Senior Backend Developer - Node.js

Role Overview anyone-ai is seeking a Backend Developer focused on AI training. This position centers on building and maintaining backend systems that power advanced AI technologies. The work supports the development and refinement of machine learning models. What You Will Do Develop backend systems that enable AI research and model training Work closely with the AI research team to improve machine learning models Help enhance and maintain training datasets for quality and reliability Location This role is based in Germany.

Anyone AI is seeking Backend Developers to join project-based consulting work with a prominent AI research lab. This remote, part-time role centers on designing and evaluating realistic software engineering tasks for AI training, with a focus on backend systems. Role overview As a Backend Developer – AI Trainer, the position involves crafting and reviewing coding scenarios that mirror real-world engineering challenges. Typical tasks include bug resolution, feature implementation, refactoring, and test creation. The work will also require reviewing peer submissions to ensure they meet quality standards. What you will do Create and implement multi-file coding tasks, including bug fixes, new features, refactoring, and test generation. Draft clear, natural language specifications and provide reference implementations. Develop and expand unit and integration test suites. Review peer-generated tasks for accuracy, clarity, and feasibility. Identify edge cases, ambiguities, and potential failure points. Ensure specifications, code, and outputs remain consistent and aligned. Requirements Professional fluency in written English and strong communication skills. 3 to 7 years of hands-on experience in software engineering. Advanced knowledge of Python and JavaScript or TypeScript, plus working familiarity with Java, C#, or Go. Experience in backend or full-stack development in production environments. Proficiency with testing frameworks such as pytest, Jest, JUnit, xUnit, or Go testing tools. Ability to debug and work within large, multi-file codebases. Comfort with code reviews, refactoring, and production migrations. Engagement details Part-time, project-based consulting Remote work Location: Germany Expected outcomes Deliver high-quality, production-ready outputs for AI training and evaluation.

Join Anyone AI as a talented Full-Stack Developer and collaborate on groundbreaking projects with a premier AI laboratory.Qualifications:Fluent in professional written English3 to 7 years of hands-on experience in software engineeringExpertise in Python and JavaScript/TypeScript, with familiarity in Java, C#, or GoExperience in backend or full-stack development within production environmentsFamiliarity with testing frameworks such as pytest, Jest, JUnit, xUnit, and Go testingProven track record of debugging and navigating extensive codebasesExperience in code reviews, refactoring, and production migrationsEngagement: This is a part-time, project-based consultancy role.Work Type: RemoteAs a contributor, you will design and evaluate authentic software engineering tasks, focusing on bug fixing, feature development, refactoring, and test generation. Your role involves crafting intricate coding scenarios and assessing peer submissions for quality and precision.Responsibilities:Create and implement multi-file coding tasks for bug fixes, feature enhancements, refactoring, and testingProduce clear, natural-language specifications and reference implementationsExpand and maintain unit and integration test suitesReview tasks generated by peers for correctness, clarity, and realismIdentify edge cases, ambiguities, and potential failure scenariosEnsure that specifications, code, and expected outputs are alignedExpected Outcomes:Deliver high-quality, production-ready coding tasks

Anyone AI is seeking experienced software engineers in Germany for a part-time, project-based role supporting a leading AI research lab. This position centers on expert evaluation and allows for fully remote work within Germany. Key responsibilities Design and complete multi-file coding tasks, such as bug fixes, new features, refactoring, and testing Write detailed specifications in natural language and supply reference implementations Develop and enhance unit and integration test suites Review tasks created by peers for accuracy, clarity, and realism Identify edge cases, ambiguities, and potential failure points Verify alignment between specifications, code, and expected outcomes Requirements Exceptional written English 3–7 years of professional software engineering experience Strong skills in Python and JavaScript or TypeScript; familiarity with Java, C#, or Go is a plus Experience in backend or full-stack development for production systems Comfort with testing frameworks like pytest, Jest, JUnit, xUnit, or Go testing tools Advanced debugging abilities in large, multi-file codebases Background in code reviews, refactoring, and handling production migrations What success looks like Consistently delivers production-ready code and thorough documentation Work arrangement Part-time, project-based contract Remote within Germany

