Senior Backend Engineer, Happl

Location

London
2 days a week in office (Waterloo, London)

Remote Work

WFH Opportunities mentioned under company benefits

Employment Type

Not explicitly stated

Experience Level

Mid and Senior level
4+ years experience as a Backend or Software Engineer

Salary Information

Salary not provided explicitly in the job posting
Salary benchmarks for Backend Engineer (Senior/Mid) range approximately from 50k to 120k (visual scale shown)
Additional compensation: Commission + Equity

Company Mission

Were building the next generation of employee benefits infrastructure. We help global teams design, manage, and scale benefits that actually work for their people by using AI, across flex allowances, benefits, insurance, recognition, and wellbeing, all in one intelligent platform. We partner with fast-growing and enterprise organisations to replace fragmented benefits stacks with a single, flexible system that works globally, adapts locally, and puts employees first.

Role

Who you are

4+ years experience as a Backend or Software Engineer
Strong experience with modern backend languages and frameworks (e.g. Typescript, Golang)
Experience designing and consuming APIs (REST, event-driven systems)
Solid understanding of databases (SQL / PostgreSQL) and data modelling
Experience building and scaling production systems
Familiarity with cloud infrastructure and CI/CD workflows
Comfortable working with integrations and third-party services
Experience using AI tools (e.g. ChatGPT, Claude) as part of your workflow
Clear communicator who works well with both technical and non-technical stakeholders
Proactive, detail-oriented, and comfortable taking ownership
If you dont meet every requirement but feel this role fits your trajectory, wed still love to hear from you

What the job involves

Build the systems that power a global, AI-first benefits platform
Design, build, and scale backend services that are reliable, secure, and performant
Support complex real-world use cases across payroll, finance, and employee benefits
Ownership of foundational systems impacting how companies support their people
Collaborate closely with Product, Frontend, Data, and Customer teams across full development lifecycle

Focus areas include:

Backend architecture
Creation and automation of Go Rules
Data models for global benefits, allowances, and payments
Platform reliability, performance, and security
Integrations with third-party systems (HRIS, payroll, finance)
AI-enabled workflows and automation

Responsibilities:

Designing, building, and maintaining backend services
Owning core business logic across benefits, allowances, payments, and reporting
Working with product and frontend teams to define and deliver features end to end
Building scalable data models and ensuring data integrity across systems
Integrating with external platforms (HR, payroll, finance, payments)
Improving system performance, reliability, and observability
Writing clean, well-tested production-ready code
Using AI tools to accelerate development, debugging, and iteration
Contributing to technical decisions, architecture,best practices
Supporting a strong engineering culture focused on qualityand ownership

Skills Mentioned Explicitly or Implicitly:

SQL / PostgreSQL (databases)
TypeScript (backend language)
Golang (backend language)
REST API design/consumption
Event-driven systems design/consumption
Cloud infrastructure familiarity
CI/CD workflows knowledge
Integration with third-party services/systems(HRIS/payroll/finance)
AI tools usage in workflow(ChatGPT/Claude)

Company Benefits:

Personal Wellbeing Flex Card
Learning & Development Flex Card
Share Options
Choose your own techand setup
28 days holiday(including bank holidays)

Additional Notes:

Happl is an AI-powered global employee benefits platform focused on building flexible employee benefit infrastructures globally.The company has 120 employeesin B2B HR SaaS sector.Total funding $17.3m including Series A($11m May2026)and Early VC($3m Mar2024).