Senior Backend Software Engineer - Application Development

Join Updraft: Transforming Financial Futures!At Updraft, an award-winning fintech company authorized by the FCA, we are on a mission to revolutionize how individuals perceive and manage their finances. Our innovative platform automates everyday financial decisions, making it easier for users to handle credit cards, overdrafts, and loans. Experience a comprehensive spending overview across all financial accounts with Open Banking technology. Access a complimentary credit report with personalized tips to enhance your credit score. Leverage AI-driven financial planning tailored to help users manage expenses, eliminate debts, and boost credit ratings. Utilize intelligent lending solutions designed to lower the cost of credit. With over 800,000 users and a remarkable reputation within the UK fintech landscape, Updraft has helped individuals convert approximately £500 million in high-cost credit card debt into more manageable options, paving the way for better financial health. Rated 4.8 on Trustpilot, 4.8 on the Play Store, and 4.4 on the iOS Store by our satisfied customers. Recognized as a participant in the Technation Future Fifty 2025, a prestigious program that supports innovative startups on their journey to IPO. Featured in the Sifted 100 UK startups list for two consecutive years (2024 and 2025). We are seeking talented professionals to join us in our next growth phase, offering a unique opportunity to make a measurable impact. Expect a hybrid work culture that fosters collaboration across functional teams, generous learning budgets, wellness benefits, and the freedom to innovate and directly influence our customers' financial journeys.Become part of our commitment to building a fairer credit system!

Join Mustard Systems, where we harness the power of statistical modeling to analyze sports events, enabling accurate predictions of future outcomes. By leveraging our proprietary datasets, sophisticated statistical models, and custom software solutions, we aim to deliver precise forecasts in the world of sports.We prioritize speed and real-world impact over perfection in code. If you are an engineer who excels at rapid problem-solving and thrives in a flexible, outcome-oriented environment, you'll find a home with us.Your Role:Enhance our connections to new liquidity providers using advanced web scraping and reverse engineering techniques.Create and maintain low-latency, real-time data feeds to support trading strategies based on extracted data.Improve system visibility for teams to gain insights into integration challenges and enhancements.Our agile methodology allows us to adapt plans as new information and opportunities arise. Developers play a pivotal role, taking complete ownership of their software from design through development, testing, review, and production support.Key Responsibilities:Design and Implement Impactful Features: Develop features that align with our business objectives, ensuring high-quality code that delivers measurable value.Collaborate on Code Quality: Review and test peer code to uphold functionality, maintainability, performance, and quality standards.Production Support: Take charge of your team’s software in production, ensuring stability and prompt resolution of any issues.Cross-Team Collaboration: Partner with other development teams on cross-functional projects, working alongside traders and quants to devise the best solutions to real business challenges.Participate in Out-of-Hours Support for our Software Systems.Core Technology Stack:Languages: Python (3.10+), JavaScript/TypeScript for frontend tasks, and Go for select infrastructure.Tools: RabbitMQ and Kafka for messaging, PostgreSQL and Redis for data storage.Environment: Linux servers.Observability: OpenTelemetry, Prometheus, Grafana, and Zabbix.Required Qualifications:Solid experience in software development, particularly with Python.A degree in Computer Science or a related quantitative field from a recognized university.Excellent communication skills, enabling you to explain complex technical concepts to both technical and non-technical audiences.Strong decision-making skills, with an ability to make informed trade-offs in implementation and architectural decisions, balancing innovation with practicality.Experience with web scraping and related technologies is essential.

As a Senior Backend Developer specializing in Ruby on Rails, you will play a pivotal role in architecting, developing, and validating server-side logic for web applications. Your expertise will be essential in crafting efficient, reusable, and robust Ruby code, while optimizing systems for peak performance and scalability. You will work collaboratively within cross-functional teams, integrating front-end components into our applications. Your responsibilities will also include conducting code reviews, mentoring junior developers, and converting business requirements into effective technical solutions.The ideal candidate will possess a Bachelor's or Master's degree in a related discipline, along with a minimum of eight years of hands-on experience in Ruby on Rails development. You should be well-versed in various software testing methodologies, demonstrate strong analytical skills, and have excellent proficiency in English.

