Staff Full Stack Engineer

About UpflowUpflow is a pioneering provider of innovative cash collection technology designed to assist B2B enterprises in streamlining their payment processes.As a product-driven SaaS startup founded in 2018, we have earned the trust of hundreds of companies across the US and EMEA, including notable names such as Lattice, ProductBoard, and Instawork. Our growth is supported by esteemed investors including YCombinator, Hexa, and Hedosophia, along with prominent business angels from N26, Square, Mercury, Uber, and NetSuite.This role presents an incredible opportunity to engage and develop your skills within a rapidly expanding Fintech landscape and an international team.To explore more about our company culture and team, visit our careers page at www.upflow.io/careers.About the RoleJoin a small, agile team based in Paris or operating remotely, where you'll create impactful features for our users. Your responsibilities will cover a diverse array of topics including workflow automation, payment processing, and communication functionalities such as email, calls, and letters. We are committed to integrating AI into our product offerings, and you will be instrumental in establishing our AI foundations.Our development practices involve continuous deployment, with an average of 10 deployments per day. We value pragmatism, ownership, and a growth mindset within our team.Your ResponsibilitiesYour daily tasks will include:Designing and implementing complex, high-impact product features from inception to completion.Collaborating closely with product managers, designers, and fellow engineers to translate business needs into technical solutions.Delivering clean, maintainable code to production on a daily basis.Actively participating in code reviews, providing and accepting constructive feedback.Diagnosing and resolving complex product issues.Enhancing application performance and ensuring scalability.

About UpflowUpflow is a pioneering SaaS startup specializing in advanced cash collection technology designed to help B2B companies streamline their payment processes and get paid more efficiently.Founded in 2018, we have quickly gained the trust of hundreds of businesses across the US and EMEA, partnering with notable clients such as Lattice, ProductBoard, and Instawork. Our growth has been fueled by leading investors including YCombinator, eFounders, and prominent business angels from companies like N26, Square, Mercury, Uber, and NetSuite.Join us for an exciting opportunity to work within a rapidly evolving Fintech landscape in a diverse and international setting.To learn more about our team and culture, please visit our careers page at www.upflow.io/careersAbout the RoleAs a Senior Backend Engineer, you will be part of a compact and dynamic team based in Paris or working remotely, dedicated to developing impactful features for our users. Your responsibilities will encompass a variety of areas, including integrations with third-party financial systems like ERPs and billing tools, real-time data synchronization for millions of financial transactions, and managing our REST API. We prioritize data accuracy and reliability at scale, ensuring seamless financial data exchange between systems.We embrace continuous deployment (averaging 10 deployments per day) and foster a culture of pragmatism, ownership, and a growth mindset.For insights into our engineering practices, refer to this article.Your ResponsibilitiesIn your role at Upflow, you will:Design and implement complex, high-impact features from inception to completion.Work closely with the product manager and fellow engineers to convert business needs into technical solutions.Deploy clean, maintainable code to production on a daily basis.Engage in code reviews, offering and receiving constructive feedback.Diagnose and resolve intricate data and product challenges.Optimize application performance and scalability.

About Nabla Nabla brings together entrepreneurs, clinicians, and engineers with a shared goal: making clinical work more rewarding for healthcare professionals. The team partners closely with forward-thinking clinicians to build an AI assistant that streamlines documentation and supports patient care. Nabla’s platform is now trusted by over 100,000 clinicians in more than 130 healthcare organizations. With recent Series C funding of $70M, Nabla is growing its Paris-based team to develop the next wave of clinical AI. The company’s roadmap includes expanding features such as ambient listening, dictation, coding, and command tools, all aimed at improving both clinical and financial workflows. AI and Healthcare at Nabla Nabla’s rapid growth is built on three years of focused product development. The engineering team, including former Meta AI Research engineers, stays ahead of the curve in applying AI to healthcare. The company benefits from the guidance of Yann LeCun, Chief AI Scientist at Meta and Turing Award winner, who serves as an advisor. Engineering Culture Engineering at Nabla is lean, agile, and technical. Teams work across machine learning, desktop applications, and platform infrastructure to deliver AI solutions that can scale in clinical environments. How Teams Work Product development at Nabla happens in cross-functional squads. Each squad focuses on a specific product area and includes product managers, designers, engineers with varied backgrounds, and domain experts. High ownership and collaboration define the way these squads operate. Senior Full-Stack Engineers join a squad and contribute to a focused part of the product. What You Will Do As a Senior Full-Stack Engineer in the Paris office, expect to play a key role in building and scaling Nabla’s AI-powered healthcare platform. The work covers multiple layers of the platform, integrating advanced technologies to improve both user experience and operational efficiency.

