Senior Software Engineer in London

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 with an ability to deliver real‑time cloud based solutions at the speed a trading desk needs.

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

• C# / .NET (strategic direction)
• Python (current tooling base)
• Java or other object‑oriented 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 — otherwise must speak confidently about the markets they’ve supported

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

Contact: Barry.Ansell@Harringtonstarr.com

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