Full Stack Engineer

🏢 Summary: Backend Developer role focused on building and maintaining high-availability, high-traffic Java applications within a microservices architecture handling over 1 billion messages daily. The position involves developing new features, optimizing performance, ensuring data security, and working with reactive technologies, cloud services, and NoSQL databases. The role requires close collaboration with product and architecture teams on mission-critical systems. 🗂️ Requirements: Minimum 7 years experience as Backend Developer, Minimum 3 years commercial experience with Java, Advanced knowledge of Java frameworks and libraries, Experience with asynchronous or reactive Java frameworks, Advanced knowledge of unit testing and mocking frameworks, Experience with cloud technologies, Experience with large-scale NoSQL databases, Experience with microservices architecture, Experience with Docker, Experience with Kubernetes, Experience working in Agile methodology, Higher technical education, Fluent English (written and spoken) 📃 Skills: Java, Vertx, RxJava, Akka, NoSQL, Couchbase, MongoDB, Docker, Kubernetes, Cloud, Microservices, JUnit, Mockito, Agile 🏢 Description: Rakuten Viber is one of the most popular and downloaded apps in the world. Working with us provides a unique opportunity to influence hundreds of millions of our users and to be part of the journey that makes us a super-app. Our mission is to make people’s lives easier by enabling meaningful connections, from precious moments with family and friends, through managing business relationships to pursuing their passions. We are a global team of engineers dedicated to creating the best tools to ensure safe, convenient, and fun communication for millions of users worldwide. Our culture is built on innovation, teamwork, and a commitment to excellence. We offer a unique opportunity to work with cutting-edge technologies, including microservices architecture, and influence the lives of millions of people. As a Backend Developer at Viber, you will be involved in developing and maintaining high-traffic with over 1 billion messages a day and dozens of scalable services, ensuring the fast and reliable operation of our platform. Your tasks will include developing new features, optimizing performance, ensuring data security, and solving complex technical challenges within our microservices architecture, using a combination of Java, along with non-blocking and reactive approaches, Cloud services, and NoSQL databases. Responsibilities Planning, designing, developing and maintaining Java high-availability applications that can be high-volume and low-latency. Define application objectives and functionality. Ensure application designs conform with business goals. Support continuous improvement, investigating alternatives and technologies, and presenting for architectural review. Work in a highly motivated team, closely with Product and Architects teams on large mission-critical systems. Requirements At least 7 years of experience as a Backend Developer, with at least 3 years in Java. Advanced knowledge of Java, from frameworks to libraries. Experience in Async and/or reactive Java frameworks (such as Vertx, Rxjava, Akka). Advanced knowledge of unit testing frameworks and mocking. Knowledge of cloud technologies. Experience with large scale NoSQL database (such as Couchbase, MongoDB). Experience with microservices development based on Docker and Kubernetes. Experience with Agile methodology. Striving for new knowledge and skill improvement. Fluent in written and spoken English (interviews are in English). Excellent oral and written communication skills. Higher technical education. Experience leveraging AI tools to enhance productivity or decision-making is a strong advantage. Advantages Knowledge of C++. Experience working with Open Search / Elastic search. Experience with other server-side languages such as Node.js, Go, Python. Experience working with remote teams.

