Senior Back End JS Developer

🏢 Summary: Senior Full Stack Engineer role focused on building and scaling core platform functionalities within a cross-functional product team. The position involves end-to-end ownership of features, from design to deployment, using a modern TypeScript-based stack on AWS. The engineer will develop scalable microservices and frontend components that support millions of global users. 🗂️ Requirements: 7+ years of professional software engineering experience, Strong hands-on experience with TypeScript, Node.js, and React, Proven experience with AWS services: API Gateway, Lambda, ECS, SQS, SNS, Experience designing event-driven and microservices architectures, Proficiency with NoSQL and relational databases, Experience with CI/CD pipelines and Docker, Experience with observability and monitoring tools 📃 Skills: TypeScript, Node.js, React, AWS, APIGateway, Lambda, ECS, SQS, SNS, MongoDB, DynamoDB, PostgreSQL, Jenkins, GitLabCI, GitHubActions, Docker, CloudWatch, Datadog, REST, Microservices, NoSQL, CICD 🏢 Description: Salary range: B2B - up to 43 E/h + VAT 💰 Ciklum is looking for a Senior Full Stack Engineer to join our team and work directly with our partner, Trustpilot, in Poland. We are a custom product engineering company that supports both multinational organizations and scaling startups to solve their most complex business challenges. With a global team of over 4,000 highly skilled developers, consultants, analysts and product owners, we engineer technology that redefines industries and shapes the way people live. About the client: Trustpilot is on an incredible journey to become the universal symbol of trust. As the world’s largest independent consumer review platform, they bring consumers and businesses together to foster transparency and improvement. With over 300 million reviews and 64 million monthly active users, the work we do together has a massive global impact, helping millions of people make better choices every day. About the role: As a Senior Full Stack Engineer, become a part of a cross-functional development team engineering experiences of tomorrow. As the world’s largest independent consumer review platform, they bring consumers and businesses together to foster transparency and improvement. With over 300 million reviews and 64 million monthly active users, the work we do together has a massive global impact, helping millions of people make better choices every day. In this role - you are fully integrated into feature teams. You will work on core platform functionalities that drive product-led growth, managing the critical customer lifecycle including sign-up, onboarding, sales, and retention. Your work will influence the experience of over 60 million monthly Trustpilot users globally! You will join a cross-functional "full ownership" team where you have a say in the direction of projects and technological choices. Responsibilities: Collaborative Development: Work alongside Product, Design, and Data Science in a team that owns its product and codebase from end-to-end End-to-End Ownership: Participate in every stage of the lifecycle—from ideation and design to architecture, implementation, deployment, and maintenance System Design: Drive technical decision-making and build scalable backend services and clean, reusable frontend components using TypeScript Scale & Innovation: Build and maintain RESTful APIs and distributed cloud services within an event-driven microservices architecture Team Leadership: Support and inspire your colleagues with your technical expertise and a problem-solving mindset Requirements: Experience: 7+ years of professional experience in software engineering Core Tech: Strong, hands-on expertise with TypeScript, Node.js, and React AWS Infrastructure: Proven experience with API Gateway, Lambda, ECS, SQS, SNS Architecture: Deep understanding of event-driven and microservice architectures Databases: Proficiency with NoSQL (MongoDB, DynamoDB) and Relational databases (PostgreSQL) DevOps & Tooling: Experience with CI/CD (Jenkins, GitLab CI, GitHub Actions), Docker, and observability tools like CloudWatch or Datadog What`s in it for you? Remote Collaboration: Enjoy the flexibility of remote work or join us in our offices across Europe Human Connection: We value a great atmosphere and host team F2F workshops a few times a year to brainstorm and bond in person Continuous Growth: Benefit from a tailored education path, including internal meetups, a Udemy license, and company-paid certifications Comprehensive Care: We offer medical insurance, mental health programs, and a welcoming, open culture Global Reach: Your work will build solutions used by millions to promote trust and transparency online Be bold, not bored! If you're ready to build the heart of trust with a world-class engineering team, we’d love to see your application.