Join Outsight, where our cutting-edge software transforms 3D LiDAR data into actionable insights for tracking the movement of individuals and vehicles. Our solutions are utilized by a variety of transportation hubs, including airports and train stations, as well as sports venues, road infrastructures, and industrial sites. We empower operators with precise and anonymous Spatial Intelligence data to enhance operational efficiency and ensure user safety and satisfaction. Our diverse team of experts, spanning across Paris, San Francisco, Sophia-Antipolis, and Hong Kong, is dedicated to advancing our innovative solutions. With a commercial office in Spain, we are committed to our global outreach. Discover more about us through this link: Insights about Outsight. Trusted by leading airports and train stations worldwide, our Passenger Flow Traffic Monitoring solution is a cornerstone of our offerings. Our Car Traffic Remote Monitoring product has also gained the confidence of Tier 1 clients, including BMW. Role Overview We are seeking a vital contributor to our Outsight Shift product suite. Our ecosystem encompasses real-time 3D monitoring of digital twins, live analytics, and decision support tools designed to optimize user management of people and vehicle flows. In this role, you will play a crucial part in architecting our application and frontend foundations to ensure scalability as our product capabilities expand. You will emphasize design, performance, usability, and maintainability while collaborating closely with product managers, data engineers, and scientists to deliver seamless user experiences.

About Nabla Nabla brings together entrepreneurs, healthcare professionals, and engineers to restore the joy of practicing medicine. The team collaborates closely with innovative clinicians, applying advanced machine learning to build an AI assistant that strengthens the human connection in healthcare. By streamlining clinical documentation, Nabla helps providers focus on patient care. Today, more than 100,000 clinicians from over 130 healthcare organizations use Nabla to support their daily work. With $70M secured in a recent Series C round, Nabla is expanding to advance clinical AI and improve experiences for clinicians and patients worldwide. The company is currently developing a proactive assistant with ambient listening, dictation, coding, and command features to simplify both clinical and financial workflows. AI and Product Development Over the past three years, Nabla has invested deeply in product development. The team includes former Meta AI Research engineers, working at the intersection of AI and healthcare. Nabla’s Machine Learning group leverages the latest research to unlock new possibilities for care delivery. Yann LeCun, Chief AI Scientist at Meta and Turing Award recipient, advises Nabla. Engineering at Nabla Nabla’s engineering culture is lean, agile, and technical. Teams specialize in machine learning, native desktop applications, and platform infrastructure, all focused on delivering reliable AI solutions at scale for clinical environments. Role Overview: Full-Stack Engineer (Paris Office) The Full-Stack Engineer will join a cross-functional squad, working alongside product managers, designers, engineers, and domain experts. Squads at Nabla operate with strong ownership, taking products from concept to launch together. Main Responsibilities Build and improve features for Nabla’s web and desktop products. Help design and implement back-end APIs and services.

Join our innovative team that is reshaping the future of global living.At The Flex, we envision a world where renting a home is instant, intelligent, and effortless — as seamless as booking a ride. Our ambitious goal is to enable anyone to live anywhere, anytime, without friction.Utilizing Base360.ai, our proprietary automation engine, we’re constructing the operating system for modern renting — integrating property data, orchestrating operations, and facilitating seamless stays across continents.If you are passionate about technical ownership, system architecture, and building platforms that function at real-world scale, this role places you at the heart of how millions of people move, live, and interact with the world.

About the RoleMaki is revolutionizing the field of talent acquisition and management through innovative AI-driven solutions. As a Software Engineer, you will take charge of the entire lifecycle of our AI products, ensuring their success from conception to deployment.Lead Technical Initiatives: Oversee and execute technical projects with a holistic full-stack approach, ensuring an optimal balance between speed and quality.Develop Reliable Systems: Create systems that maintain effectiveness despite unpredictable components, harnessing AI agents in real-world scenarios.Utilize Cutting-Edge Technologies: Keep our technology stack at the forefront by incorporating the latest advancements in Large Language Models (LLMs), vision models, and agent architectures.Collaborate Across Teams: Work with various stakeholders to pinpoint user challenges and engineer immediate solutions that enhance user experience.Who You AreWe seek dynamic, product-oriented full-stack engineers eager to make a significant impact and embrace ownership in a streamlined, high-performance team environment. You should be:Autonomous: A self-starter who drives projects to completion and thrives in leadership roles.Innovative: Passionate about AI technologies and keen to actively apply them in your work.Foundational: Interested in contributing to a high-growth journey by shaping our technology and culture from the ground up.Our Technology Stack:Backend:Typescript, Python, PostgreSQL, Google CloudFrontend:ReactJS, Typescript, GraphQLIf you're enthusiastic about transforming the future of AI-driven hiring, we want to hear from you!Recruitment ProcessMochi Screening: Experience our product firsthand.Interview with Hiring Manager.Coding Assessment.System Design Interview.Final Interview with the CEO.

