Senior Node.js Developer (FinTech Project)

🏢 Summary: Senior Software Engineer role focused on building AI-powered fintech software for receivables and debt collection. The position involves developing Node.js/NestJS backend services, scalable React applications, APIs, databases, and cloud-native Docker deployments. 🗂️ Requirements: 5+ years of professional software development experience, TypeScript proficiency, Node.js and NestJS proficiency, React application development experience, REST API development experience, GraphQL API development experience, MySQL or relational database experience, Docker and containerized application experience, Cloud platform familiarity, API communication library experience, Strong problem-solving and ownership mindset, Independent and collaborative team working ability, Excellent English communication skills 📃 Skills: TypeScript, Node.js, NestJS, React, REST, GraphQL, MySQL, Docker, Axios, GoogleCloud 🏢 Description: We are looking for a Senior Software Engineer (Node/React) to join a fast-growing European fintech company building AI-powered software that transforms how businesses manage receivables and debt collection. The platform automates financial workflows, streamlines collections, and integrates seamlessly with clients' systems, helping organizations improve cash flow through modern cloud-native technology and intelligent automation. You will play a key role in developing and maintaining backend services, building modern React applications, and contributing to cloud-native deployments. The ideal candidate enjoys solving technical challenges, takes ownership of features, and is passionate about delivering high-quality software while working with modern technologies and AI-powered solutions. Requirements 5+ years of professional software development experience Strong proficiency in TypeScript, Node.js (NestJS), and React Solid experience building modern React applications Experience developing and maintaining REST and GraphQL APIs Hands-on experience with MySQL or other relational databases Experience working with Docker and containerized applications Familiarity with Google Cloud Platform or other cloud platforms Experience using Axios or similar libraries for API communication Strong problem-solving skills with an ownership-driven mindset Ability to work independently while collaborating effectively within a team Excellent English communication skills Nice to Have Experience integrating AI services such as OpenAI APIs Experience with Tailwind CSS, Material UI (MUI), or similar UI frameworks Experience building cloud-native, serverless applications Familiarity with Agile development environments Startup experience Responsibilities Develop and maintain backend services using NestJS (Node.js) and TypeScript Build and enhance modern React applications with a focus on scalability and performance Develop and maintain REST and GraphQL APIs Integrate AI-powered capabilities into the product using modern AI services Design responsive user interfaces using Tailwind CSS, Material UI, and modern frontend technologies Manage application deployment using Docker in a cloud-native environment Design, optimize, and maintain MySQL databases and application data models Collaborate with cross-functional teams to deliver features from concept through production Participate in technical discussions, code reviews, and continuous improvement initiatives Take ownership of features while contributing to product quality, engineering best practices, and ongoing platform development

🏢 Summary: Senior Back-end Developer role focused on designing secure, reliable Node.js/TypeScript backends for real-time automated decision-making. The position involves microservices, databases, APIs, cloud deployments, automated testing, production support, and AI-assisted development in an agile international team. 🗂️ Requirements: 5+ years of Node.js, JavaScript, and TypeScript experience, Relational database experience, Microservices and system design knowledge, Test pyramid implementation experience, Security best practices, AI-assisted development tool proficiency, English proficiency, Afternoon/evening availability for cross-time-zone collaboration 📃 Skills: Node.js, JavaScript, TypeScript, PostgreSQL, MySQL, Docker, Kubernetes, AWS, Fargate, Lambda, Nest.js, Cursor, Devin 🏢 Description: Senior Back-end Developer (Node.js / TypeScript) About the Role We are looking for a Senior Back-end Developer to join our client's team. You will architect and implement robust backends, interacting with various data stores and third-party APIs to support real-time automated decision-making. Working in an agile, multinational environment, you'll have huge creative freedom and ownership over your projects while collaborating closely with Product Managers, Senior Engineers, and Architects. Key Responsibilities Architect and implement backends and their interactions with data stores and APIs. Support reliable databases and APIs for real-time automated decision-making. Deploy software using industry-standard tooling like Kubernetes clusters and AWS Lambda functions. Investigate and resolve production issues, implementing timely fixes to minimize user impact. Focus heavily on security, following Defense in Depth principles and ensuring containers are secure. Implement robust automated test suites (unit, integration, and e2e) to