Backend Engineer (C++) – Metal 3D printing

Nexus is an early-stage startup, founded in 2024 and spun out of Imperial College London, building the data, software, and intelligence layers of metal 3D printing. Our platform, NEXUS, ingests terabytes of high-dimensional, multi-modal sensor data and uses physics-informed machine learning to infer the internal quality of parts as they're built. We work with leading aerospace, defence, and medical manufacturers, and we're backed by top deep-tech investors. We're on a mission to accelerate manufacturing of high-value safety-critical parts with additive manufacturing.

The Opportunity

As our Backend Engineer, you'll own the high-performance core of our platform: the C++ systems that ingest, process, and store high-rate, multi-modal sensor data from metal 3D printing machines, serve machine learning inference in production, and display 3D insights to the end user. Our software runs where our customers build parts, on-premise, inside industrial factories, so performance and reliability are critical. Your work will directly enable aerospace, medical, and automotive manufacturers to produce mission‑critical components with high confidence.

Core Responsibilities

• Design and develop our core C++ libraries for high-throughput sensor data ingestion, processing, and storage
• Build and maintain Python bindings and APIs that expose backend functionality to our ML and application teams
• Integrate ML model inference into the production pipeline and optimise it for resource‑constrained, on‑premise environments
• Performance focused design: profiling, concurrency, memory management, and I/O optimisation for very large datasets (multi‑gigabyte builds, billions of points)
• Interoperate with 3D geometries, including meshes, point clouds, and spatial queries.
• Realtime data streaming through WebSockets.
• Maintain robust cross‑platform builds, packaging, and deployment for customer environments (Windows and Linux)
• Implement robust error handling, logging, and monitoring for production systems running unattended at customer sites

Required Expertise

• Bachelor's degree or equivalent experience in computer science, engineering, or related field
• 3+ years of hands‑on experience writing production C++ (C++17 or later)
• Strong grasp of systems fundamentals: concurrency and multithreading, memory management, and performance profiling
• Experience with cross‑platform build systems and dependency management (e.g. CMake, vcpkg/Conan)
• Working proficiency in Python and experience with C++/Python interoperability
• Experience designing software that handles large datasets or high‑rate data streams
• Solid understanding of WebSockets and real‑time data streaming between backend services and clients
• Experience with 3D data processing: meshes, computational geometry, and spatial algorithms (e.g. ray casting, spatial indexing)
• Exceptional problem‑solving abilities with a bias toward practical solutions
• Eligible to work in the UK

Preferred Qualifications

• Experience deploying and operating systems across a range of infrastructure: public cloud (e.g. AWS), private/internal cloud, and on‑premise or restricted‑network industrial environments, including networking and storage (e.g. NAS)
• Low‑level Windows knowledge: services, networking, storage, and system‑level debugging
• Experience with pybind11 or similar binding frameworks
• Experience deploying ML inference in C++ (e.g. ONNX Runtime, TensorRT, libtorch) and GPU programming (CUDA)
• Knowledge of scientific data formats, particularly HDF5
• Experience with very large point clouds or volumetric data
• Background in signal processing, computer vision, or sensor systems
• Experience with scientific or industrial software development
• Startup experience or demonstrated ability to thrive in ambiguous, fast‑paced environments

Why Join Nexus

• Impact: Your work will directly enable more sustainable, efficient manufacturing of critical components
• Ownership: Your work shapes the core software architecture
• Team: Join a diverse, multi‑disciplinary team of experts passionate about solving meaningful problems

Benefits

• Comprehensive healthcare package
• Central London location with excellent facilities (in‑person role)
• Regular team events and learning opportunities