Join the Team at lemon.markets At lemon.markets, we are on a mission to democratize investing. We strive to provide unparalleled investment opportunities for all individuals and businesses across Europe, facilitating seamless access to capital markets. By empowering FinTechs, banks, and wealth managers with our innovative solutions, we contribute to enhancing financial well-being for their clients.lemon.markets offers a Brokerage-as-a-Service platform that simplifies digital access to capital markets through a single, robust API. Our API-first approach ensures that launching investment products is client-centric and compliant, allowing our partners to navigate the complex regulatory landscape with ease. We enable our partners to go live in weeks rather than months.Having recognized the inefficiencies within the brokerage infrastructure, we are committed to transforming how investment products are developed, making the process more affordable and less burdensome. By shielding our partners and their customers from the underlying complexities, we make investing universally accessible. We thrive on tackling challenges that others may shy away from, creating significant value in the process and attracting exceptional talent.Your Role:As a Senior Backend Engineer, you will be instrumental in shaping the backend services and architecture of our brokerage API platform, enabling companies to seamlessly integrate investment functionalities into their products. You will be responsible for owning features and services from inception to deployment within cross-functional teams, ensuring optimal performance in production environments.Your focus will encompass the Customer Lifecycle and Banking processes, ensuring our Core Platform and surrounding systems are both reliable and scalable.Our Tech Stack Includes: Python, FastAPI, AWS, and Postgres. While previous experience with different modern tech stacks is welcome, enthusiasm for working with Python is essential.Your contributions will significantly influence the development of our core platform and systems, shaping architectural decisions and impacting the business as a whole. Collaborate with a diverse team of experts to leverage your experience and help build the investment infrastructure that will serve the next 100 million retail investors in Europe.

Are you an accomplished business development professional eager to apply your expertise in the rapidly evolving field of Artificial Intelligence? If you can dedicate between 8 to 20 hours per week while managing your current commitments, we want to hear from you!At 10x.team, we specialize in connecting fractional and freelance experts with leading AI laboratories to elevate the quality of advanced AI systems.Your Role: As a Business Development Manager with a focus on AI training, your impact will be significant. You will:Refine AI-generated responses concerning business development, commercial strategy, and client relations.Assess outputs for business logic, market relevance, and practical application.Craft realistic business scenarios across various industries, including market entry strategies, partnership development, and sales processes.Analyze AI reasoning in deal qualification, client needs analysis, value proposition articulation, and closing strategies.Identify gaps or misinterpretations in market approaches, sales methodologies, or strategic recommendations.Create scenario variations from different stakeholder perspectives, such as business development manager, client decision-maker, or commercial partner.In essence, your role will involve assessing and enhancing AI-generated content to align with real-world business development practices, ensuring that our AI systems have a meaningful impact in commercial and strategic settings.

About the RoleWe are on the lookout for two highly skilled backend engineers to join our dynamic team in Berlin. You will be instrumental in advancing the development and implementation of our technology, enhancing our capacity to create core backend functionalities, and empowering other teams to utilize this backend for their projects.If you have a passion for creating exceptional products, thrive in a fast-paced environment, and are eager to contribute to the success of an ambitious startup, this is the perfect opportunity for you.Our Tech Stack:Python / FastAPIPostgreSQL / MongoDB / ElasticCloud LLM providers + bare metal GPUsGCPAs an early team member, you will assume significant responsibilities from day one, with the chance to influence our technological architecture and infrastructure.Join one of the most ambitious AI companies today, collaborating with a world-class team of experts in their fields, and experience an incredibly stimulating work environment. In This Role You WillLead the delivery of complex projects, coordinating with cross-functional teams, and ensuring timely completion of essential components.Develop a deep understanding of Reliant's vision and integrate this into your architectural and process decisions in daily operations.Offer insights to refine UI/UX concepts and assist in the planning of backend and infrastructure development.Take proactive responsibility for long-term code quality and architecture. About YouThe ideal candidate will have a proven track record in backend or full-stack development, with a focus on rapid innovation and effective systems design that supports growth opportunities for both the product and the team.To thrive in this role, you should possess the following skills and experiences:5+ years of demonstrated experience in building backend services or distributed systems.Ability to design, develop, test, and maintain backend services and APIs that support product features, including writing robust, production-quality code.Engage in system and service design; contribute to architectural discussions and make informed trade-offs regarding scalability, latency, cost, and reliability.Navigate ambiguity effectively; translate vague or high-level requirements into actionable implementation plans.Collaborate with cross-functional partners including product management, frontend, UX, data, and operations to define requirements, plan implementations, and deliver features.Ensure high code quality by writing, reviewing, and improving unit/integration tests; actively participate in code reviews.