This opportunity is exclusively available for candidates currently residing in Europe.In this role, you will ensure that Waniwani's infrastructure remains seamless and efficient at scale.We have pioneered the first insurance application within ChatGPT, and now numerous companies are eager to launch their own AI-driven storefronts using our platform. Each of these businesses requires its own MCP server, unique codebase, and tailored distribution—all functioning flawlessly, interconnected, and overseen by you.About UsWaniwani is revolutionizing the AI distribution framework for the $10 trillion services sector. We empower businesses to offer quote-based services (insurance, wealth management, etc.) directly within LLMs, where consumer decisions are increasingly being made. Envision Shopify, but tailored for services. We are constructing the foundational infrastructure for AI-native commerce.We are at the beginning of a transformative platform shift. Our launch of ChatGPT insurance resulted in $26 billion in market cap losses for the world’s largest brokers within just 48 hours. The media dubbed it "the industry's ChatGPT moment." We refer to it as Day 1.Purpose of This RoleHaving surpassed the proof of concept stage, our product is fully operational. We now need to support hundreds of clients simultaneously, each requiring their own MCP server, bespoke data pipelines, and distribution dashboards, all while ensuring the platform operates smoothly.This position presents a systems-level engineering challenge. You will be responsible for the architecture that allows Waniwani to scale from a handful of deployments to thousands. You'll work with multi-tenant infrastructure, orchestrate multiple codebases, and manage real-time data flowing through hundreds of interconnected services. One flawed abstraction could cost us months, while one well-designed abstraction could save years.We anticipate that 95% of your code will be generated by AI. Your true value lies not in typing but in discerning what to build, how to architect it, and when the AI makes errors. You will operate at a pace that integrates LLMs as a fundamental part of your engineering process, not as a gimmick. The real constraint will be your judgment, not your typing speed.Your ResponsibilitiesOversee the multi-tenant platform. Design and sustain the infrastructure that accommodates numerous MCP codebases—each independent, customizable, and all viewable from a unified interface (or MCP).Construct the data backbone. Devise the pipelines and frameworks necessary for seamless data integration and analysis.

Front builds a platform that helps businesses manage the complex demands of B2B customer operations. The product connects teams, tools, and customer conversations so companies can scale without losing the personal touch. Over 9,000 businesses use Front, including names like Uber Freight, Navan, and Stripe. Front is backed by investors such as Sequoia Capital and Salesforce Ventures, with $204 million raised. Support also comes from executives at Atlassian, Okta, Qualtrics, Zoom, and PagerDuty. The company has received recognition including Built In's 100 Best Midsize Places to Work in SF 2025, Top Places to Work by USA Today 2025, and #4 on Fortune’s Best Workplaces in the Bay Area™. The Workflows pod focuses on turning complicated processes into streamlined, automated workflows. This helps customers reach operational excellence by simplifying how work gets done. What you will do Collaborate with product managers, designers, and fellow engineers to build new solutions for the Workflows pod.

