Location: London, England, GB

On-Site | Full-time

Compensation: £110K - £150K GBP

Our client is a high-velocity, London-based applied research lab reshaping the future of B2B operations and sales. By building highly intelligent, agentic workflows and automating high-volume execution, they empower businesses to focus on deep, high-value human connections. Operating as a talent-dense, seed-stage, revenue-generating startup, the team ships to production daily, tackles highly ambiguous engineering challenges, and works at the cutting edge of AI capabilities.

They are seeking a Staff Engineer to serve as one of the most senior Individual Contributors (ICs) on the engineering team. In this player-coach role (~70% IC, ~30% technical leverage, mentoring, and architectural leadership), the successful candidate will not simply execute tickets, but will instead own complex, ambiguous problem spaces end-to-end.

This is a fully on-site role based in Piccadilly, London, designed for a builder who thrives in a fast-paced, highly collaborative, and high-standard engineering culture.

Key Responsibilities

• Own Complex Architecture: Lead the design and development of the core systems powering AI agents, LLM evaluations, high-throughput data pipelines, and robust provider waterfall systems.
• Drive End-to-End Execution: Transition ambiguous, cross-cutting problems from initial concept to shipped production code, ensuring real-world performance is measured and optimized.
• Set Technical Standards: Maintain a clean, scalable, and highly performant codebase, making long-term architectural decisions that will guide future team growth.
• Provide Technical Leverage (~30%): Raise the engineering bar across the organization by authoring clear technical design documents, conducting thorough code reviews, and mentoring mid-level and senior engineers.
• Collaborate Directly with Leadership: Partner closely with the founders and the Head of Engineering to shape the technical strategy, product roadmap, and overall system scalability.
• Strive for Continuous Improvement: Engage directly with customer feedback and product usage metrics to design, build, and deploy enhancements within days.

Requirements

Mandatory Experience & Background

• High-Calibre Tech Pedigree: Proven experience at a top-tier, high-velocity technology company (such as FAANG, Bloomberg, Stripe, Shopify, Revolut, Datadog, or high-growth, venture-backed scale-ups/YC alumni) is strictly required for this role.
• Seniority & Track Record: 6+ years of production-level software engineering experience with a demonstrated capability of operating independently on "zero-to-one" initiatives.

Technical Profile

• Modern Web Stack Expertise: Deep experience working with TypeScript and modern web infrastructure. The current stack utilizes Next.js (App Router), Trigger.dev, and Postgres/Drizzle.
• Systems Engineering: Strong systems thinking with hands-on experience designing distributed architectures, robust background job infrastructure, or scalable data pipelines.
• Practical AI/LLM Experience: Solid familiarity with LLM-based systems, prompt engineering, structured outputs, evaluations, and agentic workflows. (While background model training is not required, experience shipping resilient LLM-powered features in production is key).

Professional & Operational Attributes

• Location Alignment: Absolute willingness and ability to work on-site 5 days a week at the Piccadilly, London office (this is a firm, non-negotiable requirement).
• Bias to Action: A strong preference for shipping high-quality, working iterations quickly over prolonged design phases.
• Clear Communication: Exceptional written and verbal communication skills, with the ability to articulate complex technical decisions through structured design documents.

Benefits

• Competitive Compensation: Market-leading salary with a highly flexible equity/stock-for-salary trade-off, designed for builders who want significant upside in a growing, revenue-generating startup.
• Comprehensive Coverage: Private health insurance, dental coverage, and a competitive pension scheme.
• Workplace Perks: Fully catered late-evening support, including company-funded dinner and taxi transportation home for those working past 8:00 PM.
• Visa Sponsorship: Full visa sponsorship is available for qualified international candidates.

Interview Process

Our client utilizes a rigorous, transparent two-stage evaluation process designed to respect candidates' time while deeply assessing technical capability:

1. Systems Design Interview: A deep-dive session focused on mapping a complex, ambiguous problem statement into a robust, scalable system architecture. This stage evaluates high-level technical decision-making and systems thinking.
2. Take-Home Assessment: A practical, hands-on exercise using an application scaffold. Candidates will be asked to utilize an AI agent to solve a problem and must be prepared to discuss, evaluate, and defend the AI agent's outputs.