Role Overview Sopra Steria is looking for an AI Backend Developer (m/w/d) to help build and improve AI-driven backend systems for public sector projects. This position is open to candidates across Germany (bundesweit). What You Will Do Develop and maintain backend components that power AI solutions for public sector clients Work with modern technologies to create scalable and efficient systems Contribute ideas and code that support digital transformation and better digital services for citizens About Sopra Steria Sopra Steria delivers digital solutions and consulting for public and private sector organizations. The team focuses on practical innovation and improving everyday experiences through technology.

Jobgether is seeking a Senior Node.js Backend Developer for an established partner company based in Germany. This remote-first position is part of a distributed engineering team focused on secure and scalable backend systems for digital finance services used worldwide. Role overview This role centers on designing and building backend infrastructure with Node.js, supporting real-time financial products and APIs. The team works on distributed systems that power services for customers across the globe. Developers in this position address complex technical challenges in backend architecture and performance, contributing to mission-critical services for next-generation digital finance. What you will do Design and implement backend infrastructure for real-time financial products using Node.js Develop and maintain distributed systems supporting a global customer base Tackle technical challenges related to backend architecture, scalability, and performance Collaborate with engineers in different regions to deliver reliable services Explore and evaluate new technologies to enhance products and processes Requirements Extensive experience as a Node.js backend developer, with a proven record in scalable system design and maintenance Ability to work independently and take ownership of projects Strong skills in optimizing performance and ensuring security for backend services Interest in solving complex problems and building infrastructure for global users Collaborative mindset and willingness to share knowledge within a remote team Work environment Remote-first culture with distributed teams Autonomy and ownership are encouraged Chance to contribute to the evolution of financial technology Location: Germany (remote-first)

Role overview jobgether is hiring a Backend Developer to support its Research Group under a B2B contract. This position is based in Germany and focuses on building and maintaining the backend systems that drive B2B operations. What you will do Develop and maintain backend services for the Research Group Work with cross-functional teams to improve service efficiency and reliability Contribute to ensuring backend systems meet quality standards Requirements Interest in technology and backend development Motivation to tackle complex projects Dedication to delivering reliable software solutions Contract details B2B contract arrangement Based in Germany

Anyone AI is actively seeking talented software engineers to join our team as project consultants. This role offers the opportunity to engage in innovative AI-driven projects while working remotely from anywhere in Germany.Role Overview: As a consultant, you will be responsible for designing and assessing realistic software engineering tasks, which include bug fixing, feature implementation, refactoring, and test generation. Your expertise will be pivotal in creating complex coding scenarios and reviewing submissions for quality and accuracy.

Role overview Jobgether is hiring a Senior Backend Developer with advanced Node.js experience for a partner company in Germany. This role is remote-first and centers on building and maintaining backend systems behind global digital financial products. The position involves supporting large-scale platforms that require reliability and performance. What you will do Design, develop, and maintain backend services using Node.js Enhance the platform architecture to ensure high availability and scalability Optimize API performance and strengthen infrastructure resilience Work closely with engineers in different regions as part of a distributed team Contribute to new products and feature development Address technical challenges in real-time systems, microservices, and distributed applications Requirements Proven experience as a backend developer with deep knowledge of Node.js Ability to design secure, scalable, and reliable backend solutions Comfortable in a high-performance engineering setting Demonstrates autonomy and takes ownership of work Motivated by solving complex problems with global reach Work environment Remote-first setup Collaborative and international team Emphasis on autonomy and meaningful contributions

jobgether seeks a Senior PHP Developer to join the Technology & AI Labs team in Germany. The position centers on building and maintaining PHP applications that underpin technology and artificial intelligence initiatives. Key responsibilities Design, develop, and maintain PHP applications that power technology and AI-focused projects Collaborate with colleagues from various disciplines to architect scalable systems Participate in project planning and delivery using agile methods Location This position is based in Germany.

