Senior Backend Software Engineer - Performance

Join our dynamic team at believe as a Senior Software Engineer. In this pivotal role, you will leverage your expertise in React and Java to design and implement innovative software solutions that enhance our platform and improve user experience.Your contributions will be vital in driving our projects forward and ensuring the effective delivery of high-quality software. We are looking for a passionate engineer who thrives in a collaborative environment and is eager to tackle complex challenges.

believe is hiring a Senior Software Engineer with a focus on React and Java for its Paris office. This role centers on creating web applications that deliver effective user experiences. Key responsibilities Design and build web applications using React and Java Collaborate with colleagues across different teams to understand requirements and deliver solutions Support ongoing enhancements to software products Location This position is based in Paris.

Join Believe, a leading digital music company, as a Senior Java Software Engineer. In this role, you will contribute to designing and developing innovative software solutions that support our dynamic music platform. You will collaborate with cross-functional teams to ensure high-quality software delivery and contribute to the continuous improvement of our engineering practices.

Join our dynamic team at Altersolutions as a Senior Software Engineer specializing in Java Spring Boot. We are seeking a highly skilled and motivated individual who thrives in a fast-paced environment and is eager to take on challenging projects. In this role, you will be responsible for designing, developing, and maintaining robust software applications that meet our clients' needs.

Your Role Join our dynamic Preventive & Continuous Care Companion team as a Senior Software Engineer at Doctolib. Your expertise will be pivotal in reinforcing our commitment to being a continuous health partner for our users by crafting top-notch free and premium products that drive health goal achievement through tailored recommendations. Key Responsibilities: Collaboratively design, implement, and uphold high-quality solutions that deliver significant value to our users. Adopt best practices to sustain and elevate engineering standards and operational excellence, facilitating team member success. Proactively oversee system health within your team’s domain by measuring SLIs, defining SLOs, and enhancing alert mechanisms. Continuously expand your domain knowledge while influencing cross-team collaborations to manage dependencies and alleviate uncertainties. Offer constructive feedback during pair programming sessions to foster growth and innovation. Our Technology Landscape We utilize a unified, fully cloud-native platform that caters to web and mobile interfaces, supports multiple languages, and meets local healthcare requirements. Our focus on modular architecture allows us to create reusable components within a distributed framework. Our technology stack includes Rails, TypeScript, Java, Python, Kotlin, Swift, and React Native. We also ethically integrate AI across our products to empower both patients and healthcare professionals. Explore our AI vision here and learn about our inaugural AI hackathon here! Who You Are If you feel that this opportunity aligns with your skills and aspirations even if you don't meet every requirement, we encourage you to apply! Deep understanding of the JVM ecosystem (Java, Kotlin, Spring Boot). Familiarity with Domain Driven Design principles. Proponent of pair and mob programming methodologies. Product-oriented mindset, adept at guiding teammates in balancing business needs and technical constraints. Experience in monitoring system health and actively contributing to its enhancement.

Main ResponsibilitiesDesign, develop, and maintain backend applications using Java (Spring Boot).Define, implement, and optimize event flows on Apache Kafka (topics, partitions, performance, security).Participate in software architecture decisions and the industrialization of real-time solutions.Ensure code quality through unit tests, continuous integration, and code reviews.Contribute to the deployment and monitoring of applications (CI/CD, monitoring, support).Collaborate closely with Product, Data, and Infrastructure teams.Provide insightful suggestions for improving technical and methodological best practices.