🏢 Summary: Full-time Senior JavaScript Engineer role focused on building and evolving a scalable Design System for a global consumer platform. The position involves owning complex frontend features, creating reusable UI components, and ensuring accessibility and high-quality architecture. You will work cross-functionally with UX and product teams to deliver robust, documented, and versioned frontend solutions. 🗂️ Requirements: 5+ years frontend web development experience, Advanced proficiency in React, Advanced proficiency in TypeScript, Advanced proficiency in CSS, Experience building scalable libraries or modular UI components, Experience with Design Systems, Knowledge of WCAG 2.1/2.2 accessibility standards, Experience with versioned code libraries and release management, Upper-intermediate English proficiency 📃 Skills: JavaScript, React, TypeScript, CSS, Next.js, SASS, Playwright, Node.js, MongoDB, AWS, CI/CD, WCAG, Figma 🏢 Description: Salary range: B2B - 40-43 E/h + VAT 💰 Ciklum is looking for a Senior JavaScript Engineer to join our team full-time in Poland. We are a custom product engineering company that supports both multinational organizations and scaling startups to solve their most complex business challenges. With a global team of over 4,000 highly skilled developers, consultants, analysts and product owners, we engineer technology that redefines industries and shapes the way people live. About the role: As a Senior JavaScript Engineer, become a part of a cross-functional development team engineering experiences of tomorrow. You will join a high-impact Design Systems team alongside other Senior Engineers to own high-impact workstreams and cross-functional partnerships. Our goal is to provide a seamless experience for millions of users on a global consumer review platform through robust, documented, and accessible UI patterns. You will operate with high autonomy, turning initial product needs into reusable components that enable product teams to move faster and more consistently. Responsibilities: Feature Ownership: Take end-to-end ownership of complex system features such as Data Visualization suites, theme engines, or complex search/filtering patterns System Architecture: Build for flexibility and reusability, ensuring features solve problems for multiple product teams without creating maintenance bottlenecks UX Collaboration: Work in close partnership with UX designers to bridge the gap between Figma and code, ensuring technical feasibility during design reviews Product Integration: Act as the dedicated technical point of contact for product areas to identify patterns that should be integrated into the core library Accessibility Standards: Own the accessibility (A11y) for your features, ensuring components meet WCAG 2.1/2.2 standards Release Management: Manage the lifecycle of features within a versioned code library, ensuring safe releases and clear migration paths Technical Documentation: Produce clear, comprehensive documentation so that stakeholders, engineers, and AI agents can understand and extend your work Mentorship: Participate in code reviews and RFCs, providing constructive feedback to help other engineers grow while maintaining a high quality bar Requirements: Core Expertise: Advanced, hands-on proficiency with React, TypeScript, and CSS Frontend Experience: 5+ years of professional experience in frontend web development Systems Thinking: Proven experience building scalable libraries, shared infrastructure, or modular UI components Inclusivity: Strong understanding of building accessible interfaces and applying WCAG standards Strategic Execution: Ability to take vague requests, break them down into manageable tracks, and deliver at a steady, predictable pace Communication: Upper-intermediate or higher level of spoken and written English Desirable: Design Systems: Proven experience contributing to a professional Design System or a major open-source project Modern Tooling: Experience with Next.js, CSS Modules, SASS, or Styled Components Testing: Familiarity with end-to-end testing frameworks like Playwright Infrastructure: Understanding of AWS cloud infrastructure or CI/CD practices Backend: Exposure to Node.js, MongoDB Personal skills: Accountability: You take ownership and follow through on your responsibilities Drive: You're proactive and results-oriented, always seeking better ways to solve problems Self-development: You stay curious, seek feedback, and aim for continuous improvement Effective communication: You communicate your ideas clearly and collaborate effectively in a team Mentoring: You're open to helping less experienced team members and sharing knowledge What`s in it for you? Strong community: Work alongside top professionals in a friendly, open-door environment Growth focus: Take on large-scale projects with a global impact and expand your expertise Tailored learning: Boost your skills with internal events (meetups, conferences, workshops), Udemy access, language courses, and company-paid certifications Endless opportunities: Explore diverse domains through internal mobility, finding the best fit to gain hands-on experience with cutting-edge technologies Flexibility: Enjoy flexibility – full remote working possibilities Care: We’ve got you covered with company-paid medical insurance, mental health support, and financial & legal consultations About us: At Ciklum, we are always exploring innovations, empowering each other to achieve more, and engineering solutions that matter. With us, you’ll work with cutting-edge technologies, contribute to impactful projects, and be part of a One Team culture that values collaboration and progress. With delivery centers in Wrocław and Gdańsk, our 300+ professionals in Poland drive forward-thinking solutions for global clients. Join a community where collaboration sparks innovation—and your impact reaches millions. Want to learn more about us? Follow us on Instagram , Facebook , LinkedIn . Explore, empower, engineer with Ciklum! Interested already? We would love to get to know you! Submit your application. We can’t wait to see you at Ciklum.

