Backend Engineer - Join Our Innovative Team in Paris

About the Role airapps is looking for a backend engineer to help build and maintain the systems behind our applications. This position is based in Paris and focuses on developing backend solutions that scale and perform reliably. What You Will Do Design, implement, and maintain backend systems for airapps products Work closely with teammates to solve technical challenges Contribute to a collaborative team environment Who We’re Looking For Experience building backend systems Comfort working with others to solve problems Interest in developing efficient and scalable solutions This is a full-time role in Paris. If building reliable backend infrastructure with a team sounds appealing, airapps would like to connect.

Are you ready to take your career to the next level? Join Adaptive ML as a Backend Engineer and be part of a cutting-edge team that is transforming the landscape of machine learning. In this role, you will design, develop, and maintain scalable backend solutions that drive our innovative applications.

At Outsight, we celebrate the spirit of initiative and welcome talented individuals who wish to join our dynamic team. If you are passionate about our mission and believe your skills can contribute to our goals, we encourage you to submit a spontaneous application.To apply, please upload your resume. Our dedicated recruitment team will carefully review your submission and will reach out if a suitable opportunity arises. Thank you for considering Outsight as your future employer. We look forward to connecting with you!

About UsAt Trainline, we are passionate advocates for sustainable travel, dedicated to shaping a greener future. Our platform empowers millions of travelers to easily discover and book the most cost-effective tickets across various carriers, fares, and travel options via our highly-rated mobile app, website, and B2B partner channels.Embark on Great Journeys with Trainline As Europe's leading rail app, boasting over 125 million monthly visits and £5.9 billion in annual ticket sales, we partner with over 270 rail and coach companies across more than 40 countries. Our aim is to make travel simple, seamless, eco-friendly, and affordable for everyone.Currently a FTSE 250 company, we are fueled by a diverse team of over 1,000 individuals from 50+ nationalities, operating in cities like London, Paris, Barcelona, Milan, Edinburgh, and Madrid. With a strong focus on growth within the UK and Europe, now is the ideal time to join us on this high-speed journey.Meet the Backend Teams at Trainline Our Backend teams are the backbone of Trainline's exceptional product offering. We develop the journey search capabilities that millions of customers rely on daily, create an eCommerce platform for a secure and smooth experience, and connect with over 270 transportation operators across 45 countries worldwide. Each team specializes in various domains, including journey search, fare calculations, bookings, fulfillment, payments, refunds, carrier integrations, real-time timetable data, journey disruptions, and more.Your Role as a Mid-Level .NET Engineer at Trainline Implement new functionalities or features utilizing the most suitable tools and techniques.Prioritize quality in every aspect of your work and that of your team.Continuously enhance the codebase.Keep the customer as the top priority.Proactively identify and eliminate blockers, inefficiencies, and waste.Contribute significantly to technical decision-making.Serve as a coach and mentor for your team members.Take full ownership of the development lifecycle from coding to production, including deployment and monitoring.

Join Our Team with a Spontaneous Application!Are you passionate about innovation and eager to contribute to a dynamic team? If you don’t find an open position that aligns with your skills but are excited about the prospect of working with us, we encourage you to submit a spontaneous application using the form below. We are always on the lookout for talented individuals who can help drive our mission forward.

Note: This position is based in Paris, France. Relocation and visa support are available if necessary.Achieve the Best Work of Your CareerTrade Republic stands as Europe's largest savings platform, actively engaging in 18 countries and serving over 10 million customers who trust us with more than €150 billion in assets. Our ambition goes beyond that.Our mission is to empower individuals to build wealth through easy, safe, and free access to financial systems. Join us to advance your career while collaborating with exceptional talent and cutting-edge technology, creating a positive impact for millions.Your ResponsibilitiesDevelop and test services and products utilizing modern tools from the JVM ecosystem, including Kotlin, Spring, Vert.x, Hibernate, or jOOQ.Design cloud services with a focus on high availability, low latency, and scalability (primarily on AWS).Implement automated software delivery through GitHub Actions, container-based CI/CD pipelines, and Kubernetes orchestration.Ideal Candidate ProfileA minimum of 5 years of experience in software engineering, preferably within the JVM ecosystem. We welcome candidates from mid to staff level, so whether you are looking to take on more ownership or have extensive experience leading complex systems, we encourage you to apply.Proven experience in developing and deploying scalable features within a service-oriented architecture.A strong dedication to delivering reliable and maintainable software through an iterative development approach and continuous delivery.Experience in building platform services that serve as a foundation for product development (prior experience in platform-focused teams is advantageous).Comfortable working in a flexible hybrid environment, with 2-3 days a week in the office.Why You Should Apply NowOur culture celebrates ownership, excellence, and high energy. We prioritize outcomes and accountability as we strive to tackle one of Europe's significant challenges: closing the pension gap and democratizing wealth. If you resonate with this mission, we want to hear from you!