Join the Success Story of TheodoSince its inception in 2009, Theodo has been at the forefront of helping innovative businesses design, develop, and deploy ingenious digital products, leveraging cutting-edge technology and Lean methodologies.Our distinctive approach is anchored on three core principles:- We have honed recognized expertise in key product design and development technologies;- Regardless of the project stage, delivering value to our clients is our foremost priority in every decision;- We attract top digital talent and nurture their ingenuity through a Lean approach.Theodo has experienced remarkable growth over the past 15 years, bringing together more than 700 passionate Software Engineers dedicated to technology and continuous improvement. As we expand, we have structured our teams into specialized entities focused on technology (Theodo Apps, Theodo Cloud, Theodo Data & AI) and industries (Fintech, Govtech, Healthtech, Consumer Products). By 2025, Theodo aims to achieve €100M in revenue.You will become part of Theodo Extend, a newly formed entity within Theodo, designed to meet a growing market demand: many clients wish to retain control over product management while integrating top-tier developers into their teams.In 2024, we collaborated with over 100 clients, including Carrefour, Dior, and Yves Saint Laurent, with 63 experts dedicated to these projects.Your Mission:As a Software Engineer at Theodo Extend, you will be fully integrated into a client team while enjoying the support of our community of passionate engineers. You will receive training in best practices and ongoing guidance.You will work on tasks such as:- Revamping an existing codebase to ensure reliability, maintainability, and scalability through a complete migration to a modern stack.- Deploying a V1 in a matter of weeks, even in high-pressure contexts.

Join Talan as a Senior Java Tech Lead in our dynamic Engineering & Development IT department. In this pivotal role, you will lead innovative projects, mentor a talented team of developers, and drive the adoption of best practices in software development. Your expertise in Java and leadership skills will be essential in delivering high-quality solutions that meet our clients' needs.

At Swile, we are committed to enhancing professional experiences through innovative product solutions that alleviate daily challenges and elevate employee satisfaction. Our cutting-edge offerings in Fintech, Travel, HR, and Employee Benefits serve over 5.5 million users across 85,000 companies in France and Brazil, making a significant impact on the workplace.As a Senior Software Engineer, you will play a pivotal role in problem-solving, blending creativity with technical expertise. Your focus will be on delivering high-quality solutions swiftly and effectively, addressing both business and engineering challenges with innovative strategies rather than being restricted to specific technologies.

About H H focuses on advancing superintelligence through agentic AI. The company’s mission centers on automating complex, multi-step tasks that people usually handle, aiming for AI agents to help realize the full range of human potential. H seeks talented AI professionals who care deeply about responsible and safe development, as well as technical progress in agentic systems. The culture values openness, ongoing learning, and teamwork. Every team member’s input matters here. Product Engineering at H The Product Engineering team develops H’s Enterprise Platform, which provides customers with tools and services for essential operational needs. This platform supports large-scale computer-use agents, manages complex workflows, and offers a suite for observability, troubleshooting, and evaluation. Product Engineering connects AI research with practical applications and works closely with teams across the company.

Alice & Bob is pioneering the development of the first universal, fault-tolerant quantum computer aimed at tackling some of the most challenging problems in the world. Our innovative quantum computer is based on a revolutionary type of superconducting qubit known as the Schrödinger cat qubit. Unlike traditional superconducting platforms, cat qubits possess the remarkable capability to autonomously implement quantum error correction!We are leading the quantum revolution, standing shoulder to shoulder with industry giants like Google and IBM, and we are rapidly expanding following our successful €100 million funding round in 2025 dedicated to advancing our unique technology.With over 100 talented individuals, including physicists, PhD students, engineers, and seasoned business professionals, we are united in our quest to achieve our ambitious vision. Are you ready to join us as a quantum pioneer and help reshape the future?About the Role:The Calibration Team is tasked with automating the calibrations of our Quantum Processing Unit (QPU) to maximize its performance and ensure its operational reliability. As a Senior Software Engineer within this team, you will be instrumental in architecting the automatic calibration software. You will collaborate closely with quantum scientists to develop, maintain, and enhance the calibration processes. Additionally, you will work alongside other software engineers across the organization to facilitate seamless integration of your team's software with other in-house software components.

We are seeking a talented and experienced Senior Software Engineer to join our dynamic team at believe. In this role, you will be responsible for designing, developing, and maintaining high-quality software solutions that meet the needs of our users. You will collaborate closely with cross-functional teams to understand requirements and implement innovative solutions that drive our mission forward.The ideal candidate is passionate about technology, has a strong foundation in software engineering principles, and is eager to tackle complex challenges. If you thrive in a fast-paced environment and are looking to make a significant impact, we want to hear from you!