🏢 Summary: B2B Full Stack Engineer role focused on building and scaling core platform functionalities within a product-led growth environment. The position involves end-to-end ownership of features, developing scalable backend services and reusable frontend components in a cloud-based microservices architecture. You will work on high-impact systems supporting millions of global users. 🗂️ Requirements: 4+ years of professional software development experience, Strong hands-on experience with TypeScript, Strong hands-on experience with Node.js, Strong hands-on experience with React, Experience with AWS services (S3, ECS, Lambda), Experience with event-driven architecture, Experience with microservices architecture, Proficiency with MongoDB and DynamoDB, Proficiency with PostgreSQL, Experience with Docker, Experience with CI/CD pipelines, Familiarity with observability tools (CloudWatch or Datadog) 📃 Skills: TypeScript, Node.js, React, AWS, S3, ECS, Lambda, MongoDB, DynamoDB, PostgreSQL, Docker, CI/CD, CloudWatch, Datadog, REST, Microservices 🏢 Description: Salary range: B2B - 30.5 E/h + VAT 💰 Ciklum is looking for a Full Stack Engineer to join our team and work directly with our partner, Trustpilot, in the Poland. We are a custom product engineering company that supports both multinational organizations and scaling startups to solve their most complex business challenges. With a global team of over 4,000 highly skilled developers, consultants, analysts and product owners, we engineer technology that redefines industries and shapes the way people live. About the client: Trustpilot is on an incredible journey to become the universal symbol of trust. As the world's largest independent consumer review platform, they bring consumers and businesses together to foster transparency and improvement. With over 300 million reviews and 64 million monthly active users, the work we do together has a massive global impact, helping millions of people make better choices every day. About the role: As a Full Stack Engineer, you will be part of a cross-functional team with full ownership of the product and codebase. In this role, you are fully integrated into Trustpilot's feature teams. You will work on core platform functionalities that drive product-led growth, managing the critical customer lifecycle including sign-up, onboarding, sales, and retention. Your work will influence the experience of over 60 million monthly Trustpilot users globally! You will join a cross-functional full ownership team where you have a say in the direction of projects and technological choices. Responsibilities: Collaborative Development: Work alongside Product, Design, and Data Science in a team that owns its product and codebase from end-to-end End-to-End Ownership: Participate in every stage of the lifecycle: from ideation and design to architecture, implementation, deployment, and maintenance System Design: Participate in technical decision-making and build scalable backend services and clean, reusable frontend components using TypeScript Scale & Innovation: Build and maintain RESTful APIs and distributed cloud services within an event-driven microservices architecture Team Excellence: Contribute to planning, troubleshooting, and code reviews while inspiring the team with your problem-solving mindset Requirements: We are looking for engineers who are passionate about high-quality code and technical excellence: Experience: 4+ years of professional experience in software development Core Tech: Strong, hands-on expertise with TypeScript, Node.js, and React AWS Infrastructure: Experience with S3, ECS, Lambda Architecture: Familiarity with event-driven and microservice architectures Databases: Proficiency with NoSQL (MongoDB, DynamoDB) and Relational databases (PostgreSQL) DevOps & Tooling: Familiarity with Docker, CI/CD pipelines, and observability tools like CloudWatch or Datadog Desirable: Hands-on experience with AWS services: SQS, SNS, API Gateway, CloudWatch Understanding of Infrastructure as Code (e.g., CloudFormation) Experience with GCP services like BigQuery Exposure to other languages (Python, .NET, or PHP) and frontend styling (SASS, Styled Components) Experience with end-to-end testing using Playwright What`s in it for you? Remote Collaboration: Enjoy the flexibility of remote work or join us in our office locations across Europe Human Connection: We value a great atmosphere and host team F2F workshops a few times a year to brainstorm and bond in person Continuous Growth: Benefit from a tailored education path, including internal meetups, a Udemy license, and company-paid certifications Comprehensive Care: We offer medical insurance, mental health programs, and a welcoming, open culture Global Reach: Your work will build solutions used by millions to promote trust and transparency online Be bold, not bored! If you're ready to build the heart of trust with a world-class engineering team, we'd love to see your application.

🏢 Summary: Full-time Software Engineer role focused on building secure, scalable backend systems and APIs on AWS using TypeScript. The position involves end-to-end ownership of automated systems that detect misuse and enforce platform policies, working across the full development lifecycle. Ideal for engineers passionate about backend stability, cloud architecture, and high-quality code. 🗂️ Requirements: 3+ years of professional backend development experience, Strong proficiency in JavaScript, TypeScript, and Node.js, Experience building and consuming RESTful or GraphQL APIs, Experience with core AWS services (Lambda, SQS, SNS, API Gateway, S3), Experience with Docker containerization, Experience with NoSQL or relational databases, Understanding of web security principles and best practices, Upper-intermediate or higher English level 📃 Skills: JavaScript, TypeScript, Node.js, AWS, Lambda, SQS, SNS, APIGateway, S3, REST, GraphQL, Docker, MongoDB, DynamoDB, PostgreSQL, Security, CI/CD, Jenkins, GitLab, GitHubActions, React, CloudWatch, Datadog, .NET, Python, GCP, BigQuery 🏢 Description: Salary range: B2B - 30 E/h + VAT 💰 Ciklum is looking for a Software Engineer to join our team full-time in Poland. We are a custom product engineering company that supports both multinational organizations and scaling startups to solve their most complex business challenges. With a global team of over 4,000 highly skilled developers, consultants, analysts and product owners, we engineer technology that redefines industries and shapes the way people live. About the role: As a Software Engineer, you will be