🏢 Summary: Backend Infrastructure Developer role focused on designing and maintaining infrastructure software and core services that support Java microservices in a large-scale cloud environment. The position involves building internal R&D tools, improving CI/CD and automation, and collaborating with DevOps and architecture teams to enhance development processes. The role emphasizes innovation, scalability, and end-to-end ownership from design to release. 🗂️ Requirements: 5+ years Backend Development experience, Minimum 3 years commercial Java experience, Hands-on experience with CI/CD, Experience with automation and tooling, Experience with cloud infrastructure, Proficiency in cloud environments, Experience with microservices architecture, End-to-end project ownership experience, English proficiency 📃 Skills: Java, CI/CD, Automation, Cloud, Microservices, AWS, Kubernetes, Helm, ArgoCD, Go, Python, Node.js, Vert.x, RxJava, Spring, WebFlux 🏢 Description: Rakuten Viber is one of the most popular and downloaded apps in the world. Working with us provides a unique opportunity to influence hundreds of millions of our users and to be part of the journey that makes us a super-app. Our mission is to make people’s lives easier by enabling meaningful connections, from precious moments with family and friends, through managing business relationships to pursuing their passions. At Viber’s Backend Infra team, we provide vital infrastructure solutions that support the development of Java microservices. We enable other teams to focus on feature development by providing an internal R&D ecosystem, including libraries, plugins, testing solutions, and more. We are also responsible for core services that multiple teams use across Viber. We’re a collaborative, agile team that thrives on innovation and continuous improvement. Responsibilities Design, develop, and maintain infrastructure software solutions and core services. Explore and implement new technologies to improve infrastructure. Collaborate closely with DevOps and architect teams. Partner with product teams to provide infrastructure solutions that support feature development. Bring innovative ideas and proactive initiatives to improve infrastructure and development processes. Requirements 5+ years of experience as a Backend Developer, with at least 3 years in Java. Hands-on experience in infrastructure-related areas such as CI/CD, automation, tooling, and cloud infrastructure. Proficient in working within a cloud environment. Strong ability to manage projects end-to-end, from design to release. Experience with microservices development and architecture. Excellent communication skills in English. Advantages Previous experience working in infrastructure teams. Familiarity with other backend languages (such as Go, Python, Node.js). Advanced knowledge of AWS services. Familiarity with the Kubernetes ecosystem (such as Helm, ArgoCD). Experience with reactive programming frameworks (such as Vert.x, RxJava, Spring WebFlux).

🏢 Summary: The role involves developing and enhancing the Viber Android client, focusing on building high-quality, scalable features for a global communication app. The position requires close collaboration with cross-functional teams to deliver efficient, user-centered solutions. It offers technically challenging tasks within a large-scale Android environment. 🗂️ Requirements: 5+ years of commercial Android development experience, Strong proficiency in Java and Kotlin, Experience with Android Jetpack components, Knowledge of Collections and Concurrency/Multithreading in Java, Experience with Coroutines and Flow, Proficiency with Dagger 2 and Gradle, Experience in multi-module Android projects, Experience with SQL databases and Room, Ability to write unit tests, Proficiency with Git, Experience with MVP, MVI, or MVVM architecture, Understanding of design patterns and application architecture, Intermediate spoken English 📃 Skills: Android, Java, Kotlin, Jetpack, WorkManager, Paging, ViewBinding, LiveData, Coroutines, Flow, Dagger, Gradle, SQL, Room, Git, MVP, MVI, MVVM, Collections, Concurrency 🏢 Description: Rakuten Viber is one of the most popular and downloaded apps in the world. Working with us provides a unique opportunity to influence hundreds of millions of our users and to be part of the journey that makes us a super-app. Our mission is to make people’s lives easier by enabling meaningful connections, from precious moments with family and friends, through managing business relationships to pursuing their passions. We are a global team of engineers dedicated to creating the best tools to ensure safe, convenient communication for millions of users worldwide. Our culture is built on innovation, teamwork, and a commitment to excellence. We’re looking for an experienced, highly motivated Android developer to join our team. As an Android Developer, you will be responsible for design and development of Viber Android client. We offer many interesting and challenging tasks that will allow you to extend your technical abilities delivering the product of the highest quality to our users. Responsibilities Participate in the development of the Viber client for Android, contributing to the enhancement and maintenance of existing features Collaborate with a diverse team of developers to efficiently produce new features, complete proposed initiatives, and contribute to overall application improvements Quickly grasp clients’ requirements, technology needs, and solution architecture to deliver high-quality solutions Work closely with product managers, the design team, and others to develop appropriate solutions that align with user experience and design guidelines. Requirements 5+ years of commercial experience in Android application development Strong proficiency in Java, Kotlin, and/or Android development Solid understanding of Collections, Concurrency/Multithreading in Java, Coroutines/Flow, and experience with Android Jetpack components (WorkManager, Paging, ViewBinding, LiveData) Proficient in Dagger 2, multi-module projects, and Gradle for building and maintaining Android applications Thorough understanding of mobile application design principles and UX Experience with databases, including SQL, optimization and Room Proficiency in writing unit tests and version control using Git Familiarity with design patterns (GoF), architecture, and refactoring of applications Experience in MVP/MVI/MVVM architecture-based development Intermediate spoken level of English for effective communication within the team. Experience leveraging AI tools to enhance productivity or decision-making is a strong advantage.