Join our innovative team that is transforming the future of global living.At The Flex, we envision a world where renting a home is instant, intelligent, and seamless—much like booking a ride. Our mission is ambitious: to empower anyone to live anywhere, anytime, without hassle.Driven by Base360.ai, our unique automation engine, we are crafting the operating system for modern renting—integrating property data, streamlining operations, and facilitating smooth stays across continents.If you are passionate about complex systems, automation, and developing software that has real-world applications, this position offers you the opportunity to take ownership and make a significant impact. What You'll CreateAs a Senior Software Engineer, you will design, develop, and scale essential components of The Flex platform—from core services and APIs to automation workflows and real-time systems.You will work with considerable autonomy, managing problems from start to finish and directly influencing architectural decisions while remaining deeply engaged with production code.This role is for engineers who prioritize impact over meetings and take pride in constructing systems that are reliable, elegant, and scalable. Your ObjectivesDevelop Core SystemsCreate and maintain scalable services that enhance bookings, payments, availability, pricing, and guest experiences.Design Robust APIsEstablish clean, well-structured APIs that connect Base360.ai with internal tools and external partners.Automate OperationsConstruct event-driven workflows that eradicate manual tasks and unlock operational efficiencies.Deploy with AssuranceImplement and manage cloud-native infrastructure on AWS with an emphasis on reliability, security, and performance.Tackle Meaningful ChallengesEngage in real-time booking synchronization, pricing intelligence, keyless access systems, AI-driven alerts, and live operational dashboards.Collaborate for SuccessPartner closely with product, data, and operations teams to transform complex requirements into straightforward, effective systems. Ideal Candidate ProfileExtensive experience in building production systems with Node.js, React, and AWS.Solid understanding of software design principles and best practices.Proficient with CI/CD practices and tools.Strong communication skills and a collaborative mindset.

Join our dynamic team at vusiongroupsa as a Senior Software Engineer, where you'll have the opportunity to contribute to innovative projects that shape the future of technology. We are looking for a skilled professional who can bring their expertise in software development, work collaboratively with our R&D department, and drive excellence in our engineering practices.

Join Aircall, a groundbreaking AI-driven customer communications platform utilized by over 22,000 businesses globally, enhancing revenue, expediting issue resolution, and empowering customer-facing teams. We are transforming customer interactions by seamlessly integrating voice, SMS, WhatsApp, and AI into a cohesive workspace.Our growth is fueled by a core philosophy: enable teams to work smarter, not harder. With innovations like Aircall's AI Voice Agent automating routine calls, AI Assist simplifying post-call tasks, and AI Assist Pro providing real-time support, our solutions enhance productivity leading to increased revenue and swift resolutions.Headquartered in Paris, we also boast a robust North American presence in Seattle, along with teams across Madrid, London, Berlin, San Francisco, New York City, Sydney, and Mexico City. Our product has garnered a loyal customer base, and we are rapidly scaling with the backing of premier investors and a commitment to continuous AI innovation across our offerings.At Aircall, you will be part of a dynamic organization. We are ambitious, product-oriented, and execution-driven, emphasizing impactful work, swift decision-making, and genuine growth.Our Work Culture at Aircall: We are dedicated to our customers, driven by data, and focused on delivering impactful results. We value ownership, continuous learning, and thoughtful speed. If you excel in a collaborative, fast-paced environment where trust and impact are paramount, you'll thrive here.We are seeking a passionate and engaged Senior Software Engineer to enhance our expanding engineering department and contribute to our teams.As a Senior Software Engineer, you will lead the design, development, deployment, and operation of crucial features that deliver value to our customers. Your responsibilities will include ensuring operational excellence, monitoring key metrics, enhancing observability, promoting best practices, and mentoring team members across the Engineering division.Driven by quality, excellence, and agility, you will play a pivotal role in elevating our delivery processes. Utilizing NodeJS and Typescript within a robust back-end framework on AWS, you will tailor solutions to meet varied requirements.

