Member of Technical Staff (Software)

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 ROLE Join our engineering team to build real-time AI Native workflows, tooling, and interfaces that will reshape how developers create and maintain software. As a Software Engineer, you’ll be versatile and independent, excited to work with cutting-edge AI tools to build great products. We move quickly, but with purpose - balancing speed with collaboration and thoughtful execution. You’ll collaborate closely with product, design, and the wider Engineering team to bring AI Native development to life in a fast-paced, high-trust environment. WHAT YOU’LL DO No two days will be the same at Tessl! You’ll have a high level of autonomy and be able to make decisions based on what you believe will help you deliver the most success. Here’s an insight into just a few of the things you would be doing: * Design and implement new functionality that you discussed and reviewed with the product team * Spin up a proof of concept to showcase an innovative idea you’ve been thinking about * Rapidly prototype a new language integration for our code generation pipeline, then develop a plan for a scalable implementation. * Pair with a designer to fine-tune interactions in the UI, CLI or existing AI coding agents, making the user experience more intuitive and slick * Integrate a third-party service, e.g. for notifications, so we can focus our own cycles on Tessl’s core capabilities * Collaborate with other teams to plan an architecture that supports collaboration across the platform * Establish an end-to-end testing strategy to increase our confidence when deploying new features to production * Share your technical vision for a new product capability you’ll be leading with the wider engineering team for feedback and alignment WHAT WE’RE LOOKING FOR ESSENTIAL * Proven experience (typically 5+ years or equivalent) as a Software Engineer. You care about code modularity, structure and aesthetics and have firsthand experience in how software is built across teams and environments * Equally comfortable contributing to a mature codebase with strict CI criteria or hacking up a quick prototype to prove/disprove an assumption * Proven experience leveraging the best AI coding tools and agents to accelerate and enhance your own work and efficiency * Comfortable with fast-paced, high-autonomy environments: you’ve ideally thrived in an early-stage startup before * You have demonstrated usage of AI tools in your day-to-day work, and be excited about experimenting, learning, and harnessing the potential of new AI tools and approaches to transform software engineering NICE TO HAVE * Background in AI products or developer tools * Experience in rapid prototyping environments * Programming polyglot experienced in several languages of different paradigms (e.g.: JavaScript/TypeScript, Python, C or C++, Haskell, etc.) * Experience collaborating with AI researchers and bridging between research-focused and engineering-focused teams * Experience building & scaling REST APIs, particularly those conforming to JSON:API * Comfortable working on infrastructure (e.g., setting up CI pipelines, navigating Kubernetes) * If you have a personal or open-source project you’d like to share, we’d love to see it (GitHub links welcome!) 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 have 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 based on experience and skills, 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 Here’s an outline of what you can expect during our interview process: 1. Introductory Call 2. Take-Home Exercise 3. On-site Technical Session 4. Culture Conversation 5. Leadership Discussion Throughout the process, if you have any specific requirements or need adjustments, please let us know: we’re happy to accommodate. 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