🏢 Summary: Role focused on designing and developing new features for a large-scale iOS application, ensuring high performance, code quality, and reliability. The position involves optimizing, refactoring, and maintaining the iOS client while delivering high-quality user experiences. 🗂️ Requirements: 5+ years of production mobile software development experience, Proficiency in Objective-C, Proficiency in Swift, Strong experience in iOS development, Strong knowledge of Object-Oriented Programming, Strong knowledge of algorithms, Strong knowledge of design patterns, Experience with multithreading, Experience with unit testing 📃 Skills: Objective-C, Swift, iOS, OOP, Algorithms, Design-patterns, Multithreading, Unit-testing, Mobile 🏢 Description: Rakuten Viber is one of the most popular and downloaded apps in the world. Working with us provides a unique opportunity to influence hundreds of millions of our users and to be part of the journey that makes us a super-app. Our mission is to make people’s lives easier by enabling meaningful connections, from precious moments with family and friends, through managing business relationships to pursuing their passions. As an iOS Developer, you will be responsible for design and development of Viber iOS client. We offer many interesting and challenging tasks that will allow you to extend your technical abilities delivering the product of the highest quality to our users. The ideal candidate is interested in improving our users’ experience and wants to make a positive impact on the team. Responsibilities Development of new features of Viber app. Improve code quality through writing unit tests and performing code reviews. Improve quality of application and bug fixing. Applications optimization and Code refactoring. Requirements At least 5 years of production mobile software development experience. Proficient in Objective-C/ Swift and iOS development. Experience collaborating with multiple cross-functional teams including support, product management, developers. Expert in Object-Oriented programming, algorithms, design patterns, multi-threading. Experience in Unit Testing. Strong communication skills. Intermediate spoken level of English. Availability to work full-time job in a hybrid mode (3 times a week at the office). Experience leveraging AI tools to enhance productivity or decision-making is a strong advantage.

🏢 Summary: QA Team Lead role combining hands-on manual and automation testing with leading a small agile QA team, ensuring high-quality delivery of mobile, desktop, and backend microservices products. The position focuses on defining QA strategy, executing comprehensive test plans, and expanding test automation frameworks across complex multi-component architectures. 🗂️ Requirements: 3+ years experience as QA Team Lead (manual and automation), 6+ years experience in mobile application testing (Web, Desktop, Native iOS, Native Android), 6+ years experience in backend microservices testing, Proficiency with test automation tools and frameworks, Experience with Jira, TestRail and GitLab CI, Experience developing and implementing QA strategies, Strong knowledge of Agile methodologies, Ability to work with complex multi-component architectures, Fluent English 📃 Skills: QA, Automation, Testing, Mobile, iOS, Android, Web, Desktop, Microservices, Jira, TestRail, GitLab, CI, Agile 🏢 Description: Rakuten Viber is one of the most popular and downloaded apps in the world. Working with us provides a unique opportunity to influence hundreds of millions of our users and to be part of the journey that makes us a super-app. Our mission is to make people’s lives easier by enabling meaningful connections, from precious moments with family and friends, through managing business relationships to pursuing their passions. We are a global team of engineers dedicated to creating the best tools to ensure safe, convenient communication for millions of users worldwide. Our culture is built on innovation, teamwork, and a commitment to excellence. We’re looking for an experienced, highly motivated QA Team Lead to join our team and lead a group of skilled QA engineers. Responsibilities Lead, mentor, and manage an agile team of ~4 QA engineers, including hiring, training, and mentoring, alongside hands-on testing (minimum ~50%) Collaborate with cross-functional agile squads, providing QA expertise and guidance throughout the development lifecycle Develop and execute comprehensive QA strategies to ensure the delivery of high-quality products such as server side services and mobile and desktop applications Oversee the creation of test plans, test cases, and test scripts, ensuring comprehensive coverage of functional and non-functional requirements Execute test cases, conduct thorough regression testing, and analyze results to identify and address defects Collaborate effectively with leadership, product managers, developers, and other stakeholders to understand requirements and provide feedback on design