part of a cross-functional team with full ownership of the product and codebase. You will join a team specifically focused on businesses, building automated systems that detect misuse and enforce platform policies. You will participate in all stages of the development lifecycle: from ideation and design to implementation, deployment, and maintenance. This role is ideal for an engineer with a strong passion for backend stability and scalability who enjoys building robust cloud architectures. Responsibilities: Develop and maintain secure, scalable APIs and services on AWS using TypeScript Write clean, efficient, and testable code for both backend and frontend applications Collaborate closely with senior engineers, product managers, and designers to translate requirements into technical solutions Implement security best practices in your code to protect user data and ensure platform integrity Contribute to the entire development lifecycle, from planning and implementation to deployment and maintenance Troubleshoot, debug, and upgrade existing software to enhance functionality and performance Participate actively in code reviews, providing and receiving constructive feedback to maintain a high-quality codebase Requirements: 3+ years of professional experience in backend development Strong proficiency with JavaScript, TypeScript and Node.js Experience building and consuming RESTful or GraphQL APIs Experience with core AWS services (e.g., Lambda, SQS, SNS, API Gateway, S3) Familiarity with containerization using Docker Experience with NoSQL (e.g., MongoDB, DynamoDB) and/or relational (e.g., PostgreSQL) databases A good understanding of web security principles and best practices Strong problem-solving skills and a passion for writing quality code Upper-intermediate or higher level of spoken and written English Desirable: Hands-on expertise with React Familiarity with CI/CD practices and tools (e.g., Jenkins, GitLab CI, GitHub Actions) Experience with monitoring and logging tools (e.g., CloudWatch, Datadog) Working experience with .Net or Python is a plus Experience with GCP and services like BigQuery Personal skills: Accountability: You take ownership and follow through on your responsibilities Drive: You're proactive and results-oriented, always seeking better ways to solve problems Self-development: You stay curious, seek feedback, and aim for continuous improvement Effective communication: You communicate your ideas clearly and collaborate effectively in a team Mentoring: You're open to helping less experienced team members and sharing knowledge What`s in it for you? Strong community: Work alongside top professionals in a friendly, open-door environment Growth focus: Take on large-scale projects with a global impact and expand your expertise Tailored learning: Boost your skills with internal events (meetups, conferences, workshops), Udemy access, language courses, and company-paid certifications Endless opportunities: Explore diverse domains through internal mobility, finding the best fit to gain hands-on experience with cutting-edge technologies Flexibility: Enjoy flexibility – full remote working possibilities Care: We’ve got you covered with company-paid medical insurance, mental health support, and financial & legal consultations About us: At Ciklum, we are always exploring innovations, empowering each other to achieve more, and engineering solutions that matter. With us, you’ll work with cutting-edge technologies, contribute to impactful projects, and be part of a One Team culture that values collaboration and progress. With delivery centers in Wrocław and Gdańsk, our 300+ professionals in Poland drive forward-thinking solutions for global clients. Join a community where collaboration sparks innovation—and your impact reaches millions. Want to learn more about us? Follow us on Instagram , Facebook , LinkedIn . Explore, empower, engineer with Ciklum! Interested already? We would love to get to know you! Submit your application. We can’t wait to see you at Ciklum.

🏢 Summary: Senior Backend Developer role focused on building scalable, cloud-native microservices using TypeScript and Node.js in AWS environments. The position involves designing secure backend solutions, developing IAM services, implementing test automation, and deploying distributed systems in a CI/CD setup. Work includes close collaboration within agile teams on modern, serverless architectures. 🗂️ Requirements: Minimum 5 years backend/full stack development experience, Strong experience with TypeScript and NodeJS, Experience with Java or Python, Experience designing microservices and distributed systems, Hands-on experience with AWS serverless services, Experience with automated testing including integration and E2E tests, Experience with CI/CD pipelines, Knowledge of OAuth2, OIDC, JWT, Experience with Infrastructure as Code, Fluent Polish and English 📃 Skills: TypeScript, NodeJS, Java, Python, AWS, Lambda, APIGateway, DynamoDB, EventBridge, S3, SNS, SQS, Microservices, OAuth2, OIDC, JWT, Jest, Postman, Playwright, GitLab, Kubernetes, CDK, Terraform, Serverless, CI/CD 🏢 Description: 🚀 Senior Backend Developer Location: Kraków, Poland Experience: 5+ years Contract: B2B, Full-Time Join the Future of Digital Tech with Kolomolo At Kolomolo , we don’t just follow trends - we set them. As a global supplier of IT services and digital modernization solutions, we help businesses embrace cutting-edge technology to optimize their operations. Now, we are growing and looking for fresh talent to grow with us. Are you proactive, tech-savvy, and eager to build your career in IT? This role could be your perfect fit. About the Role We’re looking for a Senior Backend Developer who enjoys building reliable, scalable, and modern cloud-native applications. In this role, you’ll be responsible for backend feature development, system modernization, test automation, code refactoring, and production deployments. You’ll work on distributed systems and microservice-based architectures while contributing to the design and development of secure and high-performing backend solutions. This role is ideal for someone who combines strong technical expertise with a collaborative mindset and enjoys working in agile, engineering-driven environments. What You’ll Be Doing Develop microservices based on Typescript & NodeJS for core business components. Design and develop company’s internal IAM microservice, preparing for a migration on a new solution. Design and develop cloud native applications based on AWS services like Lambda, API Gateway, DynamoDB