Head of Engineering

Tessl

Tessl is a fast-growing Series A startup based in London, founded by Guy Podjarny. We’ve raised over $100M from world-class investors including Index Ventures, Accel, GV, and Boldstart, and in 2025 we were ranked #2 in Sifted EU’s B2B SaaS Rising 100 and #20 in Sifted's AI 100. At Tessl, we are building the context layer for AI coding agents, and a platform for AI-native software development. As an early member of the team, you’ll help shape how we build, scale and support a company operating at the edge of AI and software development. OVERVIEW OF THE ROLE We're hiring a Research Engineer to join our AI Research (AIR) team. You'll work on the components that make the outer loop real: how agent harnesses orchestrate model behaviour, how we evaluate what's actually working, how pipelines turn production traces into the next round of improvement, and how we diagnose the failure modes that matter to real users. These aren't four separate workstreams — they're parts of one system, and we want people who see them that way. We expect you to sit close to customers — joining calls, watching sessions, reading traces — and to let real workflows shape your research priorities. You'll have meaningful autonomy and the resources to run substantial experiments where the bar for success is shipped impact. You'll report to our AI Research Lead, and collaborate closely with engineering, product, and design. WHAT WE'RE LOOKING FOR We're explicitly building coverage across four skill areas. You don't need to be strong in all of them — but you should bring depth in at least one: * Agent harness and orchestration design — how tools, context, and control flow combine to make a useful agent. * Agentic eval methodology — task and repo-level evals, dataset curation, the craft of measuring what actually matters. * Outer-loop and pipeline thinking — feedback loops, training-data flywheels, bandit-style optimisation, anything that goes beyond a single agent session. * Failure-mode analysis — instrumenting agents, reading traces at volume, surfacing patterns engineering can act on. ESSENTIAL * 4+ years shipping AI/ML products in a startup or applied industry setting, with recent hands-on experience with LLMs and agentic systems. * Demonstrated depth in at least one of the four skill areas above. * Strong product and customer instincts: comfort joining customer calls, watching session recordings, and letting real workflows shape what you work on. * Sharp evaluation judgement: benchmarks where they exist, vibes and quick prototypes where they don't, and the taste to know which is appropriate. * Experience building datasets for evaluation or training, including the pipeline work that goes with it. * Deeply curious about agents and excited about reshaping how software is built. NICE TO HAVE * A Masters or PhD in a relevant computational field. * Direct experience with coding agents or code-generation systems. * Background in RL, bandits, or other outer-loop optimisation frameworks applied to LLMs. * Experience building synthetic data, dataset infrastructure, or internal tooling that other engineers actually used. * A project you can show us (GitHub links welcome) and a thoughtful answer to "Why Tessl?" WHAT YOU'LL DO No two weeks will look the same. A flavour: * Sit in on a customer session, understand how their agents are failing, design an eval that captures it, and drive a fix through to shipped improvement. * Close a piece of the outer loop end to end: production signal in, dataset out, eval scored, harness change shipped, metric moved. * Own a slice of our eval infrastructure: dataset curation, harness configuration, runner, analysis, and the comms back to engineering. * Prototype a new harness or context configuration and measure whether it actually moves the needle on real customer tasks. * Dig through pages of agent traces, build the tooling you need to make sense of them, and brief the team on what you found. * Partner with product and engineering on near-term shipping problems by bringing research rigour. * Pull a recent paper apart, work out what's actually transferable to our platform, and turn it into a concrete experiment. YOU’LL BE SUCCESSFUL IF… In your first 3 months, you might have shipped a new eval suite for a real customer workflow, improved an agent harness based on trace analysis, or built a pipeline that turns production failures into reusable test cases. SALARY AND BENEFITS Competitive salary commensurate with experience. Health insurance extending to partners and dependents, pension contributions, and the rest of what you'd expect. Our office is a couple of minutes from King's Cross — pet friendly, with regular team lunches, drinks, and socials. We're hybrid, with Monday, Tuesday, and Thursday as the primary in-office days. APPLICATION PROCESS * Intro call to understand "Why Tessl?" and to tell you a bit about us. * A call with our AI Research Lead to understand your ways of working and how you use agents. * A 4 hour technical take-home exercise extending our one-shot implementation. * A half-day on-site session including whiteboarding and hands-on activities. * Leadership chats with our Head of People, Head of Engineering and CEO. We care deeply about the warm, inclusive environment we’re building at Tessl and we value diversity – we welcome applications from those typically underrepresented in tech. If you like the sound of this role but are not totally sure whether you’re the right person, do apply anyway! LEARN HOW WE THINK AND WORK * On Tessl, The AI Native Development Startup * Announcing skills on Tessl: the package manager for agent skills * Podcast Episode: The End of Fragmented Agent Context, Guy Podjarny Tessl CEO

