Why Mend.io

We are redefining how modern organizations secure software from open source and custom code to AI-generated components. As the creators of the first AI Native AppSec Platform, we help global enterprises stay safe, fast, and compliant in an era of AI-driven development. Our platform combines intelligent automation, deep risk visibility, and developer-first experiences, shaping the future of application security.

We are also committed to building a collaborative, empowering workplace. If you are excited about this role but do not meet every requirement, we encourage you to apply. Your perspective could be exactly what we need!

Mend.io is building the next generation of application security for AI-powered software, and Mend AI is the team leading that bet. Our product detects and secures AI/ML components inside applications - addressing emerging risks like prompt injection, data leakage, and adversarial attacks - in a domain where the standards are still being written.

We're looking for a Principal Software Engineer to take end-to-end ownership: from research and design through production, on systems that combine classical algorithms with AI/LLM-based capabilities. This is an AI-native role in both senses - you'll build security for AI systems, and you'll work AI-first yourself, using coding agents across the development lifecycle and knowing how to get consistently high-quality results from them.

You'll work as a senior individual contributor with real influence over architecture and product direction, collaborating directly with security researchers, data scientists, and product managers across our Poland and Israel teams (1-hour time difference - genuine daily collaboration, not satellite work).

What You'll Do

• Own solutions end to end - from studying the domain and generating your own ideas, through research and design, to coding, shipping, and supporting them in production.

• Drive independent research in a new domain where problems are not fully defined, balancing innovation with practical, cost-effective engineering

• Build and evolve backend & frontend, extending traditional microservices with AI/LLM-based capabilities

• Use AI agents throughout development - research, design, coding, and testing - to raise both speed and quality

• Work closely with security researchers, data scientists, and product managers to turn ideas into shipped product

What We're Looking For

• 10+ years of backend software engineering experience, including 3+ years in a hands-on technical leadership role (Principal / Tech Lead / Architect)

• A product mindset: you connect technical decisions to business impact

• A team player with excellent communication skills, who’s not afraid to touch every aspect of modern software product development (e.g. quality, documentation, customer-facing technical discussions)

• Proven experience designing and building systems from scratch in a product environment - including reliable, concurrent, thread-safe services

• Strong hands-on skills in a modern backend language (Go or Python preferred) and the ability to pick up new languages and technologies quickly

• Real, hands-on experience using AI coding agents across the development lifecycle - you know their strengths, their failure modes, and how to guide them to high-quality results

• Solid grounding in cloud environments and modern development practices (AWS, GCP, or Azure)

Nice to Have

• Familiarity with AI security challenges (prompt injection, model leakage, adversarial attacks)

• Experience integrating AI/LLM capabilities into real-world production systems - beyond out-of-the-box API calls (tuning, customization, evaluation)

• Experience with ML workflows (training, deployment, inference) or tools such as LangChain, Hugging Face, or provider SDKs

• Background in application security, cloud security, or DevSecOps

Why Mend.io

Mend.io is an established leader in application security - an AI-native AppSec platform trusted by enterprises worldwide. Mend AI operates like a startup inside that stability: a small, senior team with a greenfield mandate, direct access to decision-makers, and a product in one of the fastest-moving spaces in security. Our Poland team is a core engineering site, not an outsourcing arm - architecture happens where the engineers are.

Mend.io is an equal opportunity employer. All aspects of employment are based solely on merit and professional competence, and we're committed to a diverse, inclusive workplace where everyone can do their best work.

Our Culture

At Mend.io, we are leading the way in securing AI-powered applications, and we believe the best innovations come from teams where everyone feels valued. We are committed to a workplace built on respect, trust, and growth, where learning and flexibility empower people to do their best work.