Senior Software Engineer (C#/Java) – Remote + 25 PTO

Threecolts LLC; Greater London; Hybrid; GBP 105,000 - 115,000; Full time

Benefits offered by this job

Salary: £110k+ per year

PTO 25 days

Healthcare & Pension

Offsites

Bonus opportunities

Remote/Hybrid

Job summary

Threecolts is seeking a Senior Software Engineer to own backend services and APIs, primarily across C# and Java‑based systems. You’ll design scalable components, debug production issues, and work with Product, QA, and DevOps to deliver reliable features for Inventory Lab.

You’ll collaborate across a product‑led ecommerce environment, writing clean code, modelling data in SQL databases, and leveraging AWS cloud infrastructure. A strong ownership mindset and excellent communication are essential.

Qualifications

• 5–8+ years of professional software engineering experience.
• Strong proficiency in C# and Java.
• Experience building and maintaining backend services, APIs, and scalable components.
• Solid understanding of REST APIs, system design, and scalable patterns.
• Experience with SQL databases and data modelling.
• Familiarity with cloud infrastructure, ideally AWS.
• Experience debugging production systems and solving issues independently.
• Comfortable working with Git and code reviews.

Responsibilities

• Own features across Inventory Lab’s C# and Java-based systems from design to production.
• Design and build clean, scalable services, APIs, and components.
• Work independently within a defined scope and balance speed with quality.
• Improve systems, debug production issues, identify root causes, and implement fixes.
• Contribute to architecture discussions and code reviews; collaborate with Product, QA, and DevOps.

Skills

5–8+ years experience

C#

Java

Backend services

REST APIs

SQL databases

AWS

Debugging

Git

Tools

SQL

AWS

Git

Job description

Threecolts is seeking a Senior Software Engineer to own backend services and APIs, primarily across C# and Java‑based systems. You’ll design scalable components, debug production issues, and work with Product, QA, and DevOps to deliver reliable features for Inventory Lab.

You’ll collaborate across a product‑led ecommerce environment, writing clean code, modelling data in SQL databases, and leveraging AWS cloud infrastructure. A strong ownership mindset and excellent communication are essential.