Sanity

At Sanity.io, we’re building the future of AI-powered Content Operations. Our AI Content Operating System gives teams the freedom to model, create, and automate content the way their business works, accelerating digital development and supercharging content operations efficiency. Companies like SKIMS, Figma, Riot Games, Anthropic, COMPLEX, Nordstrom, and Morningbrew are using Sanity to power and automate their content operations. Sanity Content Agent is where AI meets structured content - an intelligent assistant that deeply understands each customer's content model, follows references like an experienced team member, and combines web research with internal content knowledge in a single conversation. Sanity is uniquely positioned for this moment: we already have a scaled Content Lake holding our customers' structured content, which becomes rich context that generic AI tools simply can't match. Your team will push the boundaries of what's possible when AI truly understands content: auditing thousands of documents in seconds, surfacing inconsistencies before customers do, and generating perfectly structured documents that respect complex validation rules. With a strong and growing team of 4 engineers and room to scale as the product grows, you'll shape the AI capabilities that turn hours of content work into minutes. You'll balance the technical challenges of LLM integration and agentic workflows with the product sensibility to make AI that content teams actually trust. Learn more about the team’s products here, here and here. This role requires a good grasp of web fundamentals and toolchains and an understanding of how the modern web works. We also seek someone with strong organizational and planning skills. Leading an engineering team at Sanity is about working with the product manager and designer of the team, to own the strategy, roadmap, and execution. This is achieved by working with great people and creating an environment where your team can shine. As a senior engineering management leader, you’ll be responsible for growing a strong and engaged team to meet these challenges. WHAT YOU WOULD DO: * Helping a team of talented engineers to organize and prioritize their work for the highest impact. * Balance technical excellence with shipping velocity in a fast-moving environment. * Experience working at a product/SaaS company. * Champion developer experience while building for non-technical content creators. * Influencing the direction of both Sanity and of modern web development and content operations. * Work closely with the Head of Engineering, along with leadership in product management and design, to facilitate teamwork and establish processes that can scale as we do. * Supporting the growth and development of your team and team members. ABOUT YOU: * Based in London, UK, or Oslo, Norway, and able to work at least 2-3 days per week in the office. * 1+ years of engineering management experience & 4+ years of engineering experience, ideally in developer tools or content platforms * Strong technical background in TypeScript/JavaScript and modern web technologies * Ability to navigate ambiguity and drive clarity in product direction * Working knowledge of prompt engineering, evaluation frameworks, and techniques for improving model reliability * Understanding of embedding models, vector search, and how to ground AI outputs in structured data * Ability to distinguish AI capabilities that genuinely solve user problems from those that just demo well * Track record of shipping user-facing products at scale * Experience leading teams building complex, extensible applications * An ability to understand software architecture design considerations Not sure you’re exactly what we’re looking for in this role? Apply anyway! WHAT WE CAN OFFER: * A highly-skilled, inspiring, and supportive team * Positive, flexible, and trust-based work environment that encourages long-term professional and personal growth * A global, multi-culturally diverse group of colleagues and customers * Comprehensive health plans and perks * A healthy work-life balance that accommodates individual and family needs * Competitive salary and stock options program WHO WE ARE: Sanity.io is a modern, flexible content operating system that replaces rigid legacy content management systems. One of our big differentiators is treating content as data so that it can be stored in a single source of truth, but seamlessly adapted and personalized for any channel without extra effort. Forward-thinking companies choose Sanity because they can create tailored content authoring experiences, customized workflows, and content models that reflect their business. Sanity recently raised a $85m Series C led by GP Bullhound and is also backed by leading investors like ICONIQ Growth, Threshold Ventures, Heavybit and Shopify, as well as founders of companies like Vercel, WPEngine, Twitter, Mux, Netlify and Heroku. This funding round has put Sanity in a strong position for accelerated growth in the coming years. You can only build a great company with a great culture. Sanity is a 200+ person company with highly committed and ambitious people. We are pioneers, we exist for our customers, we are hel ved, and we love type two fun! Read more about our values here! Sanity.io pledges to be an organization that reflects the globally diverse audience that our product serves. We believe that in addition to hiring the best talent, a diversity of perspectives, ideas, and cultures leads to the creation of better products and services. We are committed to equal employment opportunity regardless of race, color, ancestry, religion, sex, national origin, sexual orientation, age, citizenship, marital status, disability, or gender identity.

