Member of Technical Staff - Software Engineer

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 this year we were ranked #2 in Sifted EU’s B2B SaaS Rising 100 and #20 in Sifted's AI 100.

At Tessl, we believe AI is transforming software development. AI Native Developers will define features, architecture, and workflows in specs, not code, guiding the work of AI agents. We’re building the pioneering platform for this new paradigm and leading the developer movement and ecosystem around it.

Joining Tessl means becoming an early team member with the opportunity to shape the future of how software is created and maintained.

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.

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

• 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

• Background in AI products or developer tools
• Experience in rapid prototyping environments
• Programming polyglot experienced in several languages of different paradigms (e.g.: JavaScript/Type Script, 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 (Git Hub links welcome!)

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…