Full Stack Engineer / Technical Lead B2B SaaS

Company: Client Server
Apply for the Full Stack Engineer / Technical Lead B2B SaaS
Location: London
Job Description:

Overview

As a Full Stack Engineer / Technical Lead, you will shape the technical strategy and architecture for Developer Ecosystems, guiding API and SDK design for scalable, usable tooling. You’ll lead cross-team initiatives to expand client libraries, oversee the full lifecycle from design to release, and mentor engineers while engaging with external contributors and the developer community. The role combines hands-on coding with leadership, influencing product direction and technical standards. This is a chance to influence how developers interact with a high-scale real-time platform.

Pay / Benefits

  • EMI share option scheme
  • 28 days annual leave
  • Enhanced maternity and parental leave packages
  • Personal learning and development budget (1000 p/a + 5% time to work on your own projects)
  • BUPA Health Insurance + dental costs + mental health and wellness
  • Pension, Life Assurance, Income Protection

Responsibilities

  • Define and drive the technical strategy and architecture for Developer Ecosystems (iOS, Web, Infra/Automation)
  • Establish and enforce API and SDK design best practices for consistency and scalability
  • Lead complex, cross-team initiatives to expand client libraries
  • Oversee full development lifecycle from design to release, maintenance and evolution
  • Mentor junior engineers, review contributions, raise technical standards
  • Guide external contributors and open-source collaboration
  • Act as a main interface with the developer community and incorporate feedback into product direction

Key requirements

  • Senior software engineer with experience building developer tooling and APIs
  • Strong hands-on experience with Ruby, TypeScript and React
  • Experience in a product-focused B2B SaaS environment
  • Track record of making technical decisions that drive projects and raise the bar
  • Comfort with AI tools such as Claude and Cursor and understanding of their use to optimise processes
  • Customer and product-focused mindset
  • Collaborative and pragmatic with mentoring experience
  • Solid CS fundamentals (OOP, Data Structures, Design Patterns)
  • collaborative
  • pragmatic
  • customer-focused
  • Ruby
  • TypeScript
  • React

Posted: September 14th, 2026