Join 10xteam as a Tax Specialist - AI Trainer in a rewarding freelance role that allows you to work remotely. This position offers an exciting opportunity to leverage your expertise in tax regulations and AI training, contributing to innovative projects while enjoying the flexibility of working from home.

Join our dynamic team as a Backend Developer with AI Focus and play a pivotal role in shaping cutting-edge solutions that harness the power of artificial intelligence. You will be responsible for designing, developing, and maintaining backend systems that support AI-driven applications, ensuring scalability, efficiency, and performance.

Join our dynamic technology team as a Lead Software Engineer specializing in Backend Development. In this pivotal role, you will spearhead the design and implementation of backend systems, ensuring scalability and performance. You will collaborate closely with cross-functional teams to drive innovation and enhance our product offerings. If you are passionate about coding, problem-solving, and leading a team, we want to hear from you!

Please submit your CV in English and indicate your English proficiency level. Mindrift connects specialists with project-based freelance roles focused on advancing AI systems for major tech companies. Projects involve testing, evaluating, and improving AI capabilities. This is a freelance, project-based position, not a permanent job. Role overview This freelance Physics Specialist position centers on designing and validating computational physics problems for AI projects. Assignments often involve: Creating physics problems that mirror real research workflows Developing challenges that require Python programming to solve, often using libraries like Numpy, SciPy, or Sympy Ensuring problems are computationally intensive and not easily solved by hand Covering areas such as mechanics, electromagnetism, thermodynamics, and quantum mechanics Basing tasks on real research issues or practical physics applications Validating solutions using Python and standard simulation libraries Documenting problem statements clearly and providing verified solutions Requirements Degree in Physics (theoretical, experimental, or computational) or a related discipline Strong Python skills for numerical validation; experience with MATLAB, R, C, SQL, Numpy, Pandas, SciPy, or relevant libraries is a plus At least 2 years of professional experience, such as research or teaching Background in numerical simulation methods Ability to design problems reflecting real research workflows in physics Creative problem-solving across multiple physics domains Familiarity with modeling and approximation techniques Written English at C1 level or higher How projects work Apply Complete qualification steps Join a project Work on assigned tasks Receive compensation Time commitment During active project periods, tasks typically require 10–20 hours per week. Workload may fluctuate based on project needs, and there is no guaranteed minimum number of hours. Compensation Contributors may earn up to $45 per hour, depending on expertise and project complexity. Actual rates and earning potential can vary between assignments.

Toloka AI seeks a Freelance English Writer and AI Trainer to join its remote team. This contract position is open to candidates based in Stuttgart, Baden-Württemberg, Germany, but all work can be completed remotely. Role overview This role centers on supporting AI projects that require strong English writing and language abilities. The work involves both content creation and helping AI systems better understand natural language. What you will do Write and edit English-language content for use in AI training Contribute to projects aimed at improving AI's language understanding Collaborate with the Toloka AI team to achieve project objectives Location Remote work is available. The position is based in Stuttgart, Baden-Württemberg, Germany, but candidates may work from anywhere.

Grafana Labs creates open-source observability tools used by millions around the world. Companies like Bloomberg, JPMorgan Chase, and eBay depend on products such as Grafana Mimir, Grafana Loki, and Grafana Tempo to monitor and analyze their infrastructure. The team values transparency, collaboration, and purposeful work. This Senior Backend Engineer role is fully remote and open to candidates based in Germany, Spain, the UK, or Sweden. Role overview The focus of this position is the Grafana Mimir open-source project. Senior Backend Engineers join either the Query or Storage sub-team, working on distributed systems that support Grafana Cloud Metrics across major cloud providers. The main priorities are scaling, reliability, and performance for a leading metrics platform. What you will do Maintain and enhance the Grafana Mimir OSS project Work on distributed systems designed for large-scale, high-performance environments Collaborate with engineers to deliver major features and improvements Drive performance and reliability improvements based on real-world usage Write and review pull requests Create design documentation for new features and changes Contribute to release automation Participate in the on-call rotation for systems managed by your team Our culture Grafana Labs encourages openness, teamwork, and meaningful contributions. The company supports remote collaboration and values engineers who care about open-source technology and want to make a difference.