maintain a low failure rate. Leverage AI-assisted development tools (such as Cursor, Claude Code, or Devin) as a core part of your daily workflow to accelerate speed and quality. Requirements 5+ years of hands-on experience with Node.js, JavaScript, and TypeScript . Practical knowledge of at least one relational database system (e.g., PostgreSQL, MySQL, or SQL Server). Adept with microservices and system design patterns. Experience implementing the test pyramid and utilizing good security practices. Strong sense of ownership, independence, and the ability to clearly convey ideas across technical and non-technical teams. Comfort with AI-assisted development tools as a core part of your setup. Good command of English (written and spoken). Availability in the afternoons/evenings for occasional alignment with multinational teams across time zones. Tech Stack & Tools Backend: Node.js, TypeScript, Nest.js Cloud & DevOps: Docker, Kubernetes, AWS (Fargate, Lambda) Testing: Automated software testing (unit, integration, e2e) AI Tools: Cursor, Claude Code, Devin (autonomous AI engineer) Nice-to-Haves Familiarity with Docker/Kubernetes/AWS deployment processes. Experience with profiling and performance optimization. Experience giving high-quality feedback during code reviews.

🏢 Summary: Join an early-stage product team to design and deliver scalable, high-volume backend systems using Node.js, TypeScript, and AWS. The role offers end-to-end ownership, influence over architecture and engineering practices, and mentoring responsibilities in a hybrid Kraków setup. 🗂️ Requirements: 5+ years of production software development with Node.js and TypeScript, Practical AWS knowledge, Distributed systems design knowledge, Scalability knowledge, Event-driven architecture experience, Automated testing experience, Independent problem-solving ability, English communication skills, Ability to work in an evolving, fast-paced environment 📃 Skills: Node.js, TypeScript, AWS, Lambda, ECS, S3, RDS, Jest, Vitest, Playwright 🏢 Description: Senior Backend Engineer: Node.js & AWS Location: Kraków, Poland Working model: Hybrid Contract: Employment agreement or B2B Build high-scale systems from the beginning We’re hiring an experienced backend engineer to join a growing international technology business as it expands its engineering presence in Kraków. This is an opportunity to help create a new product rather than inherit a finished roadmap. You’ll influence early technical decisions, build systems designed for demanding workloads, and take meaningful ownership from architecture through production. The company develops robust data infrastructure used by organizations operating in complex, high-stakes environments. Its technology processes large volumes of information and supports products where speed, availability, and accuracy genuinely matter. If you enjoy solving difficult engineering problems, making pragmatic architectural decisions, and seeing your work reach production, this role offers plenty of room to make an impact. What you’ll be doing Design and deliver scalable backend services with Node.js and TypeScript. Build APIs and asynchronous, event-driven workflows in AWS. Engineer reliable systems capable of supporting intensive, high-volume workloads. Own features throughout their lifecycle, from technical discovery and design to deployment and ongoing improvement. Help establish the architecture and engineering practices of a new product. Partner with product specialists and engineers across multiple disciplines. Support other developers through mentoring, thoughtful reviews, and knowledge sharing. Strengthen standards around testing, security, maintainability, and operational reliability. Respond constructively as requirements evolve and new technical challenges emerge. What we’re looking for At least five years of professional experience building production software with Node.js and TypeScript. Strong practical knowledge of AWS. Experience with services such as Lambda, ECS, S3, or RDS is especially relevant. A solid understanding of distributed system design, scalability, and event-driven architecture. Experience using modern automated testing tools such as Jest, Vitest, or Playwright. The confidence to investigate unfamiliar problems and move work forward independently. Clear English communication skills. Comfort working in an energetic environment where priorities and products continue to evolve. Additional experience we’d value You don’t need to bring everything on this list, but any of the following would be useful: Go development. Distributed platforms or messaging-based systems. Large language models or contemporary AI development tools. React. Relational and non-relational databases. Docker and Kubernetes. CI/CD pipelines and modern delivery practices. Why consider this opportunity? Join at an early stage and help shape a product’s technical direction. Work on challenging systems where performance and reliability are fundamental. Take genuine ownership without unnecessary layers of decision-making. Become part of a new engineering group in Kraków with room to influence how it develops. Collaborate in an international, English-speaking environment. Choose between an employment contract and a B2B arrangement. Work within a hybrid model in Kraków. Join a profitable, expanding business focused on sustainable long-term growth.

