security engineer in SaaS

Factorial builds AI Business Management Software for companies of all sizes. Its platform centralizes workflows across HR, Finance, Talent, Operations, and IT, helping teams reduce manual processes. Factorial is a SaaS company headquartered in Barcelona.

• Perform proactive penetration testing across applications, APIs, infrastructure, and AI-powered features;
• Reproduce and validate vulnerability reports submitted by third parties, including the bug bounty program;
• Collaborate with development teams to remediate security findings and improve secure coding practices;
• Improve vulnerability validation, triage, and remediation processes;
• Hunt for recurring or legacy vulnerability patterns through root cause analysis, previous incidents, and security findings;
• Build and improve security automations, agents, skills, and CI/CD controls;
• Help secure the use of AI across product and internal workflows, including LLMs, agents, data access, tools, permissions, and abuse scenarios;
• Contribute to the development of security tools, automations, and infrastructure;
• Stay up to date with security research, threats, attack techniques, and emerging AI security risks.

• 3+ Years of professional experience in Application Security, Offensive Security, or Penetration Testing;
• Mandatory experience in Web Application Penetration Testing;
• Degree in Engineering or Computer Science;
• Strong knowledge of web applications, databases, network protocols, operating systems, cybersecurity fundamentals, CVSS, testing methodologies, and tooling;
• Proficiency in scripting or programming languages used in security testing and automation, such as Python or Bash;
• Ability to work across different security problems and reason critically;
• Ability to build tools, automations, guardrails, and scalable practical security solutions;
• Curiosity and willingness to learn AI security topics, including LLM testing, prompt injection, agentic workflows, data exposure, tool permissions, RAG security, and secure AI adoption;
• Fluent English;
• Nice to have: BSCP or eWPTX certifications, experience with Ruby / Ruby on Rails applications.

• Base salary of 40.000 - 55.000€ plus 7-10% variable performance pay paid quarterly;
• ESOP plan;
• Alan private health insurance;
• Wellhub gym, pool, and outdoor class benefits;
• Cobee expense savings;
• Language classes;
• Breakfast at the office and organic fruit;
• Food discounts with Nora;
• Pet-friendly workplace;
• On-site work several days a week (80%) with remote work supported when it makes sense (20%);
• Office-first, flexible approach.