Tessl

Tessl is a fast-growing Series A startup based in London, founded by Guy Podjarny, who previously founded Snyk. We’ve raised more than $100 million from world-class investors, including Index Ventures, Accel, GV and Boldstart. In 2025, Tessl ranked #2 in Sifted’s B2B SaaS Rising 100 and #20 in its AI 100. We’re 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 and scale a company operating at the forefront of AI and software development. ABOUT THE ROLE We're looking for a Member of Product Staff — a senior, hands-on product manager who can own ambiguous, high-stakes problems end to end and help define how product is practised as the team grows. This is a generalist role. The patterns for how developers work with AI agents are still forming, and you'll have a direct hand in shaping them across the product — from the CLI and core platform to the new bets we'll place as we expand. Much of the work is 0-to-1: you'll shape product direction amid genuine ambiguity, translate fast-moving model and research breakthroughs into experiences developers trust, and decide what's worth building when there's no settled playbook. We also expect this person to be building a genuinely AI-native product practice: using the best available tools to think more clearly, move faster, and raise the quality of the work. We're not looking for someone who uses AI occasionally — we want someone actively developing how they work with it, and setting the standard for the team. WHAT YOU'LL WORK ON - Own product areas end to end. Take problems from early concept through discovery, definition, launch, and iteration — setting priorities for a cross-functional team and making the calls on what matters most. - Develop deep product sense for developer workflows. Spend real time with developers and engineering teams to understand how they think, where they struggle, and where AI creates the most leverage. Turn those observations into specific, well-reasoned product decisions. - Translate frontier capability into product. Partner closely with engineering and research to turn new model capabilities and agentic breakthroughs into reliable, high-value developer experiences. - Shape strategy, not just execute it. Bring a clear point of view to roadmap and direction. You'll be in the room for strategy conversations and expected to help shape outcomes, not just respond to decisions already made. - Lead through influence. Act as the connective tissue between engineering, design, research, GTM and leadership — and as a credible voice with customers. Keep a globally-minded, fast-moving team rowing in the same direction. - Maintain a high quality bar at speed. Ship quickly without losing rigour, and hold the line on quality and developer trust even when the product is changing fast. - Build an AI-native product process. Define which tools and workflows raise quality and pace, share what you learn, and help set how product gets done at Tessl. WHAT WE'RE LOOKING FOR - Experience: Roughly 6+ years in product management (or equivalent), with a track record of shipping real, technically demanding products end to end. Comfortable operating at a senior IC level with significant autonomy. - Product sense & judgment: Strong instincts for what to build and why, backed by good business judgment and the ability to reason clearly under ambiguity and incomplete information. - Technical fluency: A track record of building for technically sophisticated users — developers, engineers, or data professionals. You don't need to be an engineer, but you should be genuinely curious about how the systems you build for actually work, and able to partner with research and engineering at a technical level. - 0-to-1 instinct: Comfortable shaping direction where there's no settled product, market, or process. You're drawn to ambiguity rather than unsettled by it. - Collaboration & communication: Excellent communicator who can align and influence engineers, designers, researchers and leaders who think differently to you. Confident enough to hold a point of view, flexible enough to run with the best idea wherever it comes from. - Domain experience (a plus): Developer tools, AI/ML applications, or productivity infrastructure. Exposure to CLI tooling, agentic workflows, or evaluation systems is a genuine advantage. We don't have all the answers yet. This is a role where you'll help define new patterns, work at the edge of what's known, and shape how product is practised at a company still figuring things out in the best possible way. If that excites you, and you feel you'd be a strong fit even if you don't meet every criterion listed, we'd encourage you to apply. SALARY AND BENEFITS Office: Our brand new 10,000 sq. ft office is in the AI hub of Kings Cross, London. We have generous catering and regular social events such as team lunches, drinks and more. We require all staff to be in our London HQ at least 3 days a week on our anchor days of Monday, Tuesday and Thursday. Salary: We offer a competitive salary commensurate with experience and skills and employee share options, benchmarked against industry standards. Benefits: 25 days holiday, health insurance, including dental and vision, which extends to partners and dependents, as well as a company-matched pension. We also provide a commuting stipend for those who live outside London, and a cycle to work scheme. APPLICATION PROCESS 1. Screening call 2. Case study presentation (with the hiring panel) 3. Final round — cross-functional collaboration, leadership, and a hands-on PM workshop 4. Leadership Chat 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 https://www.tessl.io/blog/announcing-tessl-the-ai-native-development-startup - Announcing skills on Tessl: the package manager for agent skills https://tessl.io/blog/skills-are-software-and-they-need-a-lifecycle-introducing-skills-on-tessl/ - Podcast Episode: The End of Fragmented Agent Context, Guy Podjarny Tessl CEO https://youtu.be/ntkM-hRblfo

Tessl is a fast-growing Series A startup based in London, founded by Guy Podjarny, who previously founded Snyk. We’ve raised more than $100 million from world-class investors, including Index Ventures, Accel, GV and Boldstart. In 2025, Tessl ranked #2 in Sifted’s B2B SaaS Rising 100 and #20 in its AI 100. We’re 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 and scale a company operating at the forefront 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 https://www.tessl.io/blog/announcing-tessl-the-ai-native-development-startup - Announcing skills on Tessl: the package manager for agent skills https://tessl.io/blog/skills-are-software-and-they-need-a-lifecycle-introducing-skills-on-tessl/ - Podcast Episode: The End of Fragmented Agent Context, Guy Podjarny Tessl CEO https://youtu.be/ntkM-hRblfo