and functionality Drive the implementation and expansion of test automation frameworks to enhance testing efficiency and coverage Requirements At least 3 years of experience as a manual and automation QA Team Lead At least 6 years of experience in mobile application testing , including Web, Desktop, Native iOS and Native Android platforms At least 6 years of experience in backend micro services testing . Proficiency in test automation tools and frameworks (Jira, TestRail, AI tools, gitlab CI) Proven ability to develop and implement comprehensive QA strategies aligned with project goals and timelines Strong understanding of Agile methodologies and experience working in cross-functional squads Proficiency in understanding and navigating complex multi-component solution architectures Excellent leadership and communication skills Fluent in written and spoken English Advantages Bachelor’s degree in Computer Science, Engineering, or related field Experience with instant messaging applications and/or Ad Tech Solutions Experience working with remote teams

🏢 Summary: Offer for an experienced C++/Qt Developer to build and enhance a cross-platform desktop communication application for Windows, macOS, and Linux. The role focuses on developing new features, optimizing performance, and maintaining high-quality architecture across the full application stack. It involves deep work with UI, networking, and database layers in a large-scale production environment. 🗂️ Requirements: Minimum 5 years of professional C++/Qt development experience, Expert-level proficiency in Qt framework, including Qt Quick and QML, Strong expertise in modern C++ standards (C++17/20), Experience with CMake build system, Experience with Python and JavaScript, Proven cross-platform development for Windows, macOS, Linux, Extensive experience with SQLite or relational databases, Strong knowledge of client-server architecture and network programming, Experience with multithreading and concurrency control, Strong memory management skills, Experience with performance profiling and optimization tools 📃 Skills: C++, Qt, QML, QtQuick, CMake, Python, JavaScript, SQLite, Windows, macOS, Linux, Multithreading, Concurrency, Networking, Profiling 🏢 Description: Rakuten Viber is one of the most popular and downloaded apps in the world. Working with us provides a unique opportunity to influence hundreds of millions of our users and to be part of the journey that makes us a super-app. Our mission is to make people’s lives easier by enabling meaningful connections, from precious moments with family and friends, through managing business relationships to pursuing their passions. We are building and enhancing Viber for Desktop, the vital cross-platform extension of the Viber ecosystem. Our application empowers users across Windows, macOS, and Linux to enjoy seamless, high-quality free voice and video calls, exchange instant and group messages, and securely transmit multimedia content directly from their desktop environments. We are seeking an experienced, highly motivated, and self-directed C++/Qt Developer with a strong technical background and a proactive, entrepreneurial approach to join our engineering team. Responsibilities Feature Development: Drive the end-to-end development of new features and communication capabilities within the cross-platform Viber for Desktop application, utilizing C++ and the Qt framework (QML/Qt Quick). Optimization & Debugging: Perform deep-level diagnosis, debugging, and performance optimization across the entire application stack, from the UI (Qt Quick/QML) down to network layers and database interactions (SQLite). Code Quality & Architecture: Actively participate in architecture discussions and contribute to the ongoing refinement, refactoring, and standardization of the C++ codebase to maintain high quality and minimize technical debt. Collaboration & Deployment: Collaborate closely with product, design, and QA teams to ensure seamless integration and deployment of new functionalities across Windows, macOS, and Linux platforms. Requirements Experience: Minimum of 5 years of professional experience in C++/Qt development. Qt Framework: Expert-level proficiency with the Qt framework, including Qt Quick and QML. C++ Standards: Demonstrated expertise in modern C++ standards (C++17/20). Tooling & Scripting: Solid experience with the CMake build system, Python, and JavaScript (JS). Cross-Platform: Proven track record in developing and maintaining cross-platform applications targeting Windows, macOS, and Linux operating systems. Database: Extensive experience working with relational databases, specifically SQLite. Networking: Deep understanding and practical experience with client-server architecture and network programming concepts. Concurrency & Memory: Comprehensive knowledge of multi-threading, concurrency control, and robust memory management techniques. Performance: Proficiency in utilizing performance profiling and optimization tools.