🏢 Summary: Middle/Senior Full Stack Developer role focused on customer-growth features for a large-scale international platform, including onboarding, subscriptions, pricing, trials, and payments. The position emphasizes Node.js back-end development, React front-end work, cloud scalability, and cross-functional product delivery. 🗂️ Requirements: 4+ years of commercial software development experience, Strong Node.js and TypeScript back-end experience, Good React and TypeScript front-end skills, Product-oriented development experience, Cloud infrastructure and DevOps knowledge, AWS experience: EC2, ECS, RDS, S3, MySQL and Redis experience, CI/CD and infrastructure automation familiarity, Scalable system design and engineering best-practice knowledge, Upper-Intermediate English or higher 📃 Skills: Node.js, TypeScript, React, AWS, EC2, ECS, RDS, S3, MySQL, Redis, CI/CD, DevOps 🏢 Description: Join a product-focused engineering team working on customer growth initiatives that directly influence business scalability and user experience. You will contribute to the evolution of onboarding, subscription plans, pricing strategies, and payment experiences for a large-scale international platform. We are looking for a Middle/Senior Full Stack Developer with strong Back-end expertise in Node.js and solid Front-end skills in React. You will collaborate closely with Product Managers, Designers, QA Engineers, and other developers in a highly collaborative environment focused on innovation and continuous improvement. We at Sigma Software value engineering excellence, ownership, and knowledge sharing. This is an opportunity to work with modern cloud technologies, influence product decisions, and contribute to impactful solutions used by customers worldwide. Customer Our Customer is a product-focused international company developing a large-scale digital platform with a strong emphasis on customer growth and user experience optimization. The organization continuously improves pricing models, onboarding journeys, payment flows, and trial experiences to increase customer engagement and business scalability. The engineering culture promotes innovation, ownership, and close collaboration across product, design, and engineering teams. Project The project focuses on building and improving customer-facing product experiences related to onboarding, subscription management, pricing strategy, trial conversion, and payment flows. The team works in a modern cloud-based environment with high engineering standards and a strong product mindset. You will participate in feature delivery, scalability improvements, architecture discussions, and engineering initiatives aimed at increasing development efficiency and enhancing customer experience. Requirements 4+ years of commercial software development experience Strong Back-end development experience with Node.js and TypeScript Good Front-end development skills with React and TypeScript Experience working in product-oriented environments Knowledge of cloud infrastructure and DevOps practices Experience with AWS services such as EC2, ECS, RDS, and S3 Experience with relational databases and caching solutions including MySQL and Redis Familiarity with CI/CD tools and infrastructure automation practices Understanding of software engineering best practices and scalable system design Strong communication and collaboration skills Upper-Intermediate or higher English level Will be a plus Experience with Terraform, Ansible, SonarQube, GitLab CI/CD, and ELK stack Experience working with subscription-based or SaaS products Knowledge of experimentation platforms, pricing systems, or payment integrations Experience contributing to product growth initiatives and customer journey optimization Personal Profile Proactive and collaborative team player Product-minded engineer with strong ownership mentality Passionate about learning and continuous improvement Comfortable working in cross-functional international teams Open to innovation and process improvements Responsibilities Design, develop, and maintain scalable Full Stack solutions using Node.js, TypeScript, and React Collaborate closely with Product Managers, Designers, QA Engineers, and developers to deliver high-quality product features Contribute to onboarding, payment, trial, and pricing experience improvements Participate in technical discussions, architectural decisions, and solution design activities Improve system reliability, scalability, and performance within a cloud-based infrastructure Write clean, maintainable, and well-tested code following engineering best practices Participate in code reviews and knowledge-sharing initiatives Contribute to CI/CD improvements and engineering process optimization Support cross-team initiatives focused on developer experience and operational efficiency