At Theodo HealthTech, we are continually on the lookout for exceptional talent to join our dynamic teams. If you don't find the perfect position among our current job listings, don't hesitate to reach out. We firmly believe that every unique skill set can significantly contribute to our success!

Location Alert: This position is based in Paris, France, and we offer relocation support if needed (for candidates located within the EU).TAKE YOUR CAREER TO NEW HEIGHTSAt Trade Republic, Europe’s leading savings platform, we empower over 10 million customers across 18 countries, managing assets exceeding 150 billion Euros. Join us in our mission to revolutionize access to financial systems, enabling everyone to build wealth.As part of our team, you will collaborate with talented professionals and cutting-edge technology to create a positive impact for millions.YOUR ROLEContribute your expertise to the iOS guild, ensuring technical excellence.Mentor fellow engineers and receive coaching to foster your professional growth.Take ownership of product development, collaborating across roles to guarantee quality and timely delivery.Thrive in a dynamic, goal-oriented agile environment.WHAT WE SEEK5+ years of experience in mobile engineering.Proficiency in Swift, programmatic UI design, and foundational knowledge of reactive programming.A passion for exceptional user experience (UX) and user interface (UI), with a desire to work closely with our design team.A commitment to quality, with an understanding of best practices in coding and product development.TECHNOLOGY STACK100% SwiftSwiftUI and UIKitReactive data management using Combine, ReactiveSwift, and WebSocketsMVVM-C architectureDependency InjectionWHY JOIN US?Our culture champions ownership, excellence, and energetic collaboration. We're dedicated to achieving significant outcomes, tackling one of Europe’s major challenges: closing the pension gap and democratizing wealth. If you’re excited about making a difference, we want to hear from you!

About UsAt Yubo, we are revolutionizing the way individuals connect online through our innovative Social Discovery app. By removing likes and follows, we empower our users to form authentic relationships and express their true selves.We have pioneered a fresh approach for Generation Z to engage socially in the digital realm, currently serving millions of active users. Our mission is to continuously redefine how social connections are formed now and in the future.Our team is diverse, multicultural, and passionately dedicated to our vision. As a leading platform for online socialization, we prioritize creating a safe digital environment for our community. Safety is ingrained in our values, and we proactively work on user protection, support, and education, collaborating with the tech industry and NGOs to establish best-in-class child protection standards.Join us on this exciting journey and play a vital role in shaping the future of social interactions!Role OverviewAs we expand our Tech organization for 2026, Yubo is launching a new Innovate squad dedicated to daring product initiatives and high-stakes projects.This squad aims to take bold risks, experiment with ambitious features, and validate ideas through ongoing testing.We are seeking a Senior Backend Engineer to become a key member of our Backend Experience team, reporting directly to Armand, our Engineering Manager.You will work within a multi-disciplinary squad (including Product, Mobile, Design, and Data) alongside a Senior Backend Engineer who shares leadership responsibilities.Your mission? Design, implement, and manage high-risk backend experiments that test groundbreaking product ideas while ensuring our systems remain resilient, scalable, and cost-effective throughout rapid iteration cycles.This position is not about maintenance; it's focused on building, testing, rolling back, iterating, and learning swiftly.