and EventBridge. Creating and running automated tests, particularly integration tests and end-to-end tests for the backend layer. Work closely with Architects & SRE to follow security & reliability standards while being  actively involved in architectural discussions. Work with external partners & vendors while developing various integrations. Collaborate with the team and drive it while ensuring high code quality and standards. Be actively involved in designing and developing reliable & secure backend features/functions. Work with continuously delivered (CI/CD), asynchronous and distributed systems Tech stack Runtime: Serverless (Lambda, API Gateway, EventBridge) Backend: NodeJS / Typescript (additional Java or Python) Persistency: DynamoDB, S3, SNS, SQS Architecture: Microservices IAM: oAuth2, OIDC Connect, JWT, OPAL CI/CD: GitLab QA: Playwright/ Postman/ Jest Infrastructure: AWS, Kubernetes, AWS CDK, Terraform What We Are Looking For Min. 5 years of experience as a backend/full stack developer, with recent projects in TypeScript & NodeJS and other backend programming language (preferably Java or Python). Experience in creating and running test automation with holistic approach including system, performance smoke and E2E tests (full testing pyramid) on Jest/Postman/Playwright. Ability to share your knowledge, experiences, and opinions on the forum via technology demos/brainstorming sessions. Willingness to grow and learn with a passion for creating new solutions. Experience in working closely with product and design teams as well as doing pair programming in small, agile, and cross-functional teams. Ability and openness to work in a team, especially within a culture of mutual respect and continuous feedback. Being a Team Player, able to help people to grow and guide decision-making processes. Open minded, communicative and focused on delivering business value . Fluent verbal and written skills in Polish and English. Nice to Have Familiarity with Customer Identity Access Management systems & solutions (CIAM), ideally with proven record in designing and implementing. Experience in Infrastructure as a code especially Terraform/ AWS CDK. Developing & maintaining team’s monitoring dashboards in Grafana stack (Prometheus, Looki). What is in It for You Competitive salary and benefits. Career development opportunities in a growing tech company. Continuous learning culture: mentorship, internal training, and certifications. Flexible, agile work environment (remote, hybrid, or on-site in Kraków). Office perks: great coffee, tea, fresh fruit, snacks, and a fun atmosphere. Flat management structure, where your voice matters. Regular team events and a social, supportive work culture. Independent Contractor. 🌟 Why Join Kolomolo? At Kolomolo , we prioritize innovation, agility, and autonomy. Our teams have the freedom to own their work, share ideas, and make meaningful contributions. Inspired by Scandinavian values , we believe in work-life harmony and creating an inclusive culture where everyone thrives. You will be part of a passionate, skilled, and friendly team that works hard and celebrates together. Here, you can build your career on your own terms, with opportunities to grow, learn, and make a real impact. Our Flat Structure & The Culture of Inclusion At Kolomolo, we break the corporate mold. We offer: Agile Teams & Autonomy : No micromanagement. You’ll own your projects and enjoy the freedom to innovate. Work-Life Harmony : Inspired by Scandinavian values, we prioritize balance and flexibility, where remote work and asynchronous collaboration are in our DNA. Learning & Growth : Continuous learning is at our core. We reward hard work, value smart ideas, and foster an environment of mutual respect and trust. Inclusive Culture : We believe in DEI: diversity, equity and inclusion. We are committed to creating an environment where every individual, regardless of background, identity, or experience feels valued, respected, and empowered to thrive. Join Kolomolo and elevate your career with cutting-edge technology, a supportive team, and a company that truly values your input. Ready for the next step? Apply now and start an exciting journey of growth and innovation with us!

🏢 Summary: Backend Tech Lead role focused on leading and implementing a strategic rewrite of a core financial platform module into a modern, scalable architecture. The position combines hands-on Java/Spring Boot development with architectural decision-making, API design, and integration across multiple enterprise banking systems. It involves designing high-performance backend services handling large transactional and reporting datasets. 🗂️ Requirements: 7+ years backend or fullstack development experience, Strong Java expertise, Strong Spring Boot expertise, Experience designing REST APIs, Experience as Tech Lead or technical owner, Experience designing scalable and distributed systems, Strong relational database design skills (PostgreSQL), Experience with Elasticsearch or similar search technology, Experience integrating external systems via REST or GraphQL, Experience with Docker and Kubernetes, Experience with CI/CD pipelines, Knowledge of OAuth2 and OIDC, Working knowledge of React, Working knowledge of TypeScript, Experience handling large datasets with complex queries, Ability to lead architecture and mentor developers 📃 Skills: Java, Spring, SpringBoot, REST, GraphQL, PostgreSQL, Elasticsearch, Docker, Kubernetes, CI/CD, OAuth2, OIDC, React, TypeScript, SQL, Microservices, DistributedSystems 🏢 Description: Our client is an international financial technology company building solutions that support transaction communication, balances visibility, reporting, and integrations across multiple banking systems . We are looking for a Backend Tech Lead to join a strategic rewrite of a core platform module. The role combines technical leadership with hands-on backend development , helping redesign a legacy component into a modern, scalable architecture. You will work closely with product stakeholders, platform engineers, and frontend teams to design and implement reliable, high-performance backend services that integrate multiple enterprise systems. IN SHORT: 🌍 Remote work or on-site (Wrocław, Bielsko-Biała) – your choice! 