Software Engineer, C/C++ - France

Email remains the backbone of global communication and one of the most targeted vectors for cyberattacks. With the rapid advancement of LLMs and AI agents, sophisticated, AI-driven attacks have become an increasingly critical threat to businesses.

We are looking for a Software Engineer to join our Filtering Technologies team within the Security Lab and help us shape the next generation of cybersecurity products. The Security Lab is an international team (Europe, North America, Japan) of engineers and security analysts that builds and operates the technologies that protect over 75,000 businesses worldwide.

You will contribute to the evolution of two core technologies:

• Hornet email filter: Our proprietary high-performance email filter protects 1.4 billion mailboxes worldwide against malicious emails. The email filter is at the heart of Hornet ATP (Advanced Threat Protection), protecting business customers against phishing, Business Email Compromise (BEC), spear phishing, and ransomware. It is also used by large telecom operators and OEM customers. The email filter is updated 24/7 by our Global Threat Center (SOC team).
• GNI (Global Network Intelligence): Our large-scale data platform ingests billions of data points every day from our cybersecurity technologies (including the Hornet email filter instances), enriches and correlates them, computes detections/risk, and produces decisions and automated actions.

You will work primarily in C/C++, Go, and Python. While the knowledge of C/C++ is mandatory for the position, the knowledge of Go and Python is optional. If you are not proficient in Go and Python, you will be given the opportunity to learn these programming languages.

Your Job:

• Building and evolving the Hornet email filter, its surrounding ecosystem and the GNI platform
• Industrializing unit, functional, security, and performance tests through CI/CD pipelines
• Containerizing applications and preparing them for production deployment in collaboration with the DevOps team
• Participating in teamwork and code reviews
• Collaborating with cross-functional teams (Product, IT, DevOps) and other Security Lab teams

Your Profile:

• Strong proficiency in C/C++ is mandatory
• Minimum 3 years of software development experience
• Knowledge of Git and Linux
• Strong problem-solving skills and an autonomous, rigorous, and well-organized approach to work
• Willingness to learn
• Ability to work effectively in an international team, with professional proficiency in written and spoken English
• A genuine eagerness to adapt, especially in the rapidly evolving landscape of AI and LLMs

Nice-to-have:

• Knowledge of Go
• Knowledge of Python
• Hands-on experience with AI-assisted development tools (such as Cursor, Codex, Claude Code, etc.)
• Strong interest in scalability, high-throughput systems, and performance engineering
• Strong interest in cybersecurity
• Knowledge of SMTP

Your Benefits:

• Flexible hybrid work arrangement
• Meal vouchers: €10 per voucher (including €5.92 contribution from Hornetsecurity)
• 100% coverage of public transportation costs
• Health insurance & supplementary pension plan (Axa)
• Sports and wellness benefits (subsidy provided)
• International exchange program