Full Stack Engineer / Technical Lead B2B Saas

Client Server; Greater London; Hybrid; GBP 100,000 - 130,000; Full time

Benefits offered by this job

Health Insurance

Pension

Life Insurance

BUPA Dental & Mental Health

Sabbatical after 5 years

Learning budget £1000 p/a + 5% time

Home-station setup

Gym subsidies

Cycle to work

Job summary

Client Server in London is seeking a Senior Full Stack Engineer/Technical Lead to own technical strategy and architecture for one or more developer ecosystems. You will guide API/SDK design, drive best practices, and lead cross-team initiatives to improve client libraries.

You will oversee the full development lifecycle, mentor junior engineers, review contributions, and coordinate with external contributors and the developer community to shape product direction.

Qualifications

• 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.
• Experience making technical decisions that drive projects.
• Comfort with AI tools such as Claude and Cursor.
• Customer- and product-focused mindset.
• Collaborative and pragmatic with mentoring experience.
• Strong CS fundamentals: OOP, data structures, design patterns.

Responsibilities

• Own technical strategy and architecture for one or more Developer Ecosystems (iOS, Web, Infra/Automation).
• Define and drive API and SDK design for usability and scalability.
• Lead cross-team initiatives to expand and improve client libraries.

Skills

Ruby

TypeScript

React

APIs

Mentoring

Leadership

Tools

Git

Cloud tooling

Job description

Full Stack Engineer / Technical Lead B2B SaaS Client Server London, England

Full Stack Engineer / Technical Lead (Ruby TypeScript React) London / Remote to £130k

Opportunity for a full stack technologist to join a highly regarded provider of serverless real-time infrastructure for the Internet that processes billions of messages a day and powers everything from live chat and VoIP calls to real-time pricing and stock availability for a multitude of services around the globe.

As a Full Stack Engineer / Technical Lead you'll own the technical strategy and architecture for one or more Developer Ecosystems (iOS, Web, Infra/Automation), define and drive best practices for API and SDK design, ensuring consistency, usability and scalability and lead complex, cross-team initiatives to expand and improve client libraries.

You’ll oversee the full development lifecycle, from design through to release, maintenance and product evolution, mentoring more junior engineers and reviewing contributions, raising the technical bar across the team. You’ll also guide and manage external contributors and open-source collaboration and act as a key interface with the developer community, incorporating feedback into product direction.

Location / WFH:

You can work from most of the time, collaborating via Slack and meeting up with the team at the dog friendly office in North London for tech talks, lunch and learn events etc. around once a month.

About you:

• You're a senior software engineer with experience of building developer tooling and APIs
• You have strong hands-on experience with Ruby, TypeScript and React
• You have experience within a product focussed B2B SaaS environment
• You have experience of making technical decisions that drive projects and raise the bar
• You're comfortable with AI tools such as Claude and Cursor and understand how they can be used to optimise processes
• You're customer and product focussed
• You're collaborative and pragmatic with experience of technically leading and mentoring others
• You have a thorough understanding of Computer Science fundamentals such as OOP, Data Structures, Design Patterns

What's in it for you:

As a Full Stack Engineer / Technical Lead you will earn a competitive salary package including:

• Salary to £130k
• 28 days annual leave
• Enhanced maternity and parental leave packages
• Your choice of kit and home-station set up
• 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
• Fully paid one month sabbatical at five years' service
• Gym subsidies, Cycle to work scheme and more

Full-time