Staff Engineer in London

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:

• 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.
• 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.

Due to the high volume of applications we anticipate, we regret that we are unable to provide individual feedback to all candidates. If you do not hear back from us within 4 weeks of your application, please assume that you have not been successful on this occasion. We genuinely appreciate your interest and wish you the best in your job search.

Commitment to Equality and Accessibility:

At MLabs, we are committed to offer equal opportunities to all candidates. We ensure no discrimination, accessible job adverts, and providing information in accessible formats. Our goal is to foster a diverse, inclusive workplace with equal opportunities for all. If you need any reasonable adjustments during any part of the hiring process or you would like to see the job-advert in an accessible format please let us know at the earliest opportunity by emailing human-resources@mlabs.city.

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