Senior Software Engineer

Toolbx; London; On-site; USD 175,000 - 200,000; Full time

Job summary

A startup focused on AI solutions is seeking a Senior Software Engineer in London. You will design and build scalable systems using Node.js and TypeScript, collaborate with a small team to drive architectural decisions and use AI tools. Competitive compensation offers $175,000 to $200,000 plus equity, with a flexible, people-first culture.

Benefits

Health Coverage

Discretionary Time Off

Workspace Setup Support

Autonomy & Ownership

Qualifications

• 5+ years of full-stack development experience.
• Deep expertise in Node.js and TypeScript; React experience is a plus.
• Experience with AWS services and cloud-native infrastructure.

Responsibilities

• Build core features from conception to production release.
• Develop robust APIs and backend logic using Node.js on AWS.
• Use AI tools to enhance development velocity and code quality.

Skills

Node.js

TypeScript

AWS

Full-stack development

AI tools

Tools

React

AWS Amplify

Job description

About our client

heyLibby is a seed-stage startup on a mission to give every small-to-midsize fitness and wellness business a world-class AI team member. It was co-founded by Spencer Rascoff, the former CEO of Zillow and current CEO of Match Group. Its AI works seamlessly across phone, email, text, and chat to help businesses manage their communications efficiently. The team moves fast, prioritizes impact, and works closely with top industry experts. They ship fast, learn fast, and measure themselves by the tangible impact delivered to customers.

About the role

The company is looking for a highly skilled and experienced Senior Software Engineer with the ability to architect, design, and build and with expertise in Node.js, TypeScript, and AWS. This person will be a critical part of the small, high-impact team, architecting and building scalable systems while making quick and pragmatic decisions. They value engineers who can think creatively, ship fast, and build practical solutions that drive real business value. The team also uses AI throughout all daily tasks and is looking for engineers who can use the latest AI technologies to accelerate development.

Why this role matters

The company is looking for a senior engineer to join the small but mighty team and own core pieces of the product stack. This is a high-impact role where the person will shape how backend and frontend systems evolve to support a rapidly growing customer base.

They will help scale Node.js services, and drive architectural decisions across the board. They will also use AI tools to accelerate development and optimize delivery—everything from code generation to testing and beyond.

What You’ll Do

• Build Core Features End-to-End
• Design and deliver user-facing and backend functionality, from conception to production release.
• Scale Backend Services
• Develop robust APIs and backend logic using Node.js on AWS, with a focus on performance and reliability.
• Shape System Architecture
• Select design patterns, lead technical decisions, and implement scalable, maintainable systems.
• Apply AI in Development Workflows
• Use the latest LLM tools and frameworks to enhance development velocity and code quality.
• Own the Frontend Experience
• Take charge of the frontend, using React + TypeScript or tools like lovable.ai to ship smooth, responsive interfaces that customers love.
• Collaborate Cross-Functionally
• Work closely with founders, engineers, and AI specialists to iterate quickly and align on product direction.

What They’re Looking For

Must-Have Experience

• 5+ years of full-stack development experience
• Deep expertise in Node.js and TypeScript; React experience is a plus
• Experience with AWS services and cloud-native infrastructure
• Strong architectural instincts; confident designing scalable, maintainable systems
• Ability to leverage AI tools for coding, testing, and optimization
• Comfort with fast-paced environments and shipping iteratively
• Strong communication and a team-first mindset
• A ‘get-it-done’ attitude and a bias toward execution over perfection

Bonus Points

• Experience with AWS Amplify
• Prior startup or small team experience
• Familiarity with automated testing and CI/CD pipelines
• Exposure to identity frameworks (OIDC, OAuth, etc.)
• Experience with IAM and access control strategies

How They Work & What the Role Offers

• Competitive Comp – $175,000 to $200,000 + meaningful equity
• Health Coverage – Full medical, dental, and vision benefits are offered
• Discretionary Time Off – Trust is placed in the individual to balance work and rest
• Workspace Setup Support – Gear needed to be productive is covered
• Autonomy & Ownership – The engineer is trusted to drive decisions
• Velocity – Weekly releases, minimal ceremony, rapid experimentation
• Impact – Code will be on the critical path for every customer interaction
• Flexible, People-First Culture – The team works hard but protects family and personal time

Ready to build AI that works like magic and ships cool new features frequently? Apply now and help redefine how small businesses connect with their customers.