Principal Software Engineer – Hybrid, Data & ML Platform

Simple Machines; Greater London; Hybrid; GBP 120,000 - 160,000; Full time

Job summary

Simple Machines is seeking a Principal Software Engineer to lead the design and delivery of scalable, data-driven platforms. This hands-on role spans backend services, APIs, frontend components, data pipelines, and cloud infrastructure.

You'll work with client stakeholders and internal teams to set technical direction, own outcomes end-to-end, and drive high-impact software engineering across a hybrid London-based team.

Qualifications

• Strong foundation in JVM-based development (Kotlin preferred, Java welcome).
• Experience designing and implementing data-driven APIs.
• Background working on large-scale web services.
• Solid SQL experience, including schema design and performance-aware queries.
• Deep experience with automated testing (unit, integration; TDD/BDD preferred).
• Experience with React, TypeScript, Redux, and Tailwind (or similar).
• Experience with AWS, GCP, Azure, or similar cloud platforms.
• Infrastructure-as-code (Terraform, CloudFormation).
• Containerised deployments using Docker, ECS, Kubernetes, or equivalent.

Responsibilities

• Design and build backend services for a highly scalable marketing platform.
• Own the design of APIs, applications, and supporting infrastructure.
• Document technical designs and requirements clearly for both internal teams and clients.
• Deliver solutions end-to-end: build, automate, deploy, operate, and support.
• Partner with clients and delivery teams to translate business requirements into robust technical solutions.
• Work within an Agile, iterative delivery model.
• Collaborate in a hybrid setup with both remote and in-person team members and stakeholders.

Skills

Kotlin/Java JVM

API design

Large-scale web services

SQL proficiency

Automated testing (TDD/BDD)

React/TypeScript (Frontend)

Education

Bachelor's degree in Computer Science or related field

Tools

Docker

Kubernetes

Terraform/CloudFormation

Git workflow

Job description

Simple Machines is seeking a Principal Software Engineer to lead the design and delivery of scalable, data-driven platforms. This hands-on role spans backend services, APIs, frontend components, data pipelines, and cloud infrastructure.

You'll work with client stakeholders and internal teams to set technical direction, own outcomes end-to-end, and drive high-impact software engineering across a hybrid London-based team.