Senior Software Engineer (JVM, Kotlin)

Simple Machines; Greater London; Hybrid; GBP 60,000 - 80,000; Full time

Job summary

A leading technology firm is seeking a Senior Software Engineer to design and build essential backend services for a scalable marketing platform. The role requires a strong foundation in JVM-based development, preferably Kotlin, along with robust SQL experience and knowledge of automated testing. You will collaborate within a dynamic hybrid team, delivering solutions for a global telecommunications client and facing meaningful engineering challenges. Ideal candidates will have experience in cloud infrastructure and data-driven API design.

Qualifications

• Strong foundation in JVM-based development, with a preference for Kotlin.
• Experience designing and implementing data-driven APIs.
• Solid SQL experience, including schema design and performance-aware queries.
• Deep experience with automated testing ensuring robust quality assurance.

Responsibilities

• Design and build backend services for a scalable marketing platform.
• Own the design of APIs and supporting infrastructure.
• Document technical designs and requirements for internal teams and clients.
• Deliver end-to-end solutions, from build to support.
• Collaborate in a hybrid setup with remote and in-person teams.

Skills

JVM-based development

Data-driven APIs

Large-scale web services

SQL schema design

Automated testing

React

TypeScript

AWS

Docker

Tools

Terraform

Kubernetes

Job description

Overview

Simple Machines is a leading independent boutique technology firm with a global footprint across London, Sydney, San Francisco, and New Zealand. We operate at the intersection of data, AI, machine learning, data engineering, and software engineering—building bespoke platforms and products that turn complex data into real-world outcomes.

We work with enterprises, technology companies, and governments to help them better understand their organisations, customers, and citizens. Our teams design and build large-scale data platforms, intelligent systems, and high-impact software products.

Role

Senior Software Engineer (JVM, Kotlin)

About Simple Machines

Hybrid · Full-time · London, UK

We engineer data to life™.

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

The Team

You'll join a high-performing engineering team working on a large-scale machine learning platform for a global telecommunications client. The team operates with a high degree of autonomy and shared ownership. Engineers work across the full stack, support one another's growth, and collaborate closely with data scientists and adjacent teams to design cross-system solutions.

Strong engineering culture, real influence, and meaningful problems to solve.

What We're Looking For

Core Experience

• 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)

Frontend & Full Stack Exposure

• Experience with React, TypeScript, Redux, and Tailwind (or similar modern frameworks)

Cloud & Infrastructure

• Experience with AWS, GCP, Azure, or similar
• Infrastructure-as-code (Terraform, CloudFormation, etc.)
• Containerised deployments using Docker, ECS, Kubernetes, or equivalent

Nice to Have

• Exposure to Scala or functional programming concepts
• Experience with asynchronous and highly concurrent backend frameworks (e.g. Ktor, http4k, Play, RxJava)
• NoSQL experience (DynamoDB, Cassandra, BigTable, Cosmos DB, etc.)
• Strong Git workflow experience and the ability to adapt workflows to project needs
• A genuine appetite for learning and adopting new technologies quickly