Matera is on the lookout for a talented Generative AI Engineer to bolster our GenAI team, focusing on the creation of cutting-edge generative AI applications. In this role, you will enhance our internal operations and contribute to the improvement of our product offerings.As part of our data team of six, you will collaborate closely with product development and operations teams to achieve our goals.Your key responsibilities will include developing large language model (LLM) agents, integrating them into our internal tools, and continuously optimizing their performance.Key Responsibilities:Develop proof of concepts (POCs) to explore the potential of applications.Measure performance metrics and optimize solutions.Build APIs and testing interfaces for application deployment.Stay updated on technological advancements.Examples of Projects:Automated systems for addressing customer inquiries (chatbots, email responses, voice agents).Internal tools that enable our customer support team to access vital information swiftly.Document processing (contracts, quotes, etc.) to automate repetitive tasks.Our Technology Stack:Python, FastAPILangchain, LanggraphLangfuseGemini, Mistral, OpenAI

Are you passionate about data and technology? Join Magellan Partners as a Data Engineer and be part of our dynamic team in Paris! In this role, you will work on designing, building, and maintaining scalable data pipelines, transforming raw data into actionable insights to drive business decisions.

About the Role airapps is looking for a Backend QA Engineer in Paris to help keep our backend systems reliable and high quality. This role works closely with engineers and product managers to improve how we build and test software. What You Will Do Develop and maintain testing frameworks for backend applications Create automated tests to catch issues early and ensure smooth releases Collaborate with team members to refine development and QA processes Help uphold quality standards so our applications meet user needs Location This position is based in Paris.

Join our dynamic team as a Backend Engineer specializing in Rust at connecthum, a pioneering AI infrastructure startup dedicated to constructing the safety and control layers for expansive AI systems.About connecthum:We are an AI-native product company focusing on AI safety and infrastructure.Supported by a diverse range of international investors.Our systems manage high volumes of AI traffic across enterprise environments.We train and fine-tune our proprietary models to ensure optimal performance and reliability.A compact yet highly skilled team that delivers rapid results.Our mission is to create the evaluation and control layer for AI systems, enabling organizations to define, test, and enforce AI behavior in real-world situations.Your Contribution:Design and implement robust Rust backend services that facilitate real-time policy enforcement.Take ownership of features from conception to deployment - including API design, database schema, and monitoring.Develop high-throughput data pipelines to manage extensive AI traffic efficiently.Enhance system performance, reliability, and observability.Collaborate across the stack as needed, prioritizing problem-solving over strict boundaries.Work closely with product, research, and ML teams to drive innovation.This role is hands-on, directly influencing how AI operates in production settings.Technical Environment:Asynchronous Rust (Tokio)Utilizing modern web frameworks such as Axum and ActixPostgreSQL for large-scale applicationsImplementing caching and event streaming architecturesBuilding high-throughput distributed systemsFocus on production observability and performance tuning(In-depth technical stack details will be shared during interviews)Your Expertise:Demonstrated production experience in developing backend systems using Rust.Strong foundation in asynchronous programming and concurrency principles.Excellent system design capabilities, including scalability, failure modes, and trade-offs.Proficient with PostgreSQL and other related technologies.

About Mistral AIAt Mistral AI, we harness the transformative potential of AI to streamline tasks, enhance creativity, and optimize learning experiences. Our cutting-edge technology seamlessly integrates into everyday workflows.We are committed to democratizing AI through high-performance, open-source solutions and state-of-the-art models. Our comprehensive AI platform is tailored to meet the diverse needs of enterprises, available both on-premises and in the cloud. Notably, our offerings include Le Chat, the AI assistant designed to elevate both personal and professional life.As a dynamic and collaborative team, we are passionate about AI's potential to create a significant societal impact. Our diverse workforce thrives in competitive environments and is dedicated to fostering innovation. With teams spread across France, the USA, the UK, Germany, and Singapore, we embody creativity, humility, and a strong team spirit.Join us in shaping the future of AI and make a meaningful impact. Discover more about our culture at https://mistral.ai/careers.Role OverviewWe are in search of enthusiastic and talented software engineers to join our team. As a Backend Engineer, you will play a crucial role in developing the core systems that power our key products: AI Studio, Le Chat, and Mistral Code. Your contributions will shape the way users and developers interact with our AI platform at scale. You’ll focus on building reliable, high-performance backend systems and APIs that cater to millions of users and developers. Your work will greatly enhance both developer and user experiences, ensuring they are engaging, efficient, and intuitive. We welcome engineers of all levels, from recent graduates to seasoned professionals, who are eager to learn, collaborate, and deliver impactful solutions.Key ResponsibilitiesDepending on your expertise, you will engage with critical components of our technology, which may include:Backend Development- Design, develop, and maintain scalable and robust backend features and APIs using modern frameworks.- Ensure high performance and reliability across our distributed systems.