The AI Platform is at the forefront of Datadog’s AI initiatives, encompassing everything from cutting-edge distributed training infrastructure for our state-of-the-art models to the essential frameworks that power Bits AI and LLMObs. We are on a mission to enhance our offerings beyond just model creation, focusing on the development of tools that will empower engineers to deploy production-ready generative AI systems. This includes creating retrieval-augmented pipelines, autonomous agents, and comprehensive evaluation harnesses.We are seeking a Senior Software Engineer to architect and develop this next-generation platform. You will collaborate closely with the Applied AI, product, and core infrastructure teams to deliver:Large-scale experimentation, training, deployment, and monitoring solutionsDeveloper toolchains tailored for agents and other generative AI applicationsLow-latency serving infrastructure that seamlessly integrates AI features into all Datadog productsAt Datadog, we value a vibrant office culture that fosters relationships, sparks creativity, and encourages collaboration. We operate in a hybrid work environment, allowing our employees to achieve a work-life balance that suits their individual needs.

Believe is a music company focused on supporting artists and labels. The team in Paris is looking for a Senior Software Engineer to help shape new projects and improve the digital platform. Role overview This position involves working with teams from different areas to create software that can grow with the company's needs. The work centers on building and improving products that help the music industry adapt and develop. What you will do Work closely with colleagues from various disciplines to design and develop software solutions Contribute technical expertise to projects that expand and strengthen Believe’s digital ecosystem Requirements Strong background in software development Interest in building products that support artists, labels, and the broader music industry Ability to collaborate effectively within cross-functional teams This role is based in Paris and offers the chance to contribute to projects that influence the future of music.

Join our innovative AI Operations team as an early member, dedicated to seamlessly integrating artificial intelligence throughout our organization.In the first few months, you'll collaborate closely with our founding team, gradually assuming responsibility for essential components and features. We are in search of adaptable engineers who are eager to contribute across various facets of our company's foundation during this exciting early stage.We appreciate team members who immerse themselves in their expertise, fostering a culture of knowledge and skill development. This commitment to excellence is expected of everyone on the team.As an AI Engineer, your daily responsibilities will include:Innovative Product DevelopmentWork closely with product and design teams to create and launch AI-driven features that elevate the user experience. Engineer and deploy scalable APIs and microservices that support AI operations in production while monitoring and optimizing performance, cost, and accuracy.Enhancing Developer EfficiencyDesign, develop, and maintain AI-enhanced developer tools that boost productivity, improve code quality, and refine release processes. Integrate AI-driven monitoring, code analysis, and release automation into CI/CD pipelines. Constantly assess new models, frameworks, and APIs (e.g., OpenAI, Anthropic, Hugging Face) to discover advancements that could enhance our engineering practices.Quality Assurance and AutomationAssess and incorporate AI-powered QA solutions that can automatically generate and execute test cases, identify regressions, and highlight anomalies in production. Collaborate with QA engineers to build intelligent validation pipelines that enhance test coverage, reliability, and scalability.Strategic Roadmap DevelopmentParticipate in the creation and ideation of our roadmap. Suggest new AI-driven initiatives and assist in evaluating their potential impact and complexity. Play an active role in shaping our internal standards and best practices for AI development, deployment, and measurement across the organization.

Paris | Full-time | Fluent in French & English The e-commerce landscape is evolving rapidly, yet independent brands often find it challenging to compete with the logistical efficiency of industry giants like Amazon. At Bigblue, we are dedicated to transforming this reality.Our mission is to empower brands by providing access to top-tier operational capabilities, enabling them to grow swiftly while ensuring an exceptional customer experience.Since our inception in 2018, we have developed an innovative tech-driven logistics platform that currently supports over 500 brands, ranging from rapidly expanding direct-to-consumer enterprises to globally recognized names such as MUJI, Aigle, and Cabaïa. With a talented team of 110+ employees across Paris, Madrid, and London, and our proprietary Warehouse Management System (WMS) Atlas, we are tackling logistics challenges that others shy away from — making fulfillment processes faster, smarter, and more sustainable.Backed by over $20 million in funding and trusted by the next generation of e-commerce innovators, we are experiencing rapid growth — aiming to handle 10 million orders in 2024 and embarking on ambitious enterprise expansion. The future is bright, and we’re searching for the right partners to help us lead the charge.