Junior Backend Engineer - C#

About the Role Shift Technology is looking for a Junior Backend Engineer with C# experience to join the team in Paris, France. This role focuses on building and maintaining backend systems that power the company's products. Work closely with seasoned engineers and contribute to projects that shape Shift Technology's technical direction. What You Will Do Develop and support backend components using C# Help maintain and improve existing systems Collaborate with other engineers on technical projects Location Based in Paris, France.

Role overview Alten is hiring a C++/C Development Engineer for its Rail department in Paris. The team tackles projects that shape the future of transportation, with a focus on practical engineering and collaborative problem-solving. What you will do Design, develop, and maintain software using C++ and C for rail sector projects Work alongside fellow engineers to deliver dependable technical solutions Take part in technical discussions and contribute to process improvements Requirements Keen interest in software development and transportation technology Openness to learning and adapting to new technical challenges Collaborative mindset and proactive attitude Location This role is based in Paris.

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.

airapps is hiring a Backend DevOps Engineer in Paris. This position centers on building and maintaining systems that keep backend services running smoothly and reliably. Role overview The Backend DevOps Engineer will design and implement solutions to help backend services scale and remain dependable. Collaboration with both development and operations teams is key, with a focus on improving workflows and boosting system performance. What you will do Create and maintain scalable infrastructure for backend services Work alongside developers and operations staff to streamline processes Identify opportunities to enhance system reliability and efficiency Location This role is based in Paris.

Join Fabulous Co. as a Senior Backend Engineer specializing in NodeJS and contribute to our rapid growth in the health and wellness sector. In this startup-like environment, you’ll collaborate closely with our experienced CTO to develop cutting-edge features such as marketing optimization engines and billing reports. If you’re passionate about leveraging technology to help people cultivate healthy habits worldwide, we invite you to be part of our dynamic engineering team.

Join the Voodoo TeamFounded in 2013, Voodoo is a leading technology company dedicated to creating captivating mobile games and applications with the goal of entertaining users across the globe. With a robust workforce of 800 talented individuals, we have achieved over 7 billion downloads and boast more than 200 million active users. Voodoo stands as the third largest mobile publisher worldwide by downloads, trailing only Google and Meta. Our impressive portfolio features popular titles such as Mob Control and Block Jam 3D, along with trending apps like BeReal and Wizz.Your RoleAs a Senior Backend Engineer, you will collaborate within a dynamic team of five engineers focused on enhancing our gaming backend platform. This role requires close interaction with various departments, including Core Gaming, Live Gaming, and Engineering & Data. You will contribute to our transition from Hyper-Casual to Hybrid, Casual, and Mid-Core games, playing a pivotal role in scaling our backend architecture to support new and existing titles.Your responsibilities will encompass designing scalable backend systems that serve millions of players daily. You'll partner with client developers and game designers throughout the entire process, from conceptualizing new features to their successful implementation and iteration.

Meritis seeks a C/C++ Developer in Paris to strengthen its financial markets team. This role focuses on building and enhancing applications that underpin finance operations. Key responsibilities Design, develop, and maintain software using C and C++ for financial systems Optimize application performance and resolve technical issues as they arise Work closely with colleagues from various teams to deliver effective solutions Location This position is based in Paris.

About VibeAt Vibe.co, we are revolutionizing the way brands connect with audiences in the streaming era. We envision that streaming TV transcends traditional brand awareness; it is poised to be the next major avenue for performance marketing. Our mission is to create the infrastructure that harnesses this $100 billion potential.As a leader in Audience First Streaming TV Advertising, Vibe.co empowers marketers to leverage TV as an effective growth channel. Our comprehensive solution integrates hyper-targeted audience segmentation, AI-driven insights, real-time campaign optimization, and incrementality measurement, providing brands of all sizes the accuracy and transparency they expect from social and search advertising, applied to the TV landscape.With over 10,000 trusted brands and a reach of more than 120 million households across 500+ apps and channels, Vibe.co consistently delivers an impressive average return on ad spend of 250% and a 20% lift in sales. Achieving a $100 million revenue run rate in less than two years, we are among the fastest software companies to reach this remarkable milestone.Our investors include notable firms such as Hedosophia (early backer of Spotify, Uber, and Airbnb), Elaia, Singular, QuantumLight, and Illusian, alongside angel investors like Carolyn Everson, board member of The Walt Disney Company and Coca-Cola. Nirav Tolia, CEO of Nextdoor, is also a member of our board of directors.Founded in 2022, Vibe.co is recognized as a pioneering platform in streaming TV advertising, merging the power of performance marketing akin to Meta and Google with the fast-evolving media landscape.About the RoleAs a key member of the Performance team, you will play a vital role in managing advertiser outcomes at Vibe. Your focus will be on bidding, pacing, and enhancing the prediction stack that drives these elements. You will report directly to Clément Schiano, Engineering Manager for Performance.This position has been created to address a clear roadmap and enhance execution capabilities, as well as to mitigate knowledge concentration challenges within the team. We seek an individual who can absorb, challenge, and expand upon existing expertise, going beyond simply delivering tickets.Three compelling reasons why a talented candidate would find this role appealing:

