Senior Fullstack Engineer – SaaS, Hybrid London

Owen Thomas B Corp; Greater London; Hybrid; GBP 110,000 - 150,000; Full time

Benefits offered by this job

PTO program

Health benefits

Remote work

Job summary

Firstup is seeking a Senior Full Stack Engineer to design and deliver large-scale, multi-tenant cloud services with a relentless focus on availability and elegant architecture. You will own features end-to-end across the frontend, backend, and data layers while mentoring peers and elevating engineering quality.

You’ll champion shift-left testing, integrate AI-assisted tooling, and collaborate closely with Product and Design to translate requirements into intuitive user interfaces.

Qualifications

• Bachelor’s degree in Computer Science or related field, or equivalent experience.
• 8+ years building reliable, performant applications and microservices in production environments.
• Full-stack fluency across frontend, backend, and database layers.
• Proven full-stack experience across frontend (React.js), backend, and database layers.
• Contribute to production health, including on-call rotations and incident response, in a “you build it, you run it” environment.
• Technical depth in at least one engineering domain: distributed systems, multi-tenant SaaS, application databases, networking, security, serverless, event streaming, or similar.
• A genuine drive to build beautiful, intuitive products with the customer always in focus, and strong communication across teams.

Responsibilities

• Core Engineering & Ownership: Build and own scalable SaaS applications end-to-end – frontend, backend, and data layers.
• System Architecture: Design future-ready architectures and proactively close gaps before they become problems.
• Performance & Reliability: Drive system availability and performance across the stack.
• Shift Left Testing & Quality: Champion a rigorous shift-left quality culture with unit, integration, and contract testing.
• AI Integration: Leverage AI-assisted tools to accelerate development while ensuring code quality.
• Leadership: Drive best practices and mentor engineers to improve overall quality.
• Collaboration (Product & Design): Translate requirements into intuitive UI with informed technical trade-offs.
• Collaboration (Engineering Standards): Promote engineering standards across teams.

Skills

React.js

Node.js

Go

TypeScript

Ruby on Rails

Distributed systems

Education

Bachelor’s degree in Computer Science or related field

Tools

GitHub Copilot

Git

Job description

Firstup is seeking a Senior Full Stack Engineer to design and deliver large-scale, multi-tenant cloud services with a relentless focus on availability and elegant architecture. You will own features end-to-end across the frontend, backend, and data layers while mentoring peers and elevating engineering quality.

You’ll champion shift-left testing, integrate AI-assisted tooling, and collaborate closely with Product and Design to translate requirements into intuitive user interfaces.