💰 170 - 190 PLN/h + VAT ☑️ B2B contract Your Daily Missions Lead the design and development of backend services for a core platform rewrite. Design scalable services responsible for transactions, balances, statements, and reporting data . Define API contracts and integration patterns between backend services, frontend applications, and external enterprise systems. Make key decisions around data modeling, search/indexing strategies, and performance optimization for million-row datasets with complex filtering, sorting, and pagination . Support frontend teams by ensuring API-first design and smooth integration with React applications . Ensure engineering quality through code reviews, architecture discussions, and mentoring other developers . Collaborate closely with product, frontend, and platform teams to deliver robust, production-ready systems . The Essentials We're Seeking 7+ years of experience in backend or fullstack software development. Strong expertise in Java and Spring Boot , including designing modular backend services and REST APIs. Experience acting as a Tech Lead or technical owner responsible for architectural decisions. Solid experience designing scalable APIs and distributed systems . Strong understanding of data modeling in relational databases (e.g., PostgreSQL) and designing efficient query patterns. Practical experience with Elasticsearch (or similar search/indexing technologies) for filtering, search, and aggregation over large datasets. Experience designing hybrid data architectures combining multiple data sources . Experience working with external system integrations , including REST or GraphQL APIs. Familiarity with containerized environments (Docker, Kubernetes) and modern CI/CD pipelines. Understanding of security patterns in enterprise systems (OAuth2, OIDC, authentication and authorization flows). Working knowledge of React and TypeScript , enabling effective collaboration with frontend teams. Proven ability to break down complex architectural changes into manageable development phases . Experience using AI-assisted development tools (e.g., Cursor, Claude Code, or similar agentic coding tools) and openness to experimenting with AI-driven approaches to improve development efficiency and engineering workflows . Ability to combine hands-on engineering with technical leadership and mentoring . Nice-to-Haves Experience in FinTech, banking, or enterprise integration platforms . Experience with large-scale transactional or reporting systems . Experience with GraphQL integrations . Experience with data migration or legacy system modernization . Experience designing API-first platforms . Familiarity with observability practices (logging, metrics, tracing). Understanding of database partitioning and query optimization patterns . Reasons Why You Would Enjoy Working With Us We work in the latest technologies and with international clients, and our projects are polished from < to /> - learn about some of the projects we have completed. We organize TechTalks, meet-ups and create guilds where we exchange knowledge - you can learn a lot from your teammates. We have a close-knit team and we make sure to have regular integrations - we often go out to celebrate together. You can work remotely or choose to work from our offices in Wroclaw or Bielsko-Biala. However, we count on your openness to occasionally visit the office for team meetings or client visits, or possible occasional trips to the client's headquarters. You can adjust your working hours to suit your needs, starting your day between 7:00 and 10:00 am. You can work with great specialists in their fields who also have a sense of humor and other after-hours hobbies. It is the people who create the unique atmosphere and relaxed atmosphere at CSHARK. We have a flat structure - we are not a corporation and don't want to be one 🙃. We offer bonuses for employee referrals (from 3000 PLN to 7000 PLN). We organize remote English classes and provide access to the company library. You can also become an author/author of articles published on our technical blog - https://cshark.com/blog/ .

🏢 Summary: Full-time Senior Back-End Engineer (Node.js) role focused on designing and maintaining scalable, high-performance server-side applications and APIs for modern, data-driven platforms. The position involves building RESTful services, integrating with third-party systems, ensuring code quality through testing, and optimizing system reliability and performance. Hybrid work model in Warsaw with B2B or CoE contract options. 🗂️ Requirements: Strong experience with Node.js, Strong experience with Express.js, Experience building and integrating APIs (GraphQL or REST), Knowledge of OAuth, JWT, and session-based authentication, Experience with MySQL, Experience with PostgreSQL, Experience writing unit tests with Chai and Mocha, Experience using Git and version control systems 📃 Skills: Node.js, Express.js, GraphQL, REST, OAuth, JWT, MySQL, PostgreSQL, Chai, Mocha, Git 🏢 Description: Senior Back-End Engineer (Node.js) 💰 Salary: 18,700-20,900 PLN/Month 💻 Warsaw, Poland (Hybrid - 3 days in office, 2 days remote) 🕦 Full-time ☑️ B2B or CoE We’re looking for a Senior Back-End Engineer to join a fast-growing international tech company focused on building modern, data-driven platforms that power digital transformation in the financial and enterprise sectors. Requirements: Strong experience in building server-side applications using Node.js and Express.js. Hands-on experience with API development and integration, particularly with GraphQL or RESTful services. Strong knowledge of authentication and authorization mechanisms (OAuth, JWT, session-based). Strong experience with databases such as MySQL and  PostgreSQL. Experience writing unit tests with tools such as Chai and Mocha. Strong experience using Git and version control systems. Proficiency in English (both written and spoken). Nice To have: Bachelor’s degree in Computer Science or a related field. Experience with cloud platforms (AWS, Azure, or GCP), as well as containerization and orchestration tools such as Docker and Kubernetes. Experience with microservices architecture. Experience setting up CI for static analysis and test execution. Experience developing RAG applications and storing data in vector embeddings. Key Responsibilities: Design, build, and maintain scalable, high-performance server-side applications and RESTful APIs using Node.js and Express.js. Guide and supervise the development of key code components to ensure long-term reliability and scalability. Integrate with front-end components and third-party services. Actively review the codebase, recommending and implementing refinements where needed. Write unit and integration tests and optimize performance to ensure high-quality code. Collaborate closely with cross-functional teams to define and implement technical solutions. Improve system performance, reliability, and long-term maintainability through optimization and best practices. Get to know DevsData: We are a technology consulting company and a recruitment agency, delivering software solutions to clients from Europe and the US. We work 100% remotely, in an international team, including people from Asia, London, or San Francisco. We employ people with experience in international corporations as well as students of the best technical and business universities. Find out more: https://devsdata.com/

