Full Stack Developer - Java/React at Margo Group | Paris

Join our innovative team at myjobcompany1 as a Full Stack Web Developer. In this role, you will be responsible for designing and implementing robust applications that improve user experience and meet business needs. You will work with both front-end and back-end technologies, ensuring seamless integration and performance.

About UsAt CryptoNext Security, we are pioneers in the realm of deep technology, focusing on post-quantum cryptography. Our innovative solutions empower businesses and institutions to safeguard their data against the impending challenges posed by quantum computing. We proudly collaborate with prominent clients across sectors such as finance, defense, and telecommunications.Your Daily ResponsibilitiesCraft and implement dynamic user interfaces utilizing React for our advanced post-quantum cryptography products.Work collaboratively with Product and Backend teams to deliver a seamless and user-friendly experience.Enhance performance while ensuring cross-browser and cross-device compatibility.Integrate REST APIs to facilitate interaction with backend services.Engage in code reviews and uphold best practices, including unit testing, continuous integration, and comprehensive documentation.Propose enhancements to frontend architecture through technological upgrades and refactoring.Foster improvements in our products beyond your typical responsibilities.Adhere to our frontend team principles: “Done over perfect” / we prioritize speed: KISS, DRY (Don't Repeat Yourself), SOLID.Essential SkillsProficient in React / Next.js along with its ecosystem (React Hooks, Context API).Solid understanding of TypeScript and fundamental programming principles.Experience with modern UI libraries such as Tailwind or chadcn/ui.Proven track record in integrating REST APIs.Strong knowledge of frontend performance optimization and related tools (Webpack, Vite, Core Web Vitals).Familiarity with frontend testing frameworks like Jest, React Testing Library, and Cypress.Competence in Git, CI/CD pipelines, and DevOps for automated integration and deployment.Desirable SkillsExperience with gRPC.Understanding of secure coding practices and application security.Basic knowledge of cryptography and cybersecurity.Experience in a startup or deeptech environment.Join Our TeamYou will become a key member of our R&D team, collaborating closely with backend developers, product managers, and UX/UI designers. You will report to the team lead and work with various departments to develop high-performance, user-centric interfaces that align with our clients' needs.Application ProcessInitial conversation with our HR team to discuss your background and motivations.Technical interview to assess your skills and fit for the role.

UpSlide is the leading productivity and branding solution for financial services. Our innovative software significantly enhances the functionalities of PowerPoint, Word, Excel, and Power BI, enabling users from prestigious firms such as Citi, KPMG, and BNP Paribas to focus on high-value tasks rather than formatting or manual data entry. With over 160 employees, we are in a growth phase, with offices located in Paris (headquarters), London, New York, Singapore, and Berlin.Our Core Values Our values guide our approach to work and are central to our recruitment process. We seek individuals who resonate with the following principles:Excellence: Every detail matters, and we prioritize the quality of our deliverables.Trust: We are passionate, committed, and empowered to act autonomously.Well-being at Work: We maintain a positive outlook and share our enthusiasm with colleagues and clients alike.The Team ‍‍You will join the UpSlide development team, currently composed of 26 developers organized into 5 squads. Our missions for 2026 include:OfficeJS: Preparing UpSlide for the transition from Microsoft Office to Office JS.FA: Enhancing our product's superiority in the Financial Advisory sector.FA & AI: Strengthening our product's edge in Financial Advisory by focusing on AI-related solutions.IB & AM: Continuously improving our offerings for Investment Banking & Asset Management.Platform: Upgrading our infrastructure to support tenfold user growth.Join Us!

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.

Join our dynamic team at Magellan Partners as a Full Stack Java Developer! In this role, you will be responsible for designing, developing, and maintaining innovative software applications using Java technologies. You will work collaboratively with cross-functional teams to deliver high-quality solutions that meet our clients' needs.As a Full Stack Developer, you will leverage your expertise in both front-end and back-end development to create user-friendly applications. This is an exciting opportunity to enhance your skills and contribute to impactful projects in a fast-paced environment.

Join our dynamic technical team of around thirty professionals in a warm and fun work environment! You have the freedom to choose your preferred workstation setup, allowing you to work in the way that suits you best.Your day-to-day will involve tackling a diverse range of challenges, including API development, implementing new features, creating proofs of concept (POCs), and managing application maintenance (TMA).Our technology stack includes:NodeJs & ExpressJS;AngularJs, VueJs;MongoDB, Postgres;Kubernetes & Docker;AWS;

