Senior Backend Software Engineer - Application Development

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.

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.

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 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!

xai seeks a Backend Engineer in London, UK to focus on API development. This role involves designing and building APIs that form the backbone of the company’s products and services. Key responsibilities Design and implement APIs to support xai’s solutions Collaborate with frontend developers and product managers to ensure seamless feature integration Optimize API performance and maintain reliability This position offers the chance to work closely with both technical and product teams, shaping the way xai’s services communicate and perform.

Role Overview Trustpilot is looking for a Digital Experience Manager (UX Developer) to lead the design and development of the customer-facing Help Centre and self-service ecosystem. This position sits within the Digital Customer Support team and plays a key part in shaping how customers interact with Trustpilot’s support resources. What You Will Do Own the end-to-end digital support experience for Trustpilot’s Help Centre and self-service tools. Blend front-end development with user experience design to create intuitive, effective support journeys. Implement and optimize solutions using Salesforce Experience Cloud and AI-ready frameworks. Work closely with the Digital Customer Support team to deliver on the "Smart Tools, Trusted Help" vision. Shape how customers find answers and interact with support content in a SaaS environment. Location This role is based in London. About Trustpilot Trustpilot is a profitable, high-growth FTSE-250 company operating the world’s largest independent consumer review platform. The company’s mission is to enhance trust globally by providing a space for honest customer feedback.

Corgi is an AI-driven insurance company designed for tech startups. With $108 million in funding and a licensed carrier status, Corgi is expanding into the UK and EU. The core platform runs on Django, integrates Stripe for payments, and uses AI for underwriting. Role overview The team is hiring a Backend Developer in London. This is a hands-on position for someone who enjoys building and launching products quickly. Developers who have taken projects from concept to live deployment, whether as side projects, weekend builds, or products used by real users, will feel at home here. What matters here Experience independently building and launching real-world projects Ability to deliver results in hours or days, not weeks Comfort working across the stack and adapting to new problems Openness to better ideas, even with strong technical opinions Low-ego, outcome-focused mindset Drive and energy for a rapid startup pace How the team works Decisions are made quickly, without waiting for perfection New products and improvements ship regularly, not just quarterly Ship-and-iterate approach instead of lengthy reviews High intensity expected during both launches and quieter periods Transparency is standard; decisions are made openly Internal competition pushes everyone to improve This role is for builders who want to contribute actively. Behaviors that don’t fit Office politics, avoiding responsibility, or gossip Taking feedback personally instead of using it to improve Complicating processes instead of simplifying them Missing commitments or not following through promptly How to apply Send links to your GitHub, personal website, or live projects you have launched CVs are not required Email applications to: sergio@corgi.com If you cannot show shipped work, this may not be the right fit Location and compensation Role based in London; on-site or hybrid options available Salary: £75,000 to £140,000 plus equity Compensation reflects proven shipping ability, not job titles

Join a Pioneering CompanyAt Palantir, we develop cutting-edge software that revolutionizes data-driven decision-making and operations. Our platforms empower partners to create life-saving medications, foresee supply chain challenges, locate missing individuals, and much more by connecting the right data with the right people.Role OverviewAs a Backend Software Engineer at Palantir, you will engineer scalable software that reshapes how organizations leverage data. You will actively participate throughout the product lifecycle—from ideation and design to prototyping and delivering production-ready solutions. Collaborating closely with both technical and non-technical team members, you’ll identify customers' challenges and create products that effectively address them. We promote cross-team interactions to foster the sharing of skills, context, and experiences, enabling you to gain insights into various technologies and product facets. Our engineers operate independently, making impactful decisions within a supportive community that encourages growth and development into strong technical contributors and engineering leaders.Your daily responsibilities will be dynamic, adapting to user needs and technical hurdles. One day, you might partner with other engineers to design a groundbreaking system that facilitates a new workflow; the next day, you could focus on optimizing performance for low-latency operational results.Our Product Development teams consist of small, agile groups of Software Engineers, each dedicated to specific product facets. These teams collaborate to build cross-functional capabilities, enhance user workflows, and consistently improve our software’s efficiency and reliability.We are seeking engineers who are enthusiastic about tackling real-world challenges and empowering both developers and end-users to maximize their potential. If you are driven to create reliable, high-performance, and scalable systems and to design robust APIs and primitives, this role presents a unique opportunity to significantly impact our products and the communities that utilize them.Unique Opportunity: Frontline ProgramFoundry Software Engineers may be selected for the Frontline Program, a distinct opportunity to engage directly with customers. In this short-term assignment, you will work alongside users to gain invaluable insights into product application and the challenges they encounter. Unlike standard engineering roles, Frontline involves tackling complex, ambiguous problems, empowering you to deliver impactful solutions across critical industries and institutions.