Jua

OVERVIEW Physical AI, a real model of the world, is the next trillion dollar opportunity and a foundational pillar for energy, robotics and superintelligence. At Jua we are building it now. Our models already run on four continents and help power the energy buildout needed to support ever larger intelligence. We are assembling a world-class team of researchers and entrepreneurial minds to turn this model into reality at global scale. If you want the opportunity of your life, come build physical AI with us. WHAT WE’RE LOOKING FOR We’re redefining earth simulation with machine learning, building a system that outperforms traditional models in speed, precision, and accuracy. Our team moves fast, leveraging a versatile tech stack and state-of-the-art cloud infrastructure to maximize performance and efficiency. We believe in using the right tools for the job, combining robust web technologies, advanced ML frameworks, and powerful numerical computing. With a focus on type-safe programming and infrastructure-as-code, we ensure scalability without excess complexity. As a Software Engineer, you’ll help shape our backend systems, pipelines, and cloud infrastructure. You’ll thrive in ambiguity, iterate fast, and turn ideas into working prototypes. If you have a hacker’s mindset, love building from scratch, and excel in lean, high-impact environments, we’d love to hear from you. Location: Although we are a global team, it is a requirement that applicants are currently based in Zurich, Switzerland, working on a Hybrid working model. OUR TECH STACK * Core Languages: Python is our go-to for backend development, data pipelines, and ML integration. Deep experience with modern Python is a must. We also have a light dusting of rust where performance is critical. * Data & Geospatial Libraries: We rely heavily on libraries like Xarray, Pandas, and Polars for numerical computing and geospatial data processing. Familiarity with these tools is a big plus. * Cloud & Infrastructure: We use a mix of multi-cloud (GCP, AWS, Cloudflare) and bare metal infrastructure, with tools like Pulumi for infrastructure-as-code. * ML Frameworks: We leverage popular ML libraries and frameworks to build and deploy models efficiently * Other Tools: While Python is our primary language, we believe in using the right tool for the job. You’ll have the freedom to introduce new technologies when they make sense. RESPONSIBILITIES AND TASKS * Build scalable systems: Design, develop, and deploy backend pipelines, services, and cloud infrastructure with a focus on speed, scalability, and pragmatism. You’ll work across the stack—from backend services to occasional front-end integrations and CI/CD pipelines—in a mixed multi-cloud and bare metal environment. * Help to shape our architecture and roadmap: Play a key role in defining how we build and scale. As an early senior engineer, you’ll influence technical strategy, optimize system design, and ensure long-term maintainability while moving fast. * Bring ML models to production: Work closely with ML engineers to deploy models that power real-world decision-making, ensuring performance, reliability, and usability for customers, including power traders. * Identify and tackle technical challenges: Address performance bottlenecks, refactor critical systems, and strike the right balance between rapid iteration and long-term stability. * Prototype and iterate quickly: Move fast, test ideas, and refine approaches with short feedback cycles to drive continuous improvement. NEED-TO-HAVE * Bachelor’s degree (or higher) in Computer Science or a related field. * 5+ years of experience in a Software Engineering role. * Strong experience with modern Python in large-scale production systems. * Ability to make pragmatic, fast-paced decisions while managing technical debt effectively. * Proactive in identifying problems, performance bottlenecks, and areas for improvement. * Nice-to-have: Exposure to Data Engineering or related experience. AT THE END OF YOUR FIRST 30 DAYS, YOU WILL HAVE * Deployed code to production: Created a pull request, merged it, and deployed iteratively, optimizing for progress rather than perfection. * Gained deep product immersion: Understood the “what” and “why” of the product, contributed to discussions, formed opinions and comfortably expressed them, and actively participated in team retros. * Worked independently on scoped components: Delivered isolated, limited-scope features, addressed feedback, and deployed quickly with minimal supervision, making confident decisions. * Engaged with Jua’s principles and values: Collaborated across teams and built independent working relationships. ABOUT YOU * You work in alignment with our operating principles. These principles guide how we make decisions, collaborate, and build at Jua. You embody them in your work, continuously evolving as we evolve, and integrating them into everything you do. * You take initiative and drive action. You proactively identify challenges and opportunities, taking ownership without waiting for direction. You thrive in an environment where autonomy and action lead to impactful results. Rather than waiting for permission, you step forward, solve problems, and drive meaningful change. * You are adaptable and resourceful. You’re comfortable navigating ambiguity, making data-informed decisions, and iterating as you go. Limited resources don’t slow you down—they inspire creative problem-solving. Whether working with evolving technologies or shifting priorities, you find a way forward and deliver exceptional outcomes. * You thrive in a fast-paced team. We work extremely hard to be the fastest in our field, speed and excellence are non-negotiable. You’ll be surrounded by overperformers in every discipline, and we expect the same from you. If you don’t consider yourself among the best in your field, Jua likely isn’t the right fit. * Our feedback culture is radically transparent and truth-seeking. This can be intense if you’re more used to comfort than candor, but for those who thrive on challenge, it’s an environment where you’ll grow fast and do the best work of your career. WHAT’S IN IT FOR YOU * Work on groundbreaking technology: Be at the forefront of weather forecasting and machine learning, contributing to innovations that push the boundaries of what’s possible. * Collaborative, remote-first culture: Join a dynamic, supportive team where your ideas matter, and work remotely with flexibility that fits your lifestyle. * Shape the future: Play a pivotal role in growing and evolving the backend of a product that’s rapidly advancing in a fast-paced environment. * Impactful industry: Work in the energy trading sector, using AI to drive real-world change and help shape the future of energy markets. Please note: We prioritise your answers to the application questions over your CV, so we encourage you to complete them as thoughtfully and thoroughly as possible. At Jua, we foster a performance culture and value people who embody our beliefs of service and adventure. We prioritize agility, operating at the highest clock speed to adapt quickly to change. We innovate on behalf of our users and leverage data supremacy to maintain our competitive edge. Through clear communication and fact-based decision-making, we ensure alignment in our pursuit of excellence. With these principles, we aim to create a customer-focused, value-centric organization that sets new standards in the industry. We value the unique perspectives that each individual brings to the table and believe that embracing diverse backgrounds and experiences enriches our collective journey towards growth and success.

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