Founding Senior Software Engineer

Founding Senior Engineer Product & Platform · London · 3 days per week in office CodeWall is hiring its founding engineering team. This is a rare opportunity. We're early enough that the architecture, product, engineering standards and culture are still being set — but far enough along that the fundamental bet is working. We have paying enterprise customers, real revenue and strong early demand for what we're building. We're building autonomous offensive-security agents that find and prove vulnerabilities in real customer environments. They're already uncovering critical vulnerabilities in systems built and operated by some of the world's most sophisticated organisations. Now we're building the engineering team that takes that foundation and turns it into a world-class product and platform. As a Founding Senior Engineer, you'll have an unusually broad mandate: building the product security teams work in, evolving the distributed platform our agents run on, and helping establish how engineering at CodeWall works. There is plenty already here — working technology, real customers and hard-won learning — but very little is sacred. The architecture, product and ways of working will evolve substantially as we scale. You'll be expected to understand what exists, preserve what's good, challenge what isn't, and help decide what comes next. Most engineers have to choose between founding-team ownership and a product with genuine customer pull. Here, you get both. What you'll work on Build the product end to end. Ship the surfaces security teams work in — findings and evidence, reporting, asset inventory, scheduling, integrations and the workflows around them. Turn what our agents discover into something customers can understand, trust and act on.Evolve the platform our agents run on. Build for long-running, concurrent offensive-security workloads, owning the reliability, capacity, latency and cost characteristics that come with them.Engineer for an unusual threat model. Our platform intentionally runs offensive tooling against customer environments. Authorisation, tenant isolation, secrets, controlled execution, threat modelling and auditability are fundamental architectural concerns here.Make AI-native engineering real. Develop the agent workflows, evaluations, guardrails and tooling we use to build and operate CodeWall. Engineers own the loop: you'll improve the harness, not simply work inside it.Help establish engineering at CodeWall. Own what you build in production and help set the architecture, infrastructure, testing, observability, delivery and engineering standards the team that follows us will inherit. There are substantial platform and scaling decisions ahead, and you'll be one of the people making them. We'd like to meet you if You're an exceptional software engineer who has built and operated meaningful production systems. You're strong in Python, modern backend development, SQL and relational data modelling.You've shipped customer-facing product and care about whether something should be built, not just how to build it.You've owned systems after deployment — operated them, debugged failures under real load and made them more reliable afterwards. You're comfortable across containers, cloud infrastructure and infrastructure-as-code.You have strong security instincts. You understand authorisation, secrets, isolation and threat modelling, and know when a design deserves suspicion.AI is already part of how you engineer software. You've gone beyond autocomplete: you've worked seriously with agents, learned where they fail and developed ways to verify their output.You have genuine breadth and a bias towards ownership. When something important crosses a boundary, your instinct is to solve the problem rather than defend the boundary — and you raise the standard around you without needing to be the loudest person in the room. We care much more about evidence of exceptional engineering and ownership than a particular number of years on your CV. Particularly interesting You don't need these, but we'd be especially interested if you have experience with one or more of: Offensive security — pentesting, security research, bug bounty, CTFs — or building tools for security practitionersTypeScript and React, and the ability to take a feature all the way through to the interfaceDurable execution and distributed workflow systemsMulti-tenant SaaS running untrusted or adversarial workloadsScaling or re-platforming live production systems Don't self-select out because you don't tick every box. If the problems above sound like your kind of problems and you think you'd be dangerous here, we want to hear from you. Come and hack the planet with us. Why CodeWall CodeWall is building autonomous AI agents that think and operate like elite hackers: continuously finding and proving vulnerabilities before real attackers can exploit them. We recently closed a $4 million pre-seed round, backed by exceptional investors. More importantly, the product is already in the hands of paying enterprise customers and generating real revenue. The technology is already producing extraordinary results. CodeWall's agents have uncovered critical vulnerabilities across major global platforms, including an unauthenticated endpoint exposing 3.17 trillion rows of data, hardcoded credentials found in under 18 minutes, and a CVSS 9.8 organisation takeover created by chaining four seemingly harmless weaknesses. Our ambition is to build the world's best AI super-hackers and the defining offensive-security company of the AI era. Read our manifesto and research at codewall.ai. How we work Judgment and urgency. Much of this job is deciding what matters and acting on it. We hire people who make that call well, repeatedly, without waiting to be told. We have genuine customer pull and a market moving extremely quickly. We intend to capitalise on it. Ownership runs end to end. The people who build CodeWall talk directly to the security teams using it, ship what they build and operate it in production. Nothing important is beneath anyone and nothing gets thrown over a wall. Direct, without sharp elbows. We say what we think early. We're hard on problems and easy on people, and the bar for how we treat each other doesn't drop when the pressure rises. Conviction is welcome; ego isn't. AI-first. The engineers using our development harness are also responsible for improving it. AI-generated work is held to exactly the same engineering standard as human-generated work. We work from our London office three days a week. At this stage, with this much still to invent, we believe engineering is faster and better when we spend meaningful time in the same room. CodeWall is an equal opportunity employer. We welcome applicants regardless of race, colour, religion, gender identity, sexual orientation, national origin, age, disability or veteran status. If you need an accommodation during the hiring process, just let us know.