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 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.

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…