Who Are We? Safran.AI (formerly Preligens) specializes in advanced artificial intelligence solutions designed for analyzing high-resolution satellite imagery, full motion video (FMV) streams, and acoustic signals. Our innovative tools are deployed across the aerospace, defense, and governmental sectors. Since 2016, the company has been at the forefront of developing complex algorithms and software that automate the analysis, detection, and identification of military-relevant objects using both commercial and governmental data sources. As a part of the Safran group since September 2024, Safran.AI is also instrumental in transforming the group by applying AI solutions to Industry 4.0 domains. For instance, automated image analysis can assist inspectors in identifying potential anomalies in critical components from digital photographs. At Safran.AI, innovation and the pursuit of a safer world are embedded in our culture. Joining our team means collaborating with passionate, multi-disciplinary experts (engineers, researchers, developers) who are driven by a shared commitment to technological excellence. We foster a stimulating work environment where creativity and initiative are encouraged, and every idea is valued. Your Mission, Should You Choose to Accept It As a Full Stack Developer, you will be instrumental in the design and ongoing development of our product and infrastructure, primarily utilizing Python, PostgreSQL, and other cutting-edge technologies. → Design, develop, and maintain our back-end infrastructure and automated pipelines.→ Create, maintain, and evolve user interfaces (JS/CSS) for partner plugins.→ Collaborate with the team on specifications, testing, and technical best practices.→ Work closely with all teams and subject matter experts to understand end-user needs.→ Ensure high code quality for our frameworks by applying best practices and mentoring others. Technology Stack:Our development teams primarily use Python for back-end development and JavaScript (React) for front-end solutions. We also leverage Docker for deployment and SQL/PostgreSQL for database management.

Company Overview:Tessan is a fast-growing French startup specializing in telemedicine, dedicated to combating medical deserts across France. With over 1,500 devices deployed in less than six years, our mission is to ensure that every French citizen can access a doctor within 15 minutes of their home.We are expanding our team to support our product growth and accelerate our technological projects in web, mobile, data, and AI solutions. We are looking for a Full Stack Developer Intern (H/F) to join our technical team and actively contribute to the development of our digital solutions.Key Responsibilities:In a context of rapid product growth and technological innovation, you will participate in developing and enhancing our applications and services. You will collaborate with the technical team on various topics ranging from product development to optimizing our data and AI tools.1) Product Development (Web & Mobile)Engage in continuous development of the Tessan mobile and web applicationsContribute to the creation of new features (front-end & back-end)Assist in bug fixing and ongoing improvements of the applications2) Service Maintenance & ImprovementParticipate in maintaining the backend services and APIsContribute to enhancing performance and stability of servicesHelp establish best development practices (testing, code quality, documentation)3) Optimization & AutomationAssist in optimizing technical and operational processesParticipate in automating workflows (data handling, synchronization, processing)Utilize AI tools to improve productivity and development efficiency4) CI/CD, Deployment & IndustrializationContribute to improving CI/CD pipelinesAssist in deploying and industrializing new projectsHelp implement monitoring tools and service tracking5) Architecture & Technical ProjectsEngage in architectural discussions (mobile, web, backend)Enhance skills on technical choices and best development practicesContribute to data-related projects, data pipeline, and topics around Big Data and AI as projects progress6) Cross-Department CollaborationWork collaboratively with product, operations, and business teamsParticipate in technical discussions and progress meetings with the team

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.

Who are we?At MARGO, our consultants focus on what truly matters: tackling complex projects that combine intellectual challenges with real business impacts. We support major players in finance, industry, and technology in designing and developing high-performance software solutions, including distributed architectures, cloud platforms, real-time systems, and large-scale critical applications.Why join the Software Engineering Practice?You will be part of a team led by Paul Blois, Practice Manager at MARGO for five years. Working alongside them means benefiting from in-depth company knowledge, receiving close support for your career development, and contributing to demanding IT projects with significant impact for our clients.Your Responsibilities- Design, develop, and optimize a new web application for the reporting, tracking, and auditing of insiders (staff with access to sensitive information) for a major banking client.- Participate in defining and implementing a high-performing and scalable architecture.- Address performance optimization challenges in both front-end and back-end systems.- Ensure code quality, maintainability, and security of the solution.- Collaborate closely with product, security, and infrastructure teams for seamless integration.- Contribute to code reviews, continuous improvement, and the sharing of best practices.Languages: Java 17, TypeScriptAssociated frameworks and technologies: Spring Boot, Angular 12, Git, CI/CDChallenges: performance, response time optimization, robustness, and regulatory complianceDesired ProfileWe are looking for a full-stack developer who is passionate about real-time systems and interested in financial markets, eager to work in complex and high-performance environments.- Education level: Master’s degree (engineering school or university).- Strong skills in both back-end and front-end development, multithreading, performance optimization, and good development practices (SOLID, unit testing).- Experience in developing critical systems, real-time data stream processing; experience in finance is a plus.- Ability to solve complex technical problems.