At The Flex, we envision a future where renting a home is as instantaneous, intelligent, and hassle-free as booking a ride.Our ambitious goal is to empower individuals to live anywhere, at any time, without the usual barriers.Driven by our innovative Base360.ai automation platform, we are crafting the ultimate operating system for modern rentals — seamlessly integrating property data, streamlining operations, and facilitating effortless stays worldwide.If you are passionate about web technologies, API-driven solutions, automation, and scalable operations, this is your chance to influence how millions navigate, reside, and engage with the world. What You’ll BuildAs a Full-Stack Engineer (Web & APIs), you will be responsible for designing, developing, and scaling the essential web applications and APIs that drive The Flex platform — enabling immediate bookings, smart access, automated workflows, and predictive operations.Your role will encompass all aspects of frontend design, backend development, and cloud infrastructure, transforming intricate operational hurdles into elegant, scalable, and API-centric solutions.You won’t merely deploy features.You will enhance efficiency, unlock automation, and lay the groundwork for a sophisticated, global rental network. Your MissionBuild the PlatformCreate fast, dependable, and scalable web applications and APIs that facilitate bookings, payments, availability, and guest interactions.Design API-First SystemsDevelop robust, well-documented APIs that connect Base360.ai to internal systems and external partners.Automate at ScaleConstruct event-driven services and automated workflows to eradicate manual processes across the organization.Connect the EcosystemImplement impactful integrations with partners including Airbnb, Stripe, Hostaway, and Twilio.Deploy with ConfidenceLaunch and maintain serverless infrastructure on AWS, optimized for speed, reliability, and global reach.Solve Real ProblemsAddress challenges such as real-time booking synchronization, pricing intelligence, keyless access systems, AI-driven alerts, and live operational dashboards.Build With PurposeWork closely with product, data, and operations teams to transform concepts into tangible, measurable outcomes.

Are you passionate about innovating in the tech world? Do you thrive on tackling intricate business challenges in a dynamic, collaborative, and inclusive environment? At Capital One, you will join an energetic team of innovators and problem-solvers committed to addressing genuine customer needs.We are on the lookout for Full Stack Software Engineers who are eager to integrate data with cutting-edge technologies. As part of the Capital One team, you will play a pivotal role in a significant transformation initiative.In this position, you will contribute to an enterprise-wide data management and governance application designed to oversee digital assets, including datasets, data stores, and applications across Capital One. This centralized repository will enhance the navigation, discovery, and management of digital assets, ensuring data security and compliance.

Join Labelium as a Full Stack Software Engineer Intern in the vibrant city of Paris! In this role, you will have the opportunity to work alongside a talented team of engineers, contributing to exciting projects that shape the future of digital marketing. This internship is perfect for those looking to gain hands-on experience in a dynamic environment.

About INFINIT:Founded in 2023, INFINIT is a dynamic fintech scale-up that is swiftly expanding its presence across Europe and the Americas.Our mission is to transform the future of small and medium-sized enterprises (SMEs) by placing artificial intelligence at the heart of our innovative all-in-one operating system. With banking as a foundational element, we empower small business owners and their teams to efficiently manage and enhance every facet of their operations using AI-driven solutions.By focusing on niche industries, INFINIT offers bespoke, high-value solutions while developing cutting-edge AI products that unlock substantial growth prospects for our clientele. Our global operations are poised for expansion as we aim to redefine the fintech landscape for SMEs around the world.Join us on our journey to revolutionize the SME economy and create a significant impact through innovation Position Overview:We are seeking a passionate and skilled Full Stack Software Engineer to lead our product development initiatives. This role operates on the principle that exceptional engineers do more than just code; they create impactful solutions that meet business needs. Your main task will be to connect business objectives with technical execution, translating broad goals into well-crafted, deployable features.In this role, you will be required to evaluate project requirements, adopt a product-centric approach within the engineering team, and ensure that each line of code delivers real value. The position necessitates strong software engineering skills combined with keen product insight to prioritize and implement high-impact features in a fast-paced environment.

Role Overview Prelude is looking for a Full-Stack Engineer based in Paris, France. This role involves building and maintaining both front-end and back-end features for our applications. The work touches every layer of our systems and directly shapes how users interact with our products. What You Will Do Develop new features across the stack, from user interfaces to server-side logic Maintain and improve existing code to keep applications reliable and efficient Apply software development best practices in daily work Collaborate closely with developers, designers, and product managers to deliver solutions that address real user needs Contribute to our agile development process and help the team adapt as we grow Tech and Collaboration This position offers the chance to work with modern technologies and frameworks. Teamwork is central: engineers, designers, and product managers work together to solve problems and build new features.