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.

Your ContributionThe Senior Software Engineer III (Backend) plays a pivotal role in tackling intricate tasks and is instrumental in advancing the objectives of their team. This role includes leading small projects or components while crafting robust feature sets that adhere to high architectural quality standards.Key ResponsibilitiesAdvanced Software Development: Actively participate in the design and implementation of sophisticated software solutions, ensuring optimal functionality, scalability, testability, and reliability. Assist with system design and grooming processes.Code Quality and Optimization: Enhance and maintain code quality through thorough review practices, optimization strategies, and adherence to industry best practices.Innovative Problem Solving: Tackle complex technical challenges with creative solutions.Collaboration and Communication: Collaborate effectively within the engineering team and across various departments, working alongside other engineers, product managers, and stakeholders.Continuous Learning and Adaptation: Stay current with emerging technology trends and continuously enhance skills and knowledge.Technical Documentation: Produce and maintain comprehensive technical documentation for clarity and accessibility.

Job Title: Engineer II Location: London / Bristol / Edinburgh (Hybrid options available) Salary: £45,600 - £62,700 Team: Developer Experience Reporting To: Senior Software Engineering Manager This position is based in the UK and candidates must possess the right to work in the UK. Currently, we are unable to offer visa sponsorship for this position. Our commitment to building a diverse, global team is paramount, and our sponsorship policy is assessed on a role-by-role basis. Please check back on our careers site for future opportunities that may include visa sponsorship. Kaluza is revolutionizing the energy sector with our Energy Intelligence Platform, simplifying the complexities of energy management. We assist energy companies in addressing contemporary challenges while propelling the transition to a sustainable, electrified future. Our platform facilitates millions of real-time decisions across households, devices, markets, and grids. By integrating predictive algorithms with user-centric design, Kaluza ensures that clean energy is reliable, affordable, and seamlessly integrates into daily life. With teams spread across Europe, North America, Asia, and Australia, and a joint venture with Mitsubishi Corporation in Japan, we empower leading companies such as OVO, AGL, and ENGIE, alongside innovators like Volvo and Volkswagen. Where will I be working? You will be part of the Developer Experience (DevEx) team within our expansive Kaluza Technology community. Our team comprises a diverse group of data-driven and product-oriented Software and Production Engineers who are at the forefront of technological innovation and operate at an impressive scale. Together, we pursue engineering excellence by implementing best practices throughout the community. In this role, you will be instrumental in designing and enhancing our Internal AI Engineering Platform. Your responsibilities will include creating the infrastructure—from Model Context Protocol (MCP) servers to collaborative workflows—that enables our software teams to operate more efficiently and securely. Your contributions will significantly influence Kaluza's ability to eradicate defects, enhance productivity, and set the benchmark for AI-driven development. Our tech stack is dynamic, and you may work with: AWS, Kubernetes, LLMs (Claude, GPT, etc.), MCP servers, LangChain/LangGraph, and contemporary monitoring tools.

Galaxy Digital Services develops digital asset solutions at the intersection of finance and technology. The company invests in data center infrastructure to support AI and high-performance computing, focusing on blockchain and digital asset innovation. With a global presence and a team led by CEO Michael Novogratz, Galaxy serves institutions, startups, and developers navigating the digital economy. What you will do This Backend Java Developer role is part of the Lending technology team in London. The position centers on building and maintaining crypto lending systems. Core responsibilities include: Developing and enhancing lending infrastructure Working on collateral management features Implementing interest calculation logic Building liquidation processes Integrating with blockchain networks and traditional financial systems Who succeeds here The team values engineers who work independently, solve complex problems, and take ownership of their projects. Analytical skills and a drive to resolve challenges are important for this position. Our core values Strive for Excellence Be Selective to Achieve Effectiveness Maintain High Alignment with Loose Coupling Engage in Transparent Disagreements Support Independent Decision-Making Build Exceptional Teams

Join Zopa as a Platform Engineer focused on enhancing developer experience! In this role, you will be instrumental in optimizing our development platform, facilitating a seamless workflow for our engineering teams. Your expertise in platform technologies will empower developers to build and innovate more efficiently.