🏢 Summary: Full-time, 100% remote Senior Frontend Developer role focused on building and scaling complex, responsive web applications powered by AI-driven platforms. The position involves architecting high-quality front-end solutions, integrating with back-end services, and ensuring performance, scalability, and cross-browser compatibility. The role also includes driving best practices, code quality, and modern front-end standards within the team. 🗂️ Requirements: Strong knowledge of HTML5, CSS3, JavaScript (ES6), Strong understanding of DOM, Experience with React.js, Experience with Material UI, Experience with Responsive Design and cross-browser compatibility, Familiarity with SASS or LESS, Understanding of BEM methodology, Knowledge of CSS-in-JS, Knowledge of browser storage (cookies, localStorage, sessionStorage), Proficiency with npm or yarn, Experience with Jest or equivalent testing frameworks, Understanding of SEO best practices, Familiarity with TypeScript, Knowledge of SSR and service workers, Experience with Webpack, Vite, or Rollup, Understanding of browser extensions integration 📃 Skills: HTML5, CSS3, JavaScript, ES6, DOM, React, MaterialUI, SASS, LESS, BEM, CSS-in-JS, cookies, localStorage, sessionStorage, npm, yarn, Jest, TypeScript, SSR, Webpack, Vite, Rollup, SEO, ServiceWorkers 🏢 Description: Senior Frontend Developer (100% remote) 💰 Salary: 20,000-23,000 PLN/month 🌎 100% Remote 🕦 Full-time position ☑️ B2B or Contract of Employment We are looking for a Senior Frontend Developer for a partner client that helps businesses use artificial intelligence to run more efficiently and grow faster. The company builds and provides digital platforms and consulting services that enable organizations to manage operations, analyze data, and improve performance. Their solutions combine AI, automation, and deep business expertise to help clients simplify workflows, gain insights, and deliver greater value. Requirements: HTML5 , CSS3 , JavaScript (ES6) Strong understanding of the Document Object Model (DOM) Skilled in Responsive Design and cross-browser compatibility Experience with React.js and Material UI Familiarity with CSS preprocessors such as SASS or LESS Understanding of BEM methodology and CSS-in-JS approaches Knowledge of browser storage mechanisms (cookies, localStorage, sessionStorage) Proficient in using package managers (npm/yarn) Experience in unit testing using Jest or equivalent frameworks Understanding of SEO best practices Familiarity with TypeScript for type-safe, large-scale applications Knowledge of server-side rendering (SSR) and service workers Experience with code bundling and modern module bundlers (e.g., Webpack, Vite, Rollup) Understanding of browser extensions and their integration with web applications Responsibilities: Develop and maintain  complex, responsive user interfaces for large-scale web applications. Architect and integrate front-end components with back-end APIs and services , ensuring security, scalability, and performance. Drive the implementation of pixel-perfect UI/UX designs across browsers and devices. Provide technical mentorship to junior developers and guide the team in adopting modern best practices. Conduct code reviews , enforce standards, and maintain a clean, modular codebase. Evaluate and recommend new frameworks, tools, and libraries to enhance productivity. Manage project timelines, estimate development efforts, and collaborate effectively with cross-functional teams. Maintain comprehensive front-end documentation , design patterns, and style guides. Stay updated with industry trends , emerging technologies, and front-end innovations to continuously improve team capabilities. Participate in architectural discussions , ensuring long-term scalability and maintainability of the front-end ecosystem. Get to know DevsData We are a technology consulting company and a recruitment agency, delivering software solutions to clients from Europe and the US. We work 100% remotely, in an international team, including people from Asia, London, or San Francisco. We employ people with experience in international corporations as well as students of the best technical and business universities. Find out more: https://devsdata.com

🏢 Summary: Full-time Senior DevOps Engineer role focused on maintaining and improving cloud infrastructure for a healthcare mental health platform. The position involves managing Kubernetes environments on GCP, automating infrastructure with Terraform, and supporting CI/CD and production reliability in a distributed team. The offer includes B2B contract up to 35 EUR/h + VAT with full remote work in Poland. 🗂️ Requirements: Strong experience with Kubernetes, Strong experience with Google Cloud Platform (GCP), Strong experience with Terraform, Experience with Python, Familiarity with Atlantis, Ability to support CI/CD processes, Experience troubleshooting production environments, Good English communication skills, Availability for daily overlap with Pacific Time 📃 Skills: Kubernetes, GCP, Terraform, Python, Atlantis, CI/CD, Helm 🏢 Description: Salary range: B2B - up to 35 E/h + VAT 💰 Ciklum is looking for a Senior DevOps Engineer to join our team full-time in Poland. We are a custom product engineering company that supports both multinational organizations and scaling startups to solve their most complex business challenges. With a global team of over 4,000 highly skilled developers, consultants, analysts and product owners, we engineer technology that redefines industries and shapes the way people live. About the role: As a Senior DevOps Engineer, become a part of a cross-functional development team engineering experiences of tomorrow. The client is a healthcare platform focused on mental health services. It enables clients to schedule appointments with psychologists and psychotherapists while integrating with various US insurance providers and mental health networks. The platform offers subscription packages for mental health and ensures accessibility through multiple insurance