Join Mistral as a Backend Software Engineer and be part of a dynamic team that is shaping the future of cloud technology. In this role, you will be responsible for developing robust backend systems, ensuring seamless integration, and optimizing performance. Collaborate with cross-functional teams to deliver innovative solutions that meet our clients' needs.

Join the dynamic Nexthink Engineering department, where you will be an integral part of a team dedicated to developing the Collectors—advanced endpoint agents utilized by millions of employees. These Collectors play a pivotal role in extracting and interpreting vital information from operating systems, sending it to our powerful data analytics systems, and enhancing user experience by identifying and resolving issues.As a Senior Software Engineer, you will face a series of exciting challenges: • Challenge #1: Develop comprehensive and reliable solutions. • Challenge #2: Create solutions for multiple platforms, leveraging the best features from each. • Challenge #3: Ensure cross-platform compatibility wherever possible.Our engineers thrive on tackling broad, unconventional problems, refining them into actionable solutions. They continuously innovate, prototype new ideas, and measure their impact while upholding our unwavering standards of quality, performance, and security.

Shift Technology stands at the forefront of innovation in the insurance sector, harnessing the power of artificial intelligence. Our platform integrates generative, agentic, and predictive AI to revolutionize underwriting, claims management, and fraud detection, thereby enhancing operational efficiency and delivering exceptional customer experiences.With a diverse team from over 50 countries, we are united by a commitment to reshape the insurance landscape through our SaaS solutions.Our engineering team is pivotal to our success, tackling intricate challenges and collaborating across departments to deliver high-quality results.We are redefining how data influences decision-making by developing robust, scalable software and data platforms. Whether your passion lies in distributed systems, API creation, or facilitating data-driven insights, you will discover rewarding opportunities here.Our technology stack encompasses .NET Core (C#), Python, MS SQL Server, Spark, Azure Data Factory (ADF), Databricks, GoodData, Terraform, and more. We are advancing toward distributed data systems on cloud platforms, offering intriguing challenges in both batch and real-time processing.Key Responsibilities:Design and sustain scalable data models and frameworks for data access that underpin centralized databases and downstream applications.Construct and enhance ETL pipelines to ingest, transform, and integrate diverse data sources, ensuring data integrity, quality, and accessibility through tools like Apache Spark, .NET libraries, Azure Data Factory, and DBT.Engage in Agile methodologies by contributing to sprint planning, daily stand-ups, and retrospectives to ensure continuous delivery aligned with team objectives.Collaborate with product teams to translate roadmap priorities into actionable technical designs and deliverables that satisfy business and customer demands.Work closely with Data Scientists and Engineers to create frameworks that simplify customer data integration and bolster advanced analytics.Participate in code reviews, deployment activities, and monitoring to ensure high-quality production releases and seamless operation of data pipelines and frameworks.

BlaBlaCar’s Carpool Supply team in Paris works on the systems at the heart of the company’s carpooling platform. As a Backend Engineer here, the work shapes how people arrange and share rides, influencing the experience for both drivers and passengers. Role overview This position centers on developing and refining backend services that support carpooling features. The team’s efforts help ensure the platform remains reliable and easy to use as it grows. What you will do Design, build, and maintain backend services for carpooling Create solutions aimed at improving the experience for drivers and passengers Work closely with engineers and product teams to deliver systems that scale and perform reliably Location This role is based in Paris, France.