🏢 Summary: Software Engineer role focused on building and scaling a multi-tenant customer engagement platform for enterprise contact centers. The position involves developing backend services, real-time communication components, and cloud-native infrastructure using Ruby on Rails, Node.js, and Kubernetes on Azure. You will work on distributed systems, integrations, and CI/CD pipelines to ensure reliability, scalability, and security. 🗂️ Requirements: Strong experience with Ruby on Rails 7.x and Ruby 3.x, Experience with Node.js and Express.js, Hands-on experience with PostgreSQL schema design and query optimization, Experience designing and maintaining REST APIs, Experience with authentication and authorization mechanisms (JWT, OAuth2, OIDC, policy patterns), Experience with background job systems, Experience with Redis (caching, pub/sub), Experience with Docker and writing Dockerfiles, Understanding of Kubernetes and Helm, Experience with CI/CD pipelines, Experience integrating third-party REST/webhook APIs 📃 Skills: Ruby, Rails, PostgreSQL, Redis, Node.js, Express, WebSockets, Docker, Kubernetes, Azure, AKS, Helm, GitLab, CI/CD, RSpec, Jest, JWT, OAuth2, OIDC, Pundit, Devise, DelayedJob, ActiveJob, Sidekiq, JSON:API, Graphiti, Prometheus, NewRelic, SonarCloud, Aikido, Genesys, Vonage, WebRTC, SIP, Terraform, Cloudflare, React 🏢 Description: About Us VC-backed, 15-person team across Poland, Mexico & the Philippines - with global expansion underway. We’re defining a new category: a customer contact & collaboration layer on top of enterprise contact center and CRM platforms - already trusted by global enterprises across Europe, Asia, and the Americas. Our platform is used by enterprise clients across multiple industries, with a strong focus on reliability, scalability, security, and seamless real-time communication experiences. We combine modern cloud-native architecture with deep expertise in WebRTC, contact center integrations, and customer engagement technologies. As a rapidly growing company, we maintain a strong engineering culture built around ownership, collaboration, continuous improvement, and pragmatic problem-solving. We value people who are curious, proactive, and excited about building meaningful products in a fast-moving environment. About the Role We’re looking for a Software Engineer with strong technical skills and hands-on experience building modern distributed systems and web applications. In this role, you’ll help design, develop, maintain, and improve a multi-tenant customer engagement platform used primarily by enterprise contact centers. You’ll work across backend services, infrastructure, and internal tooling to ensure our systems remain scalable, reliable, secure, and easy to evolve. Our platform combines multiple technologies and real-time communication channels, including voice, video, chat, callbacks and many more, integrated with providers such as Genesys Cloud and Vonage. The backend architecture includes: A Ruby on Rails API responsible for core business logic, authentication, integrations, and account management Several Node.js services handling real-time signaling, visitor data processing, and analytics Cloud-native infrastructure running on Kubernetes and Azure services You’ll work closely within a small, highly collaborative engineering team where ownership and initiative are highly valued. We’re looking for someone who enjoys solving complex technical challenges, moving quickly, contributing ideas, and building high-quality software that delivers real value to customers. Responsibilities Develop and maintain the core REST/JSON:API backend in Ruby on Rails 7 (PostgreSQL, Redis, Puma, Delayed Job) + upgrade to RoR 8 Own the Node.js signalling server built on Express + WebSockets Extend and debug integrations with Genesys Cloud and Vonage Write and maintain authorization policies and multi-tenant access control logic Design and run database migrations on a mature PostgreSQL schema (200+ migrations) Work within a Kubernetes on Azure AKS environment - understand Helm charts, environment configs, and deployment pipelines Participate in GitLab CI/CD - security checks (SonarCloud, Aikido.dev), Docker builds, staged deploys Gradually improve test coverage using RSpec (Rails) and Jest (Node.js) Required Skills Ruby on Rails Rails 7.x, Ruby 3.x (-> 8.x, 4.x) PostgreSQL - schema design, migrations, query optimization REST API design; experience with JSON:API / Graphiti is a plus Background jobs: Delayed Job, ActiveJob, or Sidekiq Authentication: Devise, JWT, OAuth2, OIDC Authorization: Pundit or similar policy pattern Node.js Node.js 24+, Express