Senior Full-Stack Engineer: Scalable SaaS & AI

Firstup; England; Remote; GBP 100,000 - 140,000; Full time

Job summary

Firstup, the world's first intelligent employee experience platform, is seeking a Senior Full Stack Engineer. You will design and deliver large-scale, multi-tenant cloud services — with a relentless focus on availability, fault-tolerance, and elegant architecture.

You'll set the bar for engineering quality and help elevate those around you. You will own frontend, backend, and data layers, collaborate with Product and Design to translate requirements into intuitive UI, and champion shift-left

Qualifications

• 8+ years building reliable, performant applications and microservices.
• Proven full stack fluency across frontend, backend, and database.
• Familiarity with Ruby on Rails, TypeScript, Go is a strong plus.
• Contribute to production health, including on-call rotations and incident response.
• Strong communication and collaboration across teams.

Responsibilities

• Build and own scalable SaaS applications end-to-end — frontend, backend, and data layers.
• Design future-ready architectures and proactively close gaps before they become problems.
• Drive system availability and performance — investigate, analyze, and resolve reliability issues across the stack.
• Champion a rigorous 'shift-left' quality culture, embedding unit, integration, and contract testing early.
• Leverage and advocate for AI-assisted tools to accelerate development while ensuring code correctness.
• Drive team-wide best practices, conduct quality code reviews, and mentor engineers.
• Partner with Product and Design to translate requirements into intuitive UI and make informed technical trade-offs.
• Champion engineering standards across teams and collaborate on solving high-impact problems.

Skills

Full stack fluency

Frontend & Backend development

System design

Education

Bachelor's degree in Computer Science or related field

Tools

Ruby on Rails

TypeScript

Go

Job description

Firstup, the world's first intelligent employee experience platform, is seeking a Senior Full Stack Engineer. You will design and deliver large-scale, multi-tenant cloud services — with a relentless focus on availability, fault-tolerance, and elegant architecture.

You'll set the bar for engineering quality and help elevate those around you. You will own frontend, backend, and data layers, collaborate with Product and Design to translate requirements into intuitive UI, and champion shift-left