Role Overview JobTeaser is hiring a Senior Backend Engineer with strong Ruby experience to join the team in Paris. This role focuses on building and maintaining scalable backend systems that support our platform. What You Will Do Design, develop, and maintain backend solutions using Ruby Work with cross-functional teams to deliver reliable features and improvements Write high-quality code that supports a strong user experience Location This position is based in Paris.

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!

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 UsAt MARGO, our consultants focus on what truly matters: intricate projects that combine intellectual challenges with real business impact. We partner with leading players in finance, industry, and technology to design and develop 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, our Practice Manager for the past five years. Collaborating with him means benefiting from his in-depth knowledge of the firm, receiving close mentorship for your personal development, and contributing to demanding IT projects that have a significant impact on our clients.Your ResponsibilitiesJoin an international team of electronic trading experts dedicated to developing high-performance market solutions. Your tasks will include:- Designing and enhancing trading bots capable of executing complex real-time strategies.- Optimizing performance (latency, multithreading) and managing high data volumes.- Ensuring robust C# code, adhering to SOLID principles, with testing and code reviews.- Contributing to the management of Cloud infrastructures (Azure) and data security.Candidate ProfileWe are looking for a C# developer passionate about real-time systems and interested in market finance, eager to thrive in complex, high-performance environments.- Educational background: Master’s degree (engineering school or university).- Strong skills in C#, multithreading, performance optimization, and best development practices (SOLID, unit testing).- Experience in developing critical systems, processing real-time data streams; experience in finance is a plus.- Ability to solve complex technical problems and collaborate with multidisciplinary teams.- Enthusiasm for demanding environments.

Join adaptive-ml as a Backend Engineer specializing in database management and development. In this pivotal role, you will be responsible for designing, implementing, and maintaining robust backend systems that support our advanced machine learning applications. You will collaborate closely with cross-functional teams to optimize database performance, ensure data integrity, and enhance overall system functionality.

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.

BlaBlaCar’s Payment Squad is seeking a Backend Engineer based in Paris. This team plays a key role in building and enhancing the systems that process payments throughout the platform. The work ensures millions of users can complete transactions smoothly and reliably. Main responsibilities Design, develop, and maintain backend services for payment processing Collaborate with fellow engineers to create scalable technical solutions Contribute to making transactions more reliable and efficient for users Team collaboration This role involves close teamwork with experienced colleagues. Sharing ideas and tackling technical challenges together is a regular part of building and improving payment features at BlaBlaCar.

About VoodooEstablished in 2013, Voodoo is a pioneering technology company dedicated to crafting engaging mobile games and applications that aim to entertain audiences globally. With a dynamic team of 800 professionals, we boast an impressive milestone of 7 billion downloads and over 200 million active users, positioning Voodoo as the third largest mobile publisher worldwide, trailing only Google and Meta. Our diverse portfolio features hit games such as Mob Control and Block Jam, in addition to popular applications like BeReal and Wizz.Our TeamAt BeReal, we are committed to promoting authenticity in social media. By encouraging users to capture and share genuine moments, we build real connections and celebrate everyday life. Our international team, comprising over 60 members, engages more than 30 million monthly active users. With the backing of Voodoo, we are determined to scale BeReal into a leading social network that serves hundreds of millions worldwide.Your RoleAt BeReal, we have built our platform with a compact yet highly skilled technology team, and we intend to maintain this approach as we grow to accommodate hundreds of millions of users. Our commitment to speed allows us to deploy new features faster than any other established social network while we enhance our infrastructure. We operate in small, agile teams, granting each engineer significant autonomy to influence product decisions.Address thrilling technical challenges, given the unique nature of our product, which experiences user surges of millions within short timeframes.Play a vital role in developing a resilient architecture capable of accommodating massive scale as we attract new users and expand globally.Collaborate with product and engineering teams to innovate and implement new app features.Evaluate trade-offs and tackle technical challenges associated with critical backend components.Engage in code and design reviews to uphold our quality standards.Our Technology StackInfrastructure: GCP, Kubernetes, Pub/Sub, GitHub Actions, and ArgoCD.Backend: Go, Node.js (NestJS, Nx, TypeScript)Frontend: Swift (iOS), Kotlin (Android).Database: Spanner, PostgreSQL, Redis.Ideal Candidate ProfileYou possess over 5 years of experience in API development within distributed architectures.You have demonstrated expertise in Go and have a track record of developing high-volume API microservices.You are a self-motivated individual with excellent problem-solving skills and a strong desire to innovate.