Full-Stack Engineer

About Tessl

At Tessl, we believe AI will fundamentally change the way software is created, but we’re not just another AI code generation tool. We’re reimagining the entire software creation process to be truly AI Native, enabling breakthrough innovations that redefine not only how code is generated, but how software is designed, maintained and evolved.
We’re a Series A startup based in London, founded by Guy Podjarny (who previously founded Snyk) and backed by Index, Accel, GV & boldstart.
As an early member of our team, you’ll have the unique opportunity to shape the future of software development and make a lasting impact on the industry.

Overview of role

Join our User Journeys team to build real-time AI Native workflows, tooling, and interfaces that will reshape how developers create and maintain software.
As a Full Stack Engineer, you’ll thrive on variety: from refining intuitive user interactions in our Tiptap-based editor to developing CLI tools and IDE extensions that empower developers to interact seamlessly with Tessl.
You’ll report to Joe Holdcroft and collaborate closely with product, design, and the wider Engineering team to bring AI Native development to life in a fast-paced, high-autonomy 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 some of the things you could be doing:

• Spin up a proof of concept to showcase an innovative idea you’ve been thinking about
• Pair with a designer to fine-tune interactions in our UI, making the user experience more intuitive and slick
• Integrate a third-party service, for example for notifications, so we can stay focused on Tessl’s core capabilities
• Collaborate with other teams to plan an architecture that supports real-time streaming and collaboration across the platform
• Establish an end-to-end testing strategy to increase our confidence when deploying new features to production
• Author a decision document to articulate your technical vision for a new product capability you’ll be leading, sharing it with the wider engineering team for feedback and alignment

What we’re looking for

Essential

• Proven experience (often 6+ years) building complex products in diverse teams and environments
• Expertise in React, with a deep understanding of its core concepts
• Track record of building Node.js services, including designing and scaling APIs in production environments
• Comfortable with fast-paced, high-autonomy environments: you’ve ideally thrived in an early-stage startup before
• Deeply curious about AI, and excited to experiment, learn, and harness its potential to transform software engineering

Nice to have

• Background in AI products or developer tools
• Real-time collaboration experience, especially with CRDTs (e.g., Yjs)
• Familiarity with block-based WYSIWYG editors like Tiptap or ProseMirror
• Experience building and scaling REST APIs, particularly those conforming to JSON:API
• Production experience running Remix or other SSR React frameworks
• Strong UX and design sense: capable of crafting polished interfaces with minimal design input
• Familiarity building IDE extensions or CLI tools
• Comfortable working on infrastructure (e.g., setting up CI pipelines, navigating Kubernetes)

Salary and benefits

We offer a competitive salary that reflects your skills and experience, along with an equity package aligned with our early-stage growth.
Our benefits portfolio is continually evolving, and we currently provide health insurance with Aviva that extends to partners and dependents.
Our office, just a short walk from King’s Cross station, is pet-friendly, and we regularly host team socials, lunches, drinks and off-sites.
We’re a hybrid workplace with primary in-office days on Monday, Tuesday, and Thursday.

Application process

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

• Introductory call with Joe, your potential manager
  A relaxed chat to learn about your background, interests, and career goals. We’ll also share more about the role, Tessl’s vision, and answer any questions you have.

• Take-home exercise
  You’ll receive a practical challenge based on real scenarios you might tackle at Tessl: an opportunity to showcase your approach to problem-solving on your own schedule.

• On-site technical session
  You’ll pair with two of our founding engineers to build on your take-home exercise. This session simulates working together on real problems and allows us to explore your technical expertise more deeply.

• Culture conversation with Petra, our People Lead
  A two-way dialogue about our values, team dynamic, and your motivations. Feel free to ask about life at Tessl, growth opportunities, or anything else you’re curious about.

• Leadership discussion with Guy (CEO) or Ben (Head of Product)
  Our final stage focuses on strategic alignment and long-term vision. You’ll learn more about Tessl’s roadmap and how you could contribute to our mission.

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.