options. Responsibilities: Maintain and improve cloud infrastructure on GCP Manage and support Kubernetes-based environments Develop infrastructure automation using Terraform Collaborate closely with a Senior Infrastructure Engineer on platform reliability and scalability Support CI/CD processes and infrastructure operations Troubleshoot production issues and ensure system stability Contribute to infrastructure best practices and technical improvements Work closely with distributed teams in an international environment Requirements: Strong experience with Kubernetes Strong experience with Google Cloud Platform / GCP Strong experience with Terraform Experience with Python, since the team supports a lot of Python work Familiarity with Atlantis as part of the core infrastructure components Helm as a nice-to-have Strong communication skills, both verbal and written, to collaborate effectively with team members and stakeholders Good command of English, both spoken and written Availability for 2 hours of overlap per day with Pacific Time, either in the Pacific morning or Pacific late afternoon / end of day, mainly for handoffs What`s in it for you? Strong community: Work alongside top professionals in a friendly, open-door environment Growth focus: Take on large-scale projects with a global impact and expand your expertise Tailored learning: Boost your skills with internal events (meetups, conferences, workshops), Udemy access, language courses, and company-paid certifications Endless opportunities: Explore diverse domains through internal mobility, finding the best fit to gain hands-on experience with cutting-edge technologies Flexibility: Enjoy flexibility – full remote working possibilities Care: We’ve got you covered with company-paid medical insurance About us: At Ciklum, we are always exploring innovations, empowering each other to achieve more, and engineering solutions that matter. With us, you’ll work with cutting-edge technologies, contribute to impactful projects, and be part of a One Team culture that values collaboration and progress. With delivery centers in Wrocław and Gdańsk, our 300+ professionals in Poland drive forward-thinking solutions for global clients. Join a community where collaboration sparks innovation—and your impact reaches millions. Explore, empower, engineer with Ciklum! Interested already? We would love to get to know you! Submit your application. We can’t wait to see you at Ciklum.

🏢 Summary: Full-time Senior .NET Engineer role focused on modernizing a legacy application through incremental migration and performance-aligned redesign. The position involves analyzing complex stored procedures, building clean data access layers, and implementing comprehensive testing strategies within a cross-functional team. The project emphasizes data synchronization, hybrid data solutions, and automation tooling. 🗂️ Requirements: Strong experience with C# and .NET for building data access layers and ORM implementations, Ability to analyze and refactor complex SQL Server stored procedures, Experience with MongoDB and NoSQL patterns, Proven experience with TDD and writing unit/integration tests, Experience with Python for scripting and migration tooling, Experience using LLM/AI tools for code analysis and documentation, Understanding of event-driven architectures with Kafka, Familiarity with enterprise architectural patterns 📃 Skills: C#, .NET, SQL, T-SQL, SQLServer, MongoDB, TDD, UnitTesting, Python, LLM, AI, Kafka, SpringBoot, ORM 🏢 Description: Salary range: B2B - 39-40 E/h + VAT 💰 Ciklum is looking for a Senior .NET Engineer to join our team full-time in Poland. We are a custom product engineering company that supports both multinational organizations and scaling startups to solve their most complex business challenges. With a global team of over 4,000 highly skilled developers, consultants, analysts and product owners, we engineer technology that redefines industries and shapes the way people live. About the role: As a Senior .NET Engineer, become a part of a cross-functional development team engineering experiences of tomorrow. Project Description: Modernizing Legacy application. Responsibilities: Analyze existing stored procedures and document business logic Design clean, testable .NET data access interfaces Write unit/integration tests prior to implementation Execute incremental migration with parallel validation Ensure performance parity with legacy procedures Requirements: C#/.NET - Strong experience building data access layers, repositories, and ORM implementations SQL Server/T-SQL - Ability to analyze and deconstruct complex stored procedures MongoDB - Experience with NoSQL patterns for potential hybrid data solutions TDD/Unit Testing - Proven track record writing comprehensive test suites before implementation Python - For scripting, automation, and migration tooling LLM/AI Tools - Experience leveraging AI for code analysis, conversion assistance, and documentation generation Kafka - Understanding of event-driven architectures for data synchronization Spring Boot - Familiarity with enterprise patterns (transferable to .NET architecture) What`s in it for you? Strong community: Work alongside top professionals in a friendly, open-door environment Growth focus: Take on large-scale projects with a global impact and expand your expertise Tailored learning: Boost your skills with internal events (meetups, conferences, workshops), Udemy access, language courses, and company-paid certifications Endless opportunities: Explore diverse domains through internal mobility, finding the best fit to gain hands-on experience with cutting-edge technologies Flexibility: Enjoy flexibility – full remote working possibilities Care: We’ve got you covered with company-paid medical insurance, mental health support, and financial & legal consultations About us: At Ciklum, we are always exploring innovations, empowering each other to achieve more, and engineering solutions that matter. With us, you’ll work with cutting-edge technologies, contribute to impactful projects, and be part of a One Team culture that values collaboration and progress. With delivery centers in Wrocław and Gdańsk, our 300+ professionals in Poland drive forward-thinking solutions for global clients. Join a community where collaboration sparks innovation—and your impact reaches millions. Want to learn more about us? Follow us on Instagram , Facebook , LinkedIn . Explore, empower, engineer with Ciklum! Interested already? We would love to get to know you! Submit your application. We can’t wait to see you at Ciklum.