Location
London, UK (Hybrid)

Hours
Full-time

Salary
Competitive salary package

About the Role
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. We engineer data to life™.

As a Principal 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.

Experience
Proven experience delivering complex, scalable software systems across the full stack including backend services, APIs, frontend components, data pipelines, and cloud infrastructure. Experience working in Agile environments and collaborating with cross-functional teams including data scientists and client stakeholders.

About you
Hands-on engineer who enjoys solving challenging problems and owning outcomes end-to-end. Strong communicator able to influence technical direction and work consultatively with clients and internal teams. Comfortable working in a hybrid environment with both remote and in-person collaboration. Passionate about building high-quality, maintainable software and fostering a strong engineering culture.

Qualifications
Relevant degree or equivalent experience in software engineering, computer science, or related fields is preferred. Demonstrated expertise in software design, architecture, and delivery. Familiarity with machine learning platforms and large-scale data systems is advantageous.