Join Theodo HealthTech as a Full Stack Healthcare Software EngineerSince 2009, Theodo has been at the forefront of supporting innovative companies in designing, developing, and deploying ingenious digital products. We leverage cutting-edge technology and adopt a Lean approach to create value.Our distinctive methodology is anchored in three core principles:- We have developed recognized expertise in key product design and development technologies.- At every project stage, our primary focus is creating value for our clients.- We recruit top digital talents and nurture their ingenuity through the Lean approach.Theodo has experienced exceptional growth over the past 15 years, with a team of over 700 passionate Software Engineers dedicated to continuous improvement. Our organizational structure has evolved into specialized entities focusing on specific technologies (Theodo Apps, Theodo Cloud, Theodo Data & AI) and industries (Fintech, Govtech, HealthTech, Consumer Products Goods). By 2025, Theodo aims to achieve a revenue of €100M.At Theodo HealthTech, we empower all stakeholders in the healthcare sector to develop custom digital medical devices. Our proficiency in Lean methodologies and technology, combined with a deep understanding of healthcare, enables us to create digital medical devices that integrate seamlessly into patient care pathways, such as digital therapies (DTx), virtualized clinical trials, and digitalized care pathways. Our mission is to craft products that transform the lives of their users, whether they are caregivers or patients.Your Team:You will join a vibrant tech community of over 120 Theodoers, including software engineers, tech leads, engineering managers, and architects, who share a passion for technology and innovation.

Join the Theodo Family and Be Part of Our Success StorySince 2009, Theodo has been empowering innovative companies by facilitating the design, development, and deployment of ingenious digital products, leveraging the best of technology and Lean methodologies.Our unique approach is founded on three core principles:- We have developed recognized expertise in key product design and development technologies;- At every project stage, our priority is to create value for our clients;- We attract the finest digital talents and nurture their ingenuity through a Lean approach.Theodo has experienced exceptional growth over the past 15 years, boasting a team of over 700 dedicated Theodoers, predominantly Software Engineers passionate about technology and continuous improvement. As we grow, we have structured our group into specialized entities by technology (Theodo Apps, Theodo Cloud, Theodo Data & AI) and by industry (Fintech, Govtech, Healthtech, Consumer Goods). By 2025, Theodo aims to generate €100 million in revenue.At Theodo HealthTech, our expert health entity, we support all health stakeholders in the development of tailor-made digital medical devices. Leveraging our expertise in both Lean methodologies and technology, combined with our deep understanding of health, we design and develop digital medical devices that integrate into patient care pathways (digital therapies - DTx, virtual clinical trials, digitized care pathways). Our goal is to create products that transform the lives of their users, whether they are healthcare providers or patients.Your Team:You will join a tech community of over 120 Theodoers including software engineers, tech leads, engineering managers, and architects, all driven by a shared passion for technology and innovation.

Join Altersolutions as a Senior Full-Stack Developer specializing in ReactJS and Redux. In this pivotal role, you will leverage your expertise to design and implement innovative web applications, ensuring high performance and responsiveness to user interactions. Collaborating with cross-functional teams, you will drive the entire software development lifecycle, from concept through delivery.

About UsCryptoNext Security is a pioneering deeptech startup focused on post-quantum cryptography. We empower institutions and enterprises to navigate a future where quantum computing poses a threat to existing cryptographic standards. Our collaborations span major sectors including finance, defense, and telecommunications, as we deliver state-of-the-art, quantum-safe security solutions.Your RoleIn your capacity as a Full Stack Developer, you will play a key role in advancing DISCOVERY, our innovative observability and orchestration platform tailored for post-quantum cryptography operations.You will engage with the entire technology stack — developing backend services, managing data flows, and crafting frontend interfaces — while working closely with product, backend, and infrastructure teams.Responsibilities Design, develop, and maintain comprehensive full-stack features for the DISCOVERY platform. Create modern, responsive React front-ends that integrate seamlessly with Node.js and Kafka backends. Participate in architectural discussions and propose technical enhancements in line with our long-term product vision. Backend Development & APIs Design and implement efficient REST and event-driven APIs. Ensure optimal performance, scalability, and resilience across distributed components. Collaborate with backend engineers on domain modeling, API contracts, and data flows. Data Visualization & Observability Implement advanced data visualization and monitoring features using the ELK stack (Elasticsearch, Logstash, Kibana). Integrate backend logs, metrics, and analytics into user-friendly frontend dashboards. Engineering Standards Engage in code reviews and maintain high standards of engineering excellence. Contribute to technical documentation and advocate for software craftsmanship. Adhere to the KISS, DRY, SOLID principles, and embrace pragmatic engineering methodologies (“done is better than perfect”). DevOps & CI/CD Assist in deployment workflows, CI/CD pipelines, and automation initiatives. Work within Docker/Kubernetes environments to ensure smooth delivery of applications.

As a Customer Success Manager at Upflow, you will play a pivotal role in enhancing customer satisfaction and fostering long-term relationships. You will lead our Customer Success team, ensuring that clients achieve their desired outcomes while using our innovative solutions. Your expertise in customer engagement, problem-solving, and proactive communication will be key to driving customer success and satisfaction.