Senior Software Engineer (JVM, Kotlin) in London

Senior Software Engineer (JVM, Kotlin) in London

London Full-Time 80000 - 98000 £ / year (est.) No working from home possible
Internetwork Expert

At a Glance

  • Tasks: Design and build scalable backend services for a cutting-edge marketing platform.
  • Company: Join Simple Machines, a leading tech firm with a global presence.
  • Benefits: Enjoy competitive salary, health benefits, and flexible hybrid work options.
  • Other info: Collaborate with a high-performing team on innovative machine learning projects.
  • Why this job: Make a real impact by solving complex problems in a dynamic environment.
  • Qualifications: Strong JVM development skills, especially in Kotlin, and experience with data-driven APIs.

The predicted salary is between 80000 - 98000 £ per year.

Simple Machines is a leading independent boutique technology firm with a global footprint across London, Poland, Sydney 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.

As a Senior Software Engineer, you’ll play a key role in delivering complex, scalable systems for ambitious clients. This is a hands-on engineering role where you’ll work across the full stack—backend services, APIs, frontend components, data pipelines, and cloud infrastructure.

You’ll collaborate closely with our internal engineering teams and client stakeholders, influencing technical direction while remaining deeply involved in design and delivery. This role suits someone who enjoys solving hard problems, owning outcomes end-to-end, and operating in a consultative engineering environment.

What You’ll Be Doing

  • 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, 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

Senior Software Engineer (JVM, Kotlin) in London employer: Internetwork Expert

Eminent Valet is an exceptional employer that prioritises employee growth and development within a dynamic and supportive work environment. As a leading valet service provider in Canada, we offer competitive pay, performance-based tips, and a clear path for advancement, all while fostering a culture of integrity and excellence in customer service. Join us to be part of a respected team that values your contributions and provides the tools you need to succeed.

Internetwork Expert

Contact Details:

Internetwork Expert Recruitment Team

We think you need these skills to ace Senior Software Engineer (JVM, Kotlin) in London

JVM-based development
Kotlin
API design and implementation
SQL
Automated testing
Unit testing
Integration testing