC, Mac, additional screens, etc.),
• Thanks to our Office Manager, we regularly organize events such as seminars, happy hours, themed evenings, and more,
• An onboarding process to welcome each new colleague with an explanation of the roles and a mentor to support you during your early days!"
• A great team that always seeks to improve their skills

And more:

• An attractive package: Base salary (63000 to 74000 euros) + profit sharing,
• Flexible remote work options,
• A mentor to guide you throughout your probationary period,
• Health insurance: The best health insurance with Alan,
• Meal vouchers: We use the Swile card and also have access to a discount platform through our works council,
• 7 to 11 additional days off (RTT) per year, in addition to the 25 days of paid vacation.
• GymLib subscription, covered 80% by HarfangLab,
• Access to training and events of your choice and according to your professional needs.

The recruitment process

• A 30-minutes call with our Talent Acquisition Manager,
• A 30-minutes visio interview with the Hiring Manager,
• A 1 hour on-site interview + 30 minutes with the team for a team fit assessment,
• A psychometric test to assess your motivations and soft skills,
• A final HR video appointment to review your soft skills and motivations.