cover image
Harrington Starr

Senior Software Engineer

Hybrid

London, United kingdom

£ 1,100 /day

Senior

Freelance

05-03-2026

Share this job:

Skills

Python Java C# Data Engineering Test Architecture angular react AWS Analytics .NET Kafka PostGres

Job Specifications

Senior Front Office Software Engineer – Real‑Time Trading Systems

Contract – Inside IR35

£700 - £1100 per day

London – Hybrid (3 days in office)

The Short Version.

You must be a senior software engineer with experience in trading environments.

You need to be a well-rounded engineer in Python, C# / .NET or other object-oriented languages. With an ability to deliver real-time cloud based solutions at the speed a trading desk needs.

Want to know more? Click to apply or read the full JD below.

Full Job Description:

You’ll be joining a global energy trading environment, building real‑time systems and Front Office tooling that directly support gas and power traders. This is a hands‑on engineering role in a fast‑moving setting where delivery cycles are measured in hours and days, not weeks.

Working across UK and Denmark engineering teams, you’ll take ownership of critical trading systems, help shape architectural direction, and deliver high‑impact software that underpins pre‑trade decision‑making.

What You’ll Do

Build, enhance and support real‑time trading systems across gas and power markets
Own delivery end‑to‑end: design, build, test, deploy and iterate
Partner closely with traders, analysts and quants to refine rapidly evolving requirements
Contribute to strategic rebuild efforts, including a long‑term shift towards C#
Improve ingestion, validation and analytics tooling across Front Office platforms
Shape architecture and steer the technical direction of key systems
Collaborate with a mixed London/Denmark engineering team in a highly business‑facing environment

Tech Stack

Languages:

C# / .NET (strategic direction)
Python (current tooling base)
Java or other OO languages also considered

Cloud:

AWS (current environment)

Frontend:

Angular
Svelte
React experience also relevant

Data / Messaging:

Strong database fundamentals (Postgres, ClickHouse or equivalent)
Kafka or similar real‑time messaging technologies

What We’re Looking For

Strong software engineering experience in Front Office or real‑time trading environments
Proven ability to build and support low‑latency or event‑driven systems
Comfortable working directly with demanding trading stakeholders
Broad engineering skillset — backend first, with UI capability where needed
Ability to operate in a hybrid Python/C# world and contribute to long‑term technical evolution
Architectural awareness and ability to shape platform design
Gas/Power trading experience preferred — otherwise must speak confidently about the markets they've supported

This is not a data engineering role — it’s a business‑focused, full‑stack/trading systems engineering position suited to someone who thrives in real‑time, high‑ownership environments.

Team & Culture

London team of 8 engineers (mix of backend, infra and support)
European team of 5 engineers working closely with London
Highly collaborative, business‑facing, delivery‑focused engineering culture
Fast iterations, high visibility, and systems used directly on the trading floor

Apply Now

Click the link provided

OR

Email: Barry.Ansell@Harringtonstarr.com

About the Company

Harrington Starr is a multi-award winning financial technology recruitment business based in London, Belfast and New York City. Founded in 2010, we are specialists in technology, change & transformation and sales recruitment and have helped clients and candidates across 5 continents. Our diverse range of clients include banks, hedge funds, vendors, service providers, payment providers, asset managers, start-ups, disruptors and many more. The one thing they have in common though is that they trust Harrington Starr with their... Know more