Ledgy

At Ledgy, we’re on a mission to make Europe a powerhouse of entrepreneurship by building a modern, tech-driven equity management and financial reporting platform for private and public companies. In 2026, we aim to be the leading provider for European IPOs and reporting for share-based payments. We are a value-based company with a core focus on being humble, transparent, ambitious and impactful, all in order to delivery the best experience for our customers and end users. We are proud to partner with some of the world’s leading investors. New Enterprise Associates led our $22m Series B round in 2022, with Philip Chopin joining Sequoia’s Luciana Lixandru on our board. We were founded in Switzerland in 2017 and today we operate globally from offices in Zurich and London. We encourage diversity and are an international team coming from 26 different countries and speaking 25 different languages.   About the Role As a hands-on Engineering Manager of one of our feature teams at Ledgy, you'll lead the engineers who build the features that help companies offer, manage, and communicate compensation and savings vehicles: from equity plans to pensions, carry, and beyond. Your team works on the products employees and companies use to make sense of complex compensation structures. This is a good fit if you find it meaningful to work on features that are financially significant to the people using them, as getting compensation right matters. The work is domain-rich: these structures are complex, high-stakes, and varied. You'll report to the Head of Engineering and play a key role in expanding Ledgy's product coverage as companies increasingly look to offer diverse forms of compensation.   You'll Thrive in This Role If You * Have 2+ years in Engineering Management and 6+ years as a Software Engineer, with meaningful time in product-focused or domain-heavy roles * Are energised by features that have a direct, visible impact on end users — the things employees actually see and interact with * Care deeply about correctness in domains where getting things wrong has real financial consequences * Are comfortable with evolving scope — compensation takes many forms, and the product will grow to reflect that * Actively use AI tools to multiply your output and are excited to help your team do the same — you see AI as a core part of how great engineering gets done today * Love developing people and creating an environment where engineers can do their best work * Want to stay hands-on — you're comfortable diving into the codebase, reviewing PRs with concrete feedback, and shipping yourself What You'll Own * Team Leadership: Setting technical direction for the team, running 1:1s and performance conversations, and supporting engineers in their growth. * AI-Augmented Engineering: Modelling and promoting effective use of AI tools across your team — from coding assistants to automated workflows. You'll help engineers develop good instincts for where AI accelerates work and where human judgment matters most. * Compensation & Savings Features: The product surface covering a range of compensation and savings vehicles — equity plans, pensions, carry, and more. Your team builds the logic and UX that makes these products usable for both companies and their employees. * Employee-Facing Experience: Ensuring the features your team builds are not just correct, but clear and accessible to employees navigating complex compensation structures. * Domain Breadth: As Ledgy expands into new compensation types, your team will be at the frontier, building the models and product experiences that bring them to life. Our tech stack: * Language: TypeScript * Frontend: React, Tailwind CSS, tRPC * Backend: tRPC, Node.js, MongoDB, Temporal * Infrastructure: Docker, GitHub Actions, GCP, Terraform Cloud, Kubernetes What Your Journey Could Look Like First 30 Days * Build relationships with your direct reports and develop a solid understanding of the compensation domain, including what we support today and where we're headed * Get hands-on with the codebase — review PRs and understand how the product models compensation and plan logic * Meet PD leadership: CTO, Head of Engineering, Head of Product, and the other EMs * Understand how your team's domain intersects with the rest of the platform First 3 Months * Own the team's delivery rhythm: roadmap reviews, sprint health, and unblocking engineers * Identify and begin addressing the most complex or fragile areas of the domain * Establish regular 1:1s and begin meaningful coaching conversations with your reports * Partner with PM and Design on the roadmap for expanding compensation coverage 6–12 Months * Be recognised as the technical leader for compensation and savings features at Ledgy * Deliver measurable improvements to product quality, coverage, or the employee experience * Lead performance reviews and meaningful career development conversations * Be a trusted partner to product and engineering leadership on compensation strategy The Interview Process 1. Getting to know you (30 min): Meet with someone from our people team to talk about your experience and to answer questions about the role 2. Live Coding (60 min): A problem-solving session (without AI) using your preferred language and IDE 3. System Design (60 min): Walk us through an architecture you've significantly contributed to — we'll explore domain modelling and product complexity based on your experience 4. Mock 1:1 (45 min): A mock coaching conversation with one of our engineers to see how you approach people management and development 5. Culture & Vision (30 min): Meet one of our founders to discuss Ledgy's mission and how you think about making compensation and savings products work for everyone 6. Offer 🎉 Being part of Ledgy means: * Recharge and re-energize with flexible working hours, 25 days of vacation, and up to 40 days of remote work from outside your home country. * We make space for your own professional development, with a generous yearly learning & development budget. * This role will receive a competitive salary + benefits + equity. All salaries are aligned with competitively benchmarked ranges based on work location and levelling. * For candidates based in London or Zurich we use a hybrid work model of 2 days in the office per week.