Backend Engineer

xAI

SpaceXAI’s mission is to create AI systems that can accurately understand the universe and aid humanity in its pursuit of knowledge. Our team is small, highly motivated, and focused on engineering excellence. This organization is for individuals who appreciate challenging themselves and thrive on curiosity. We operate with a flat organizational structure. All employees are expected to be hands-on and to contribute directly to the company’s mission. Leadership is given to those who show initiative and consistently deliver excellence. Work ethic and strong prioritization skills are important. All employees are expected to have strong communication skills. They should be able to concisely and accurately share knowledge with their teammates. ABOUT THE ROLE: As an ideal candidate you have a good understanding of how highly scalable and reliable production infrastructure is built. Most of our backend infrastructure is written in Rust. So familiarity with a compiled language such as C++, Rust, or Go is highly beneficial. RESPONSIBILITIES: * Build the SpaceXAI API that serves our models to developers worldwide * Own the end-to-end system responsible for high-throughput inference, handling billions of tokens per minute with low latency and high availability, including model serving infrastructure, request routing, SDK development, rate limiting, observability, and efficient scaling BASIC QUALIFICATIONS: * Expert knowledge of either Rust or C++ * Experience in designing, implementing, and maintaining reliable and horizontally scalable distributed systems * Knowledge of service observability and reliability best practices * Experience in operating commonly used databases such as PostgreSQL, Clickhouse, and MongoDB PREFERRED SKILLS AND EXPERIENCE: * Experience with LLM inference engines and serving frameworks (e.g., SGLang, TensorRT, vLLM) * Experience designing or building with agent SDKs and agent orchestration frameworks * Experience with Docker, Kubernetes, and containerized applications * Expert knowledge of gRPC (unary, response streaming, bi-directional streaming, REST mapping) COMPENSATION AND BENEFITS: £107,000 - £262,000 GBP Base salary is just one part of our total rewards package at SpaceXAI, which also includes equity, comprehensive healthcare and dental coverage, cash plan, income protection, life insurance, and various other discounts and perks. SpaceXAI is an equal opportunity employer. For details on data processing, view our Recruitment Privacy Notice.

CarbonChain

ABOUT CARBONCHAIN Want to work on the most pressing challenge of our generation? If you have experience building exceptional products, know how to execute at scale, and want to help build a company for the long term, we'd love to hear from you. CarbonChain helps the world’s biggest supply chains measure and reduce their carbon emissions, using verified primary data where possible, and robust defaults where it isn’t. We build software that turns messy, real-world operational and supplier information into decision-grade carbon and compliance insights, so teams can act: improve sourcing, meet regulations like CBAM, and deliver credible reporting to customers, investors, and regulators. We’re a product-led company operating in a high-stakes domain. Data quality, auditability, reliability, and trust matter as much as speed. If you enjoy building systems that customers rely on, and shipping improvements that measurably change behaviour across a network, you’ll feel at home here. OUR PRODUCT Our platform combines real-world emissions data with our customers' supply chain information to create actionable insights. We help sustainability teams answer critical questions: Where are the emissions hotspots in our supply chain? Which suppliers should we prioritize? What's the carbon impact of switching vendors or routes? A major focus of what we’re building right now is supplier engagement and CBAM data management: * enabling installations (goods producers) to prepare, manage, and share CBAM datasets through guided product carbon accounting workflows; * improving our supplier database and connection management to support sharing across supply chains; * and building ingestion pipelines that turn messy customer files into structured, provenance-tracked, insights-ready data. Beyond CBAM, our platform supports product and corporate carbon footprinting used by some of the world’s largest commodities producers and traders, helping teams move from data collection to credible reporting and decision-making ABOUT THE ROLE We're looking for a Senior Backend Engineer to build robust, scalable systems that power our product. This is a high-impact individual contributor role where you'll own meaningful projects and directly influence how our engineering team works. You'll focus on shipping well-crafted backend systems while collaborating closely with the team to deliver features that solve real customer problems. We value engineers who take initiative, care about the details, and aren't afraid to venture beyond their primary domain when needed. WHAT YOU'LL DO * Design and build backend systems that handle complex carbon data workflows and integrations * Own features from technical design through deployment - you'll drive your projects forward with autonomy * Write clean, maintainable code and establish patterns that other engineers can follow * Collaborate with Product Managers and designers to translate product requirements into technical solutions * Contribute to architectural decisions and help shape our technical standards * Occasionally jump into frontend work when needed - we value versatility and believe the best solutions come from understanding the full picture * Participate in code reviews and help maintain high engineering standards across the team WHAT WE'RE LOOKING FOR * 5+ years building complex software systems across the full development lifecycle * Strong backend engineering skills with experience building modern web applications * Deep knowledge of Python and familiarity with frontend technologies like TypeScript * Hands-on experience with relational databases, job queues, and asynchronous processing * Knowledge of IaC/Terraform and modern CI/CD practices * Strong collaboration skills—you work closely with Product to ideate features, advise on trade-offs, and iterate on what we've built * A product-minded approach: you understand why you're building something, not just how * Bonus: startup or SaaS experience * Bonus: experience with data-intensive systems or climate/sustainability tech   WHAT WE OFFER Meaningful impact and accelerated growth This is a rare opportunity to work on technology that directly addresses the climate crisis while shaping the future of a fast-growing company. You'll have significant influence over our technical direction and product strategy - the kind of impact that typically takes decades to achieve elsewhere. You'll tackle diverse challenges, work across the full stack of problems (technical and otherwise), and own meaningful projects from start to finish. If you want to learn quickly, take on real responsibility, and see the direct results of your work, this is the place to do it. Competitive salary and benefits: * 28 days annual leave * £500 home office setup allowance * £2,000 annual learning allowance * Private healthcare * Generous parental leave policy * Weekly team lunches in the office * Office gym, and cycle to work scheme CarbonChain values diversity and inclusion and welcomes applications from candidates with diverse backgrounds.  If you think your skills and experience match what we’re looking for and you’d like to join the next Climate Tech industry unicorn, please get in touch! You can find out more about interviewing at CarbonChain at https://www.carbonchain.com/careers/interview-process.

