Senior Backend Engineer - FinTech

Open Select; Greater London; Hybrid; GBP 110,000 - 130,000; Full time

Job summary

A growing fintech scaleup in London is looking for a Senior Backend Engineer to help shape their product and engineering culture. This role involves designing and optimizing backend services using Kotlin, collaborating with cross-functional teams, and architecting robust APIs. The ideal candidate will have over 3 years of experience in building product-focused applications and a passion for working in a hybrid environment. Join a team experiencing explosive growth and make an immediate impact in a dynamic industry.

Benefits

Competitive salary

Flexible and inclusive culture

Fast career progression

Qualifications

• 3+ years of backend or full-stack engineering experience building product-focused applications.
• Strong proficiency in Kotlin or equivalent JVM languages.
• Proven experience designing scalable, reliable backend systems in SaaS or fintech settings.

Responsibilities

• Design, build, and optimise scalable backend services using Kotlin.
• Collaborate with teams to deliver user-friendly financial tooling.
• Architect robust APIs and data models.

Skills

Kotlin

Backend engineering

Full-stack engineering

Designing scalable backend systems

Collaborating in hybrid environments

Job description

Senior Backend Engineer

Location: London (Hybrid) Salary: Up to £130k + competitive equity Industry: Fintech, SaaS, B2B

What You’ll Drive

Join a fast-growing fintech scaleup revolutionising billing, CPQ, and revenue recognition for the world’s leading SaaS, AI, and fintech companies. Backed by a16z, Salesforce Ventures, and top global fintech investors, over $21M has been raised to date, fueling new product development, team growth, and international expansion.

With hundreds of clients and over $500M in revenue processed, you’ll build mission-critical financial tools, architect core backend systems, and help shape both product and engineering culture at a pivotal moment of growth.

What You’ll Focus On

• Design, build, and optimise scalable backend services using Kotlin for complex billing and revenue automation workflows
• Collaborate with product, data, and design teams to deliver seamless, user-friendly financial tooling
• Architect robust APIs and data models with best practices for high performance and reliability
• Drive backend technical direction and mentor engineering peers
• Contribute to building a strong engineering culture and operational excellence in a high-growth startup environment

Who You Are

• 3+ years of backend or full-stack engineering experience building product-focused applications
• Strong proficiency in Kotlin or equivalent JVM languages
• Proven experience designing scalable, reliable backend systems in SaaS or fintech settings
• Comfortable working in a hybrid environment with regular presence in London
• Autonomous, collaborative, and passionate about solving complex infrastructure challenges
• Experienced in fast-paced, user-centric startup or scaleup environments

Tech Stack

Kotlin

Why You’ll Thrive Here

• Explosive growth: 600%+ YoY revenue increase, multimillion-dollar funding, and global customer reach
• High ownership: Shape product and engineering strategy with immediate impact
• Experienced team: Engineers and leaders from top-tier fintech and SaaS companies
• Product and user focus: Build automation and financial tools that transform how leading companies operate
• Flexible and inclusive culture: Results-driven, hybrid work, direct leadership access
• Fast career progression: Opportunities for technical leadership and broad ownership
• Security and compliance: Work in SOC 2 and ISO 27001 certified environments, gaining deep domain expertise

This role is open to UK citizens only.