Member of Technical Staff - Software Engineer

AI is transforming how software is built, and at Tessl, we're building the infrastructure for what comes next.

We're developing a platform that enables engineering teams to build and run AI-powered software factories, where coding agents take on real development work, from picking up engineering tickets to implementing changes and creating pull requests.

By combining structured context, reusable agent skills, automated workflows and evaluations, we're making AI-powered development more reliable, repeatable and scalable, while keeping humans in control. We're tackling some of the biggest challenges in autonomous software development, from code quality and security to helping organisations confidently adopt AI agents at scale.

Founded by Guy Podjarny, previously founder of Snyk, Tessl is a fast-growing Series A startup backed by over $100 million in funding from investors including Index Ventures, Accel, GV and Boldstart.

Joining Tessl means helping define an entirely new category of technology, solving ambitious technical challenges and shaping the future of software development.

OVERVIEW OF THE 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!)

Application Process

Here’s an outline of what you can expect during our interview process:

1. Intro Call

2. Hiring Manager Chat

3. Take-Home Exercise

4. On-site Technical Session

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 want Tessl to be a place where you can do meaningful work, keep learning and enjoy being part of the team. Alongside competitive compensation, we offer benefits designed to support you both inside and outside work.

What we offer

• Competitive compensation and equity: Market-benchmarked salaries and EMI share options.

• Time off: 25 days of annual leave, plus UK public holidays, and two paid volunteering days each year.

• Private healthcare: Vitality medical insurance, including dental, optical and mental health support, with cover included for partners and dependants.

• Pension: A 5% employer pension matched contribution through Smart Pension.

• Life assurance: Company-paid life insurance with MetLife providing cover of four times your annual salary.

• Family Leave: We offer enhanced Maternity, Parental and Adoption Leave from day one to support you and your growing family.

• Learning and development: We support opportunities to continue developing your skills with a £1,000 per year to spend.

• Commuting benefits: Financial support for eligible team members commuting from outside Greater London, plus a Cycle to Work scheme.

• Summer & winter offsites: Twice a year, we bring the whole Tessl team together for a week-long offsite. It's a chance to step away from our usual routines, collaborate on big ideas, build stronger relationships and enjoy shared experiences together. And of course, we have a lot of fun along the way!

Our London HQ

Our office is in the heart of King's Cross, surrounded by London's growing AI and technology community.

We work together in person on Mondays, Tuesdays and Thursdays, giving us time to collaborate, exchange ideas and build relationships. You'll also enjoy catered lunches (Tuesday & Thursday), plenty of office snacks, regular team lunches and socials, plus a pet-friendly workplace.

How we work

Our operating principles shape how we collaborate and make decisions. We move quickly and learn by doing, build on ideas before challenging them, get stuck in wherever we can help, and give people real ownership. We encourage thoughtful debate, curiosity and a willingness to try things that haven't been done before. Read our five operating principles.

We're AI native

AI isn't just what we're building - it's central to how we work every day, across every function. We actively use AI to improve how we work, solve problems and challenge traditional ways of doing things.

You don't need to be an AI expert to thrive at Tessl, but you do need curiosity, an appetite for experimentation and a willingness to embrace new ways of working. We expect everyone to use AI regularly, invest time in learning how to get the most from it and keep experimenting when something doesn't work the first time, rather than defaulting to manual approaches.

We're also big believers in sharing what we learn. We encourage transparency about how we're using AI, what's working, what isn't and how we can help each other improve. Being AI native doesn't mean removing human judgement, it means using AI thoughtfully, while taking ownership of the quality and outcomes of our work.

Everyone is welcome at Tessl

We're committed to building an inclusive environment where people from different backgrounds, experiences and perspectives can thrive.

We particularly welcome applications from people who are underrepresented in technology. If you're excited about the opportunity but don't meet every requirement, we'd still encourage you to apply.

If you need any adjustments or additional support during the recruitment process, please let us know. We're happy to work with you to make the process accessible and comfortable.

Come build with us

We're moving fast, experimenting boldly and figuring things out as we go. There's plenty to build, lots to learn and real opportunities to make your mark.

If you're excited by big ideas, enjoy getting stuck in and want to be part of something from the ground up, we'd love to hear from you!