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 Alten as a Full Stack Developer specializing in Vue.js and PHP Laravel. We are seeking passionate developers who thrive in innovative environments. You will work on exciting projects that challenge your skills and allow you to grow professionally.

Join CAPFI Technology - a Hub of IT and Financial ExpertiseCAPFI Technology, located in Paris and London, combines our expertise in IT and market finance. Our consultants collaborate with clients on strategic projects that integrate innovation, technology, and financial challenges. Your Responsibilities :As a .NET Developer / Software Engineer (H/F), you will be part of an agile team working with a financial market client on:Developing containerized full-stack applications and micro-services while adhering to Craftsman practices (TDD, BDD, DDD).Analyzing architecture to identify improvements.Designing and developing .NET applications.Implementing continuous integration via automated tests (Jenkins, GitLab, Bitbucket, etc.) and continuous deployment (Ansible, AWX, Octopus, GitLab, etc.).Managing versions (Git, TFS).Creating test plans and participating in tests not covered by unit tests. Your Strengths :A passion for thriving in a demanding and enriching environment.A desire to challenge yourself in client missions.Curiosity, passion, and a collaborative spirit.A strong interest in management and a willingness to mentor peers.Solid technical or functional skills in market finance.A degree from an engineering school or equivalent, with at least three years of experience in IT. What We Offer You:CAPFI is a vibrant company that places collective spirit and peer sharing at the heart of its culture. We provide a flexible work environment with agile project choices. CAPFI also offers:Freedom to choose your manager.Opportunities for certified training.The chance to join Tribes and foster the collective energy and expertise of CAPFI.

Role Overview Capimoney is hiring a Staff Full Stack Engineer in Paris. This role focuses on building and maintaining applications that improve the financial experience for users and make financial processes more efficient. The work involves both front-end and back-end development. What You Will Do Design, develop, and maintain full-stack software applications Work with teams across disciplines to deliver reliable software Contribute to projects that support client needs and business goals Collaboration This position works closely with cross-functional teams to ensure solutions are high quality and align with client requirements.

Located in the vibrant heart of Paris, Winamax is at the forefront of the online gaming industry. As a leader in poker and sports betting in France, we boast a community of 350,000 players and 600,000 monthly bettors. Our presence extends to Spain, Germany, and soon to Italy and Portugal. We are dedicated to providing our players with an exceptional experience that is technical, creative, and high-quality. Our core values of innovation, unity, and belonging foster a unique multicultural corporate culture.Imagine building your future in gaming!Technically, Winamax is:• A powerful and innovative gaming engine: dynamic adaptation of game offerings, highly configurable poker games, fraud detection.• A distributed and scalable architecture designed to handle real-time platform streams.• A modular platform that meets high availability and data security requirements, capable of managing significant traffic.ABOUT THE ROLEAs a member of our Tech team, you will play an active role in the development of the next generation of Winamax applications (desktop and mobile) and enhancing our cross-platform engine.This position is part of the Casino team responsible for developing Casino game clients (iOS, Android, Windows, Mac, Linux, Web).As a Senior Full-Stack Developer, you will be instrumental in designing, developing, and deploying our applications. Your responsibilities will include:• Developing innovative and scalable features for both front-end and back-end.• Producing robust code for real-time gambling applications.• Managing end-to-end processes: specifications, development, testing, and deployment.• Continuously improving software architecture and development best practices.

Your Responsibilities :As a Java JEE Developer / Software Engineer (H/F), you will collaborate with an agile team to drive back-end or full-stack development for one of our esteemed clients, focusing on:Analyzing architecture to ensure improvements meet expectations.Developing analytical tools for delivered components.Creating new features on a new platform compatible with current architecture.Automating testing procedures.Additionally, you will be involved in:User demonstrations.Integration testing.Production delivery (coordinating with infrastructure and security teams).Web and server development (NGINX, Apache, Tomcat, ...).Production and operational deployment procedures.Continuous integration (Jenkins, GitLab, Bitbucket, ...).Continuous deployment (Ansible, AWX, Octopus, GitLab, ...).Creating and participating in test cases.

Sopra Steria is seeking a Java Full Stack Developer to join its team in Paris, focusing on projects within the financial services sector. This position centers on building and maintaining applications that support the changing requirements of clients in finance. Role overview This role involves contributing to the design and development of software solutions using Java and related technologies. Projects aim to address real-world challenges faced by financial institutions. What you will do Develop and enhance full stack applications for financial services clients Collaborate with team members to deliver solutions that align with client needs Apply technical expertise to ensure applications are reliable and effective Requirements Experience with Java development Ability to work on both front-end and back-end components Interest in financial services projects Based in or able to work in Paris, Île-de-France

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.

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.