Are you an experienced Laravel developer with a passion for crafting robust backend systems? If so, we would love to connect with you! Join the Trybe team as a Senior Backend Developer and play a pivotal role in our mission to deliver exceptional software solutions in the industry. About Trybe:Trybe is a forward-thinking startup dedicated to providing innovative cloud-based software to clients in the hotel, spa, and wellness sectors. Our goal is to transform both guest experiences and back-of-house operations. Founded in 2020, we are proud to partner with leading spa and leisure operators globally. We foster a high-performance, collaborative team culture, welcoming talented individuals who thrive in a dynamic startup environment as we continue to expand.Key Responsibilities:Develop and maintain the Trybe Laravel backend, which powers our entire platform.Create APIs for frontend engineers, facilitate integrations with partners, and manage data processing jobs.Write extensive tests using Pest to ensure top-quality code delivery.Collaborate closely with engineering and customer experience teams to implement innovative features that meet client needs.Contribute ideas throughout the product development cycle to enhance feature quality.Who We Are Looking For:A minimum of 5 years of commercial experience with Laravel.A strong passion for technology and problem-solving.Ability to write clean, maintainable, and thoroughly tested code.A self-motivated learner who thrives in a fast-paced environment.Excellent communication skills and a collaborative team player.Experience handling large datasets, as we process millions of bookings annually.Proficient in building efficient RESTful APIs.Bonus Skills:Familiarity with MongoDB and Eloquent.Experience using Elasticsearch for data aggregation and reporting.

Join xAI as a Backend & Infrastructure Developer Experience Engineer, where you will enhance our internal developer tools to boost productivity across the organization. Your mission will be to build and optimize applications for debugging local environments, visualizing production data, and accelerating our CI pipelines. We are looking for a passionate and skilled engineer who thrives in a collaborative and innovative environment.

At Zaizi, we are on the lookout for a highly skilled Senior Backend Software Developer who possesses exceptional technical expertise and a genuine enthusiasm for enhancing user experience and outcomes. In this role, you will take ownership of your deliverables while also collaborating with a multidisciplinary team to foster innovation and share creative ideas.Our work environment is inclusive, modern, friendly, and democratic, where we value bright, positive-thinking individuals with a proactive mindset. If you thrive on challenges and aspire to excel in your field, you will find a perfect fit with our team!

Join Version 1 as a skilled Python Developer, where you will play a pivotal role in designing and implementing robust applications and systems. Collaborate with a talented team in our Digital, Data, and Cloud departments to deliver innovative solutions that meet our clients' needs.

At Spotify, we are on a mission to revolutionize the way creators and listeners engage with long-form storytelling through our Audiobooks initiative. Our objective is to create a seamless ecosystem for audiobook content, facilitating smooth transfers from publishers to listeners. This includes building the robust systems necessary for content ingestion, processing, and efficient delivery across our rapidly expanding global catalog. We are seeking a talented Senior Backend Engineer to join a dynamic and impactful team within the Audiobooks Pipeline sector. This team's primary responsibility is to design and scale systems that handle the ingestion, processing, and transformation of audiobook and eBook content, metadata, and royalties, ensuring that listeners receive the right content with utmost efficiency and quality. While this role encompasses full-stack responsibilities, the emphasis will be on backend and data-centric development. We are looking for an individual who thrives in uncertain environments, is passionate about learning, and is excited to tackle complex challenges across the tech stack.

Join Our Team!At Plum, we are revolutionizing how people save and invest. Our mission is to empower individuals to grow their wealth for life, whether they are saving for their first home or enjoying retirement. Since our inception in 2016, over 2 million users across 10 European countries have saved more than £2 billion with our innovative automation and AI technology. We've been recognized with awards from esteemed organizations like Deloitte and Finder, reflecting our commitment to excellence.We are a passionate team of over 200 Plumsters working collaboratively across Europe, and we are eager to welcome more talented individuals to help us achieve our vision.Your RoleAs a Senior Backend Engineer at Plum, you will play a crucial role in shaping our technology and product offerings. We seek engineers who are not only technically adept but also understand the importance of delivering outstanding products to our customers.