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.

Over 500 million downloads. 80 million monthly users. A decade of relentless innovation – and we’re just getting started.Flo is the leading health & fitness app globally, dedicated to transforming the future of female health. With a $200 million investment led by General Atlantic, we proudly became the first app in our sector to achieve a $1 billion valuation in 2024. Our journey continues unabated.With 7 million paid subscribers and the highest-rated user experience in the App Store’s health category, we have spent the last decade building trust on a grand scale. Now, we are pioneering the next generation of digital health technologies – AI-driven, privacy-centered, and clinically validated – to empower our users to better understand their bodies.Your RoleThe Challenge AheadAt Flo, we’re more than just an app; we’re a thriving global community. As the number one women’s health app, we experienced 8.6 million new installs in the last month, along with a 2.8 million increase in active users.This extraordinary growth demands top-tier engineering talent. We are on the lookout for a Senior Developer Experience Engineer to join our Velocity team, which focuses on enhancing our internal platform. Your objective will be to create the foundational tools that empower our engineering teams to deploy code more efficiently, securely, and at a scale that most engineers rarely encounter.Your Mission: VelocityThe Velocity team aims to minimize friction in the development process. We see our internal developers as our primary customers. Your responsibilities will include:Simplifying Complexity: Craft intuitive tools that facilitate self-service, allowing developers to concentrate on core product logic.Standardizing Excellence: Integrate best practices, security, observability, and scalability into our core infrastructure, ensuring they are fundamental, not just afterthoughts.Your ResponsibilitiesEnhancing Developer Experience: Develop self-service tools that grant product teams the autonomy they need without compromising system stability.Platform Engineering: Design and advance our core technology stack (AWS, EKS, Terraform, Ansible).Systems Resilience: Spearhead reliability initiatives, encompassing business continuity planning and a sustainable on-call strategy.Privacy at Scale: Bolster the infrastructure for industry-leading privacy features, such as our TIME-recognized "Anonymous Mode." Observability: Deploy cutting-edge monitoring solutions (metrics, logs, tracing) to ensure swift identification and resolution of issues.

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 us at Ably, where we are at the forefront of the realtime digital experience revolution. As users engage in livestreams, receive instant financial updates, and collaborate online, we are committed to powering these experiences on a large scale.Our mission is to prioritize developers in everything we do. With a comprehensive suite of products, we enable the creation, enhancement, and delivery of powerful realtime digital experiences, handling billions of messages across millions of devices daily and serving prestigious clients such as Harness, EA, Panasonic, and HubSpot.At Ably, you will contribute to building the infrastructure and technology that will define the future of the internet. The potential here is vast, and we are eager for your expertise to help us reach new heights.About This RoleAs the Technical Lead for Developer Experience, you will co-architect the vision and strategy for our Developer Experience (DevEx). Your focus will be on transforming our dashboard, documentation platform, and control plane into an exceptional user experience. We seek a senior, hands-on engineer who is passionate about enhancing the developer journey and improving the overall user experience of the Ably platform.Your deep full-stack expertise will empower you to lead a team of five engineers, where immediate feedback is part of the process, as you and your team are the end users of the ecosystem you are creating.Day-to-Day ResponsibilitiesEnhance Developer Experience: You will take charge of how developers interact with Ably’s platform and services, collaborating with the DevEx PM to set a benchmark for the industry.Lead Technical Execution: You will guide a team of five engineers in developing customer-facing web applications and will be responsible for the technical architecture and design decisions regarding our dashboard, documentation platform, marketing website, and billing UI.Foster a Product-First Culture: You will cultivate an environment where engineers are principal stakeholders in product features, focusing on customer outcomes while challenging the conventional “feature factory” approach.Thrive in a Fast-Paced Environment: You will lead a team that works collaboratively with PMs, customers, and engineers to rapidly iterate and co-create features.