Forward Deployed Engineer (FDE) in London

Reasonable is the applied AI research company building formal verification for post-human software development. Correctness guarantees for software developed by humans and machines are no longer impractical or prohibitively expensive. Code generated by AI can be provably correct, rather than plausibly functional. At Reasonable, we are doing the research, training the models, and developing the products required to make this a reality. Achieving this creates a new paradigm for high accountability software development and unlocks the full potential of AI for professional engineers. We're a compact, talent-dense technical team, with deep domain expertise in machine learning, formal verification and mathematical models of program semantics. Join us to develop the next frontier of formal reasoning and software engineering.

The Role

As a founding Forward Deployed Engineer (FDE), you will help shape how we solve problems for our partners, and set the patterns that will be inherited by the customer-facing hires that follow. Working alongside Ferenc and Craig, you'll be at a design partner's whiteboard as much as you're in our codebase. The role is just as much discovery and translation as it is development and deployment. Your work will be instrumental in figuring out how formal verification should fit into the rapidly evolving stack and workflow of the most sophisticated engineering teams on the planet.

You Will

• Lead discovery by joining early customer meetings, owning technical scoping, and bringing research depth to prospective partner conversations.
• Diagnose which of a prospective partner's systems are fit for verification and proof of concept (POC) work. POCs must solve real and replicable problems.
• Design POCs and initial customer solutions with us, translating observations and requirements into tightly scoped deployments a small team can deliver rapidly.
• Identify capability gaps which recur across partners and feed those signals directly into our research and development direction: what we train for, what we build.
• Elicit real specifications from complex systems and world-class engineering teams. Build trust while translating between prospective partners and the frontier where AI meets formal verification.
• Stay hands-on between partner conversations. You are a key member of technical staff, building alongside the wider team. This is a technical role, end to end.

Requirements

We're Looking For

• Time spent inside or close to a high-accountability engineering culture in the mould of a Stripe, Cloudflare, AWS, Datadog, MongoDB or similar; you understand the value of correctness and verification.
• Familiarity with systems languages like Rust, JVM languages like Java/Kotlin, or cloud-native languages like Go.
• Domain expertise in formal methods or verification, either from research or from practical application.
• An understanding of specification-aware programming (Verus, Dafny, Viper), proof assistants and verification tools (TLA+, Lean, Roq, Isabelle).
• Experience building relationships with senior engineers and CTOs.
• Genuine interest in the commercial side of our work.
• Comfort with and excitement about the early-stage version of this work: consistently world-class output, despite ambiguity, hands-on scrappiness, and rapid iteration.

Bonus Points If You

• Actively contribute to formal verification or program synthesis projects: Verus, Lean, Dafny, or similar.
• Have run production back-end services at scale; you've felt the pain of what testing can't prove.
• Have been accountable for distributed systems; you respect the failure modes that emerge from concurrency, consensus, and partial failure.

This is an unusual profile. If that's you, get in touch. If you are close to it, we still want to hear from you! If you know someone that would be ideal, we always reward great introductions.

Benefits

• Compensation: Generous salary, with equity and additional benefits.
• Location: San Francisco or London, with flexibility for customer and team travel - expect to be in-person frequently with Craig (SF, London) and Ferenc (Budapest, London).
• Visa sponsorship: available in both geographies for the perfect candidate.
• World-class team and environment: an opportunity to build alongside deeply experienced founders, in a well-funded company that's backed by industry leading VCs and angels including Oriol Vinyals, Zoubin Ghahramani, Jonathan Frankle and Guy Podjarny, amongst many others.