TL;DRDeducta is a rapidly expanding startup catering to some of the globe's most prestigious enterprises. With strong funding, we are committed to addressing today's most significant business challenges.We are seeking a Senior Backend Engineer who will play a pivotal role in the design, development, and upkeep of our core systems.In this role, your key responsibilities will include:Creating and sustaining high-performance, low-latency APIs for enterprise-level data processing systems.Delivering exceptional code promptly. Location: London, UK. Our office is situated near London Bridge, and we prioritize in-person collaboration. Compensation: The total compensation for this position begins at £150,000. Visa Sponsorship: We are willing to sponsor a visa for the ideal candidate to join our team. What is Deducta?Deducta is a leading data intelligence platform for global corporations. We provide unparalleled clarity into mission-critical data for some of the world's largest and most intricate organizations, starting with spend data.We are at the forefront of significant business transformations. Our partners leverage Deducta to achieve impactful results at remarkable speeds.‍What is the Role?We process vast datasets containing essential enterprise information from diverse sources and formats, structuring it effectively. Our system utilizes cutting-edge LLMs to tackle this challenge with unmatched precision and at previously unimaginable scales.As a Senior Backend Engineer, you will be responsible for designing, developing, and maintaining the foundational architecture of our platform as it expands.Your contributions will include:Designing, constructing, and maintaining data ingestion and processing engines capable of supporting mission-critical operations for the largest firms globally.Developing and sustaining ultra-fast, high-volume, and well-documented APIs to facilitate these systems.Driving business growth through a blend of creativity and experimentation to enhance our product, alongside proactive problem-solving for our clients.Working closely with both technical and non-technical team members to comprehend our customers' challenges and create solutions that address them.Success in this role means:Leading development initiatives from concept to production.Consistently driving enhancements and new features. Who will be the right fit?We are in search of a technically outstanding engineer who excels in a role that offers autonomy and ownership.You might be a great fit if you possess…Strong experience in object-oriented programming within cloud environments (e.g. AWS, GCP, or Azure), with .NET experience considered a plus.Familiarity with SOLID principles, domain-driven design, and Clean Architecture methodologies.A passion for...

Join Nevis: Pioneering AI Wealth ManagementAt Nevis, we're on a mission to revolutionize wealth management through cutting-edge AI technology. Our innovative platform is designed to empower financial advisors, enabling them to enhance client relationships while our AI automates time-consuming workflows. As we build the future of wealth management, we have secured $40 million in funding from top-tier investors including Sequoia Capital, ICONIQ, and Ribbit, and are led by a talented team of ex-Revolut executives.Your Impact as a Software Engineer (Python)We are seeking a talented Software Engineer (Python) who is passionate about developing robust AI-driven platforms. In this key role, you will design and implement Python-based systems and services that drive intelligent workflows for leading financial firms. You will work on applied AI, data pipelines, model execution frameworks, and backend components that support our innovative AI products.If you thrive in a fast-paced environment, love creating production-grade AI solutions, and are eager to see your ideas come to life quickly, Nevis is the place for you. You'll join a world-class engineering team dedicated to building scalable AI systems.Your ResponsibilitiesDesign and enhance Nevis’ Python-based AI platform, enabling core workflows and agentic automation.Develop model orchestration, data processing pipelines, and execution runtimes for our applied AI features.Create scalable APIs and services that facilitate rapid development and deployment of AI systems.Architect systems for model inference, prompt execution, and multi-step agent reasoning.Maintain high engineering standards through clean code practices and CI/CD workflows.Collaborate with AI engineers, product managers, and designers to deliver impactful features used by thousands.Take ownership of greenfield AI platform components, from architecture to production.Engage in design and code reviews that shape Nevis’ technical future.

Senior PHP Backend Developer - £500 per day (12+ Months, Remote Work Available, Outside IR35)We are seeking an experienced PHP Developer to join our team, working on an innovative Greenfield backend REST API project tailored for the transport sector. Collaborating closely with a Senior API Engineer, you will be part of a smaller, established, and friendly agency dedicated to delivering a significant project for a prominent client in the transport industry.Work Location:Options available in London, Bristol, or Cornwall, with full flexibility for remote work.