heycar

Since August 2019, we’ve been making it easier for customers to find the right vehicle, and for automotive retailers to sell them.  More recently, we’ve been on a journey… In June 2025 we were acquired by Volkswagen Financial Services UK (VWFS UK) and our mission is simple: build the right tech solutions for Volkswagen Group UK and its retailers, so they can deliver the best possible experiences to their customers.  We’re a mix of problem-solvers, innovators, and team players who care about doing great work and making a difference. We thrive on collaboration, innovation, and a shared commitment to excellence. We deliver impactful solutions at pace that put the customer at the centre.  If you're looking for a meaningful challenge, and want to help shape the future of automotive experiences, then read on…   About the role :  Join the team and play a pivotal role in designing and building highly scalable and maintainable backend services. You'll have the opportunity to leverage and suggest the latest tools and techniques, collaborating closely with Product, Design, and Sales teams. We encourage sharing technical solutions and product ideas through code and design reviews, pair programming, and presentations, all while continuously improving our Agile processes.   What you’ll do: Our culture empowers our talented developers to develop using whichever tools we need to get the job done. To face the many challenges, including brilliant customer experience, data processing, microservice architecture and more. * Hands on building highly scalable and maintainable backend services * Turn intricate business needs into robust technical designs and high-level architecture * Use appropriate tools for development and being proactive in suggesting new tools, frameworks or techniques * Collaborate across functional teams including Product, Design and Sales * Share technical solutions and product ideas through code and design reviews, pair programming, and presentations * Highlight areas we can improve on as a team practising Agile processes * Offer expert technical leadership and support while mentoring our developing engineering talent   Our Tech Stack: We use the tools we need to get the job done. We primarily use the following tools and frameworks (some have been added in the past year, and more are planned): Python Django FastAPI AWS ElasticSearch Postgresql Kafka Github Kubernetes Redis   What you’ll need: * Strong technical skills to design and build scalable backend services, primarily in Python (in any framework) * Analytical skills: a love for problem solving, and improving our working processes.  We are always learning * A good understanding of databases, OO design, data structures, distributed systems and SOLID principles * Strong desire to work collaboratively with both your peers and business teams * The ability to communicate technical concepts to other members of the team.   What we’ll give you: * Compensation: We offer a competitive salary + performance based bonus * Holidays: We want you to relax, you’ll have 28 days off (plus bank holidays) throughout the year. We also give you an extra day off to enjoy your birthday! * Benefits + Perks: With private medical insurance, learning and development opportunities and mental health support we’ll give you the extra boost. * Hybrid Working: We have a flexible working culture here at heycar. With hybrid working in our offices in Holborn (London) and working from home days. * Feedback: You'll be joining more than just another scale up - our team are at the heart of everything we do; here we don’t leave things unsaid, we encourage honest feedback. * A Challenge: Fast paced but not fraught. So we need you to keep up, push back and question where you see fit. * Fun: We provide a fully stocked kitchen and bar, an awesome office environment and epic socials.   If you’re ready to work with a creative, high-performing group of people we want to hear from you. Please apply directly to this role. Contact : Reece Jagger for more details.