Software Engineer I

About RunSybil Founded in 2023 by Ari Herbert-Voss and Vlad Ionescu, RunSybil is on a mission to automate hacker intuition. We’re building Sybil: an AI-driven pentester that discovers vulnerabilities before they’re exploited. As adversaries adopt AI to increase their attack surface, we’re putting cutting-edge offensive security into the hands of defenders. Backed by strong investor support and early customer traction, our team is composed of experts from OpenAI, Meta, Mandiant, Palantir, Cruise, Trail of Bits, and Aptiv.

About

the Role We are looking for a Software Engineer I who wants to do the best work of their first years anywhere. You will ship customer-facing features from your first weeks, build the agentic systems that power Sybil, and work directly alongside senior engineers and our founders every day. On a team this small, your code goes to production and customers use it. There is no shadow work here. This is a role for someone who builds because they want to. The strongest people we know at this stage have a trail of side projects, open source contributions, and things they taught themselves because a problem got under their skin. If that sounds like you, we will give you real ownership, fast feedback, and problems worth growing into.

What You'll Do Ship customer-facing features end to end, from first commit through production, with close review and support from senior engineers Build and extend the agentic systems behind Sybil, working primarily in Python with TypeScript and React across the stack Use LLMs as a core part of how you work: prompting, evaluating generated code, and building tooling that makes the whole team faster Own small projects yourself, including scoping the problem, proposing the approach, and seeing it through to done Debug real issues in a production system that customers rely on, and learn how long-running agentic workloads behave in the wild Contribute to technical design discussions and code reviews, and speak up when you see a better way Learn offensive security on the job from a team that includes some of the best in the field We're Looking For Someone Who Has A Mix of The Following Strong Python fundamentals and real comfort with data structures; you write clean, working code and can explain every line of it Evidence of shipping software in any setting: internships, team or class projects, research, or personal projects all count equally A habit of initiative: times you took on more than the assignment asked, fixed the thing nobody owned, or taught yourself what the work needed Hands-on experience coding with LLMs, and judgment about when to use them, how to validate their output, and when to just write the code yourself Fast, honest communication; you say what you know, what you do not, and where you are stuck Coachability: you take a hint, run with it, and carry the lesson forward Familiarity with modern JavaScript and React is a plus Location : NYC (Hybrid) Salary : The base salary for this full-time position ranges from $135,000 - $165,000. In addition to base salary, we offer meaningful equity. We want everyone here to have ownership in what we're building.: Diverse teams build better products. RunSybil is committed to hiring people who bring different perspectives, lived experiences, and backgrounds to our work. We encourage candidates of all races, ethnicities, gender identity and expression, sexual orientation, disability or medical conditions, ages, religions, and socioeconomic backgrounds to apply. Pursuant to the San Francisco Fair Chance Ordinance, we will consider for employment qualified applicants with arrest and conviction records. If you're excited about this role but don't check every box, we still want to hear from you.