About UsAt Heidi, we are pioneering an AI Care Partner that assists healthcare professionals at every stage, from documentation to patient care delivery. Our mission is to enhance healthcare capacity while maintaining a deeply human touch. In just 18 months, we have reclaimed over 18 million hours for clinicians and facilitated more than 73 million patient visits. Currently, Heidi powers over two million patient interactions weekly across 116 countries in more than 110 languages.Founded by healthcare professionals, Heidi unites clinicians, engineers, designers, scientists, creatives, and mathematicians, all dedicated to enhancing the human connection central to healthcare. With nearly $100 million in funding, we are expanding our reach in the USA, UK, Canada, and Europe, collaborating with major health systems, including the NHS and Beth Israel Lahey Health, among others.We are agile in our approach, focused on what works, and poised to shape the future of healthcare. Are you ready to take on this challenge?Your RoleAs a Senior Backend Engineer, you will be instrumental in executing backend features, leveraging your deep technical understanding to meet user requirements. You will thrive in a hyper-growth startup environment, with substantial experience in building SaaS products.With a solid grasp of the challenges engineers face, you will prioritize key features and capabilities through effective design principles. Your ability to bridge technical specifics with business needs will enable you to transform high-level concepts into practical solutions.Embracing challenging scenarios, you will appreciate the dynamics of a flexible, flat-structured work environment and quickly navigate the complexities of developing AI healthcare products on an international scale. We believe that exceptional talent can emerge from diverse backgrounds; if you have a proven history of delivering technically demanding products and features, we want to hear from you.

Join Spotify as a Senior Backend Engineer - Subscriptions and play a pivotal role in enhancing our subscription services.In this position, you will collaborate with cross-functional teams to design and implement scalable backend systems, ensuring seamless integration and exceptional user experiences.

Join Zaizi as a Senior Backend Software Developer, where you'll leverage your robust technical expertise while enhancing user experiences and outcomes. You will be a dependable contributor to your projects and an innovative thinker within our collaborative multidisciplinary team.At Zaizi, we foster an inclusive, modern, and friendly work culture that values fresh ideas and a proactive mindset. If you are passionate about pushing your limits and excelling in your role, you'll thrive in our environment!

Join Aircall, a revolutionary unicorn in the AI-powered customer communications sphere, trusted by over 22,000 companies globally to enhance revenue, expedite issue resolution, and empower customer-facing teams. We are transforming the landscape of customer communications by integrating voice, SMS, WhatsApp, and AI into a unified workspace.Our growth is driven by a straightforward principle: to enable teams to work smarter, not harder. Our AI Voice Agent automates routine calls, while AI Assist simplifies post-call tasks, and AI Assist Pro provides real-time insights, allowing individuals to excel in their roles. This synergy results in increased revenue, quicker resolutions, and scalable teams.Headquartered in Paris, with a solid presence in North America anchored in Seattle, Aircall also has teams in vibrant cities such as Madrid, London, Berlin, San Francisco, New York City, Sydney, and Mexico City. Our product is beloved by customers, and we are rapidly scaling, supported by top-tier investors and continuous AI advancements across multiple product lines.At Aircall, you'll become part of a dynamic company. We are ambitious, focused on product development, and execution-oriented, with a clear impact, swift decision-making, and genuine growth opportunities.Our Work Culture at Aircall: We prioritize customer satisfaction, leverage data for decision-making, and are dedicated to delivering significant outcomes. We cherish ownership, continuous improvement, and thoughtful agility. If you thrive in a collaborative, fast-paced environment where trust and impact are essential, you will thrive here.Position Overview:As a Senior Backend Software Engineer, you will take charge of designing, developing, deploying, and maintaining essential features that enhance customer value on our voice platform.You will be expected to advocate for best practices, mentor team members, and contribute to the broader Engineering community as part of your daily responsibilities.Quality, excellence, and agility are at the core of our delivery process, and you will play a pivotal role in elevating these standards.Utilizing a diverse array of backend technologies tailored to specific needs, all hosted on AWS, we create resilient services that deliver added value on top of voice while fully integrating with our customers' critical business tools (CRM, Helpdesk, E-Commerce, etc.).

About 9fin9fin is a cutting-edge AI platform revolutionizing the global debt markets, which represent the largest asset class exceeding $145 trillion.The landscape of debt markets is extensive, global, and essential, yet it often relies on disjointed data, PDFs, and manual processes. 9fin transforms this outdated infrastructure by providing a unified platform that consolidates proprietary credit data, in-depth analysis, and efficient workflows across international markets.Currently, 9fin empowers over 300 prestigious institutions worldwide, including leading banks, asset managers, private equity firms, law firms, and consulting advisors. The company is experiencing rapid growth, particularly in the US, with exceptional retention rates driven by robust workflow adoption.We are at a pivotal moment. With a validated product-market fit and strong global demand, 9fin is propelling towards becoming the definitive platform for debt markets globally.What You'll Work OnAs a Senior Backend Engineer on our Structured Credit team, you will contribute to the development of our market-leading CLO product and assist in the launch of a new vertical.Our team is dedicated to making a significant impact, leveraging technology to create value for the business. While we have overarching business goals, we enjoy the autonomy to define our team objectives and determine our success metrics. We uphold accountability and proactive behaviors such as ownership.Lead projects within a cross-functional team by defining and designing systems, building proof of concepts, and delivering new service functionalities—including APIs, data processing, and automation—while collaborating with Product and Clients.Engage in backend development and engineering primarily on the services and web applications hosted on the 9fin platform.Play a crucial role within project teams as a senior individual contributor, conducting code reviews, mentoring fellow developers, and participating in early research and experimentation with new technologies to provide insights for new features and products.Continuously enhance the 9fin codebase by seizing opportunities to automate, refactor, and document processes when it has the most significant impact.Work across diverse web platforms involving complex financial data modeling, intricate access control logic, environmental data capture, integration of ML/AI prediction services, and data visualization.

Your Mission As a Senior Backend Engineer within our Commercial Technology team, you will play a pivotal role in shaping On's digital ecosystem. You'll be responsible for designing, developing, and scaling the essential services that drive our global e-commerce platform, B2B partner portals, and retail experiences. Your contributions will significantly influence how we present product information, facilitate the checkout process, and enhance the end-to-end e-commerce user experience for our customers and partners, ensuring a seamless and premium interaction that bolsters our commercial success. Your Responsibilities Design, develop, and maintain robust and scalable backend services utilizing our modern technology stack, focusing primarily on NestJS, TypeScript, and GraphQL. Take ownership of key components within our Commercial Technology team, ensuring performance, reliability, and alignment with the needs of diverse client applications (web, mobile, and third-party integrations). Collaborate closely with frontend engineers, product managers, and other stakeholders to deliver comprehensive features. Write clean, maintainable, and well-tested code, and actively contribute to a culture of high quality and continuous improvement through code reviews and pair programming. Deploy and manage your services in a cloud-native environment on Google Cloud Platform (GCP) using Kubernetes and Docker. Engage with and contribute to our distributed systems landscape, helping to create resilient systems that can scale effectively. Your Qualifications Strong background in backend development with proven experience in building and delivering high-quality software. Proficiency in Node.js and TypeScript, with a deep understanding of modern backend frameworks. Hands-on experience with NestJS will be an advantage. Solid experience in designing, building, and consuming GraphQL APIs. Strong knowledge of relational databases (e.g., PostgreSQL) and data modeling practices. Hands-on experience with cloud platforms (GCP preferred) and container technologies (Docker, Kubernetes). You are a collaborative team player with excellent communication skills, comfortable working in an agile environment. Bonus Points for Experience with: ORM tools like MikroORM

Position Overview: The Quantitative Development team collaborates closely with quantitative researchers to architect, implement, deploy, and utilize cutting-edge software for research and trading purposes. As an integral part of the technology team, we embrace modern software development methodologies and work alongside peers to innovate and enhance these tools for broader applications. Quantitative developers lead cross-functional initiatives with both technologists and quantitative researchers across diverse asset classes to fulfill Squarepoint’s strategic objectives. Engage with quantitative researchers to design and construct robust and scalable workflows for research and trading. Work collaboratively with team members and technical peers to ensure global consistency and maximize the reuse of software components. Take full ownership of projects throughout their complete engineering lifecycle. Provide level 2 support for mission-critical components.