Senior Software Engineer in City of London

Senior Software Engineer – Node.js / Backend Development – London (Hybrid, 3 days onsite)

Are you the kind of Senior Software Engineer who enjoys taking something fast‑and‑scrappy and turning it into something scalable, elegant, and genuinely robust?

This is a chance for a Senior Software Engineer to join a small, but ambitious tech‑for‑good / IoT start‑up based in the London City Centre that’s building products to make sense of massive data streams. You’ll be part of a tight‑knit team (around ten people total, five software engineers), working on a genuinely greenfield platform with a modern stack and zero legacy.

The focus now is on maturing the codebase – re‑architecting, refactoring, testing, and scaling. As a Senior Software Engineer, you’ll play a key role in helping the team evolve from early‑stage speed to long‑term stability, with the freedom to influence both product direction and engineering quality.

What you’ll be doing:

• Building and scaling a Node.js application that sits at the core of the product.
• Designing and implementing new features for different sectors and use cases.
• Helping drive improvements in code quality, architecture, and testing practices.
• Working closely with product and engineering to prioritise, shape, and deliver features.
• Introducing best practices and guiding a shift towards cleaner, more maintainable code.

What we’re looking for:

• Strong hands‑on experience with Node.js – backend software development.
• Comfortable working across or picking up other tech as needed – e.g. AWS, React (experience with AWS & React is a bonus).
• Enthusiasm for writing clean, tested, production‑ready code.
• Experience (or interest) in data‑heavy systems, IoT, or connected devices.
• Ultimately, this is a backend focussed position, so as a Senior Software Engineer you’ll have to be comfortable with the backend nature of the role.

Seniority level

Mid‑Senior level

Employment type

Full‑time

Job function

Information Technology

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