Staff Security Engineer.

The Opportunity

We’re looking for a hands-on Senior or Staff Security Engineer to lead and own security across the company.

Part of the job is the work every company needs and too few do well: hardened cloud infrastructure, least-privilege access, secure delivery, vulnerability management, penetration testing, and incident response. The threats in this space are increasing exponentially. The other part is an evolving domain with no playbook. Our product runs agents that read untrusted content, execute code, and hold credentials. Attackers now use AI to probe and fuzz faster than before. Prompt injection, data exfiltration through allowed channels, cross-session access, and insecure agent-written code reaching production are real risks for us today, not research topics.

We want someone who will help us close the obvious gaps without being asked, and finds the problems nobody has written down yet.

You'll work closely with our ITOps, platform and product engineers. Teams own their services and platform owns the monorepo pipeline. Your job is to improve our security posture without slowing delivery: build automated controls into existing workflows rather than rely on slow, blocking manual AppSec reviews. You'll test whether those controls hold, address critical risks, and take responsibility for security outcomes, not just recommendations.

Key Responsibilities

This is a hands-on role - you'll be in the code, infra, and pipelines yourself.

• Set security priorities and drive fixes through to verified completion;

• Find application vulnerabilities through code review, penetration testing and agent-specific red-team exercises;

• Work with ITOps, platform and product engineers to harden infrastructure and build security into delivery pipelines;

• Build detection for user and agent activity, and lead incident response.

Essential Qualifications

• Strong application security background - you can spot exploitable flaws, and explain the fix;

• Hands-on penetration testing and offensive security experience across web applications, APIs, and cloud infrastructure;

• Solid infrastructure and cloud security fundamentals: IAM, network segmentation, containers and isolation, secrets management, logging;

• Experience building detections and running incident response, not only reviewing them;

• Real fluency with AI coding agents and LLM-based systems - how they work, where they fail, and how they can be manipulated;

• Enough software engineering skill to build your own tooling, automation, and test harnesses;

• Sound judgment under pressure: you can weigh a risk against a release, decide, and explain the decision to engineers and founders.

Nice to Have

• Experience securing sandboxed or multi-tenant code execution environments;

• Red-team, bug bounty, or CTF track record;

• Experience with security programs and compliance frameworks (ISO 27001, SOC 2) in a small company.

Why Join Zencoder?

• Impact AI is reshaping how work gets done, and you'll be at the forefront of that shift, building a product that enables teams to get more done with AI. We use our own products every day, so you'll see how your work lands right away.
• AI-First We use AI to expand what one person can accomplish. You'll constantly rethink how you work: what to hand over to AI, and where your own judgment matters most.
• Ownership We keep the team small and give people real scope, autonomy, and equity. You'll take initiative, make decisions, and see your work through to real outcomes, raising the bar with every iteration.
• High Talent Density A small team of highly capable people moves faster and builds better. You'll work directly with senior teammates and our founder, Andrew Filev, in a flat structure where ideas win on merit, not titles.
• Remote-First We hire globally, prioritizing talent over location, so you can work where you're most productive. Prefer in-person? We have a hub in Barcelona with weekly co-working.