About MorphoMorpho is at the forefront of Decentralized Finance (DeFi), operating a cutting-edge lending protocol that has recently garnered $50 million in funding from renowned investors, including Ribbit Capital, a16z crypto, and Coinbase Ventures. Our vision is to create an open lending network that democratizes access to the best financial terms for all. With over $10 billion in deposits, Morpho is rapidly redefining the standards of DeFi lending. We are expanding our team to solidify our position as a key player in the emerging internet-native financial ecosystem.Our MissionAt Morpho, we believe in empowering human ambition by providing open access to capital. The current financial landscape is fragmented, leaving many opportunities unseen and many individuals overpaying or entirely excluded. We strive to ensure that capital flows efficiently to where it is most needed, enabling anyone, anywhere, to access optimal terms.LocationThis role can be based in Paris or remotely (candidates located between -5 GMT and +2 GMT are encouraged to apply to ensure effective collaboration with our team).Our Work CultureWe thrive in a fast-paced environment where tackling challenging problems is the norm. As we navigate this evolving market, adaptability is crucial. We foster a culture of open communication where questioning decisions is encouraged. Our team maintains high standards while supporting each other to overcome obstacles and share knowledge. To learn more about our values, visit morpho.org/jobs.Role & ResponsibilitiesAs a Backend Engineer, you will be responsible for designing, building, and maintaining high-performance backend services and APIs that are crucial to Morpho’s user-facing features. Depending on your level of experience, you may take ownership of specific backend domains, mentor junior engineers, and contribute to cross-team initiatives.Your Responsibilities Include:Develop, deploy, and maintain backend services using TypeScript/Node and GraphQL, ensuring reliable and low-latency experiences for users.Design and optimize relational data schemas (PostgreSQL) for accuracy, performance, and maintainability.Collaborate with cross-functional teams including frontend, product, protocol, risk, and security to deliver seamless integrations.

Trade Republic Bank is looking for recent graduates to join the Backend Engineering Program in Paris. This team builds and maintains the core systems behind Europe’s leading savings platform, which serves over 10 million customers across 18 countries and manages more than €150 billion in assets. This program offers a hands-on introduction to backend engineering in a high-impact, real-world setting. Graduate engineers work alongside experienced developers who provide mentorship and support as you move from academic knowledge to building production-ready systems. What you will do Contribute to backend services using modern JVM technologies such as Kotlin, Java, and Spring Assist in designing and developing scalable, reliable systems Work with APIs, databases, and service-oriented architectures Learn to write clean, maintainable, and well-tested code Collaborate with Product and Engineering teams to deliver features for users Gain exposure to cloud infrastructure (AWS), containerization, and CI/CD pipelines Help debug, monitor, and improve system performance Gradually take ownership of well-defined technical projects Learning and growth Participants will see how backend systems are built, deployed, and scaled in a live production environment. The program is designed to help you develop practical engineering skills while contributing to projects that matter to millions of users.

As a Solutions Engineer at Adyen, you will play a pivotal role in shaping the future of payments. You will collaborate closely with our sales and product teams to deliver enhanced solutions that cater to the diverse needs of our clients. Your expertise will help us optimize our payment processing capabilities, ensuring a seamless experience for our customers.In this dynamic position, you will be responsible for understanding client requirements, providing technical support, and implementing solutions that drive success. You will have the opportunity to work with cutting-edge technology and be part of a global team that values innovation and collaboration.

About the APM Data Hub Team The APM Data Hub sits at the heart of Datadog's Application Performance Monitoring suite. This team builds and maintains a backend pipeline that processes, transforms, and routes tracing data at scale after ingestion. The pipeline supports not only APM Distributed Tracing but also a growing set of Datadog products that rely on rich trace data. Role Overview: Engineering Manager I – APM Backend Based in Paris, this role leads a distributed team of 6 engineers. The manager sets the technical direction for a platform that is central to Datadog's product ecosystem. Responsibilities include defining the roadmap for tracing data processing, making trace data accessible to internal consumers, and upholding strong engineering standards for a system that must run reliably at scale. What You Will Do Guide and support a diverse engineering team working on backend data pipelines Shape the technical vision and roadmap for trace data processing Ensure the platform meets high reliability and engineering standards Facilitate collaboration with other product teams that depend on trace data Address complex engineering challenges that affect multiple Datadog products Workplace and Culture Datadog values in-person collaboration and creativity. The company supports a hybrid work model, helping employees balance office life and personal needs.

Join us as a pivotal member of the Backend team at amo, where you'll play a critical role in shaping our infrastructure. In the initial months, you will collaborate closely with the team and gradually take charge of key components and features. At this early stage of our journey, we are in search of adaptable engineers who are eager to contribute across multiple facets of our company’s foundation.We appreciate team members who dive deeply into their areas of expertise, fostering a culture of subject matter mastery within our team. This dedication to specialization is a core expectation for every engineer.Our backend team is responsible for both server-side operations and the backbone of the client, as we believe a unified team can more effectively manage topics like networking, data modeling, management, and synchronization.As a Backend Engineer, your daily responsibilities will include:Building the FutureYou will develop robust systems designed to handle significant traffic, vast amounts of data, and an unparalleled rate of scaling. Your toolkit will include cutting-edge technologies, elegantly crafted code, and systems built for seamless horizontal scaling.Ensuring Cross-Platform CohesionBeyond server-side development, you will be involved in the enhancement and maintenance of a Rust component shared between iOS and Android. This component primarily focuses on networking, data synchronization, and data-oriented feature logic, benefiting from a single codebase. You will collaborate with mobile engineers to ensure a consistent experience across platforms and bridge the gap between mobile development and backend architecture for a cohesive user journey.Innovative Feature DevelopmentEngage in brainstorming sessions to design and implement unique features that distinguish us in the marketplace.Commitment to Continuous ImprovementWe value mutual learning and staying updated with industry trends and emerging technologies, encouraging fresh ideas and contributions to our culture of continuous improvement.Ownership of Your DomainYou will monitor analytics and manage system incidents, taking ownership of your responsibilities and proactively addressing issues and bug fixes.

About PreludeAt Prelude, we are pioneering a new standard for user onboarding and authentication in an era where trust, speed, and conversion are paramount.Our innovative solutions streamline user verification, enhancing security and efficiency while transforming authentication into a strategic advantage. Our flagship product boasts the highest price-to-conversion ratio for OTP code delivery, intelligently adapting to utilize the most effective channels in real-time—whether through optimized SMS routing or popular messaging applications like WhatsApp. Additionally, Prelude actively mitigates spam and fraud risks that traditional providers often overlook, thereby safeguarding both profit margins and user experiences.Established in 2022 and supported by prominent venture capital firms, Prelude has rapidly achieved significant market traction and robust financial health, catering to fast-growing companies throughout Europe and making strides into the US market. Authentication is merely the beginning of our journey.With a forward-thinking roadmap and a suite of market-defining products in the pipeline, we are developing a scalable trust platform that empowers businesses to effortlessly onboard users, combat fraud intelligently, and expand confidently across the globe.About Our TeamThe Prelude team consists of former Zenly professionals who have experienced the limitations of current authentication systems firsthand. While developing products that serve millions, we recognized the challenges posed by costly and unreliable SMS authentication, leading to the inception of Prelude.Currently, our team of 40 is based in Paris, dedicated to creating high-performance, secure user onboarding solutions for businesses in Europe and the US. We believe that small, highly skilled teams are more effective than large, fragmented organizations, and we prioritize impact, quality, and agility.We embrace a flat organizational structure that enhances in-person collaboration, facilitating rapid idea exchange, grounded decision-making, and full ownership of our projects.Our core values guide our daily operations:CareWe are deeply invested in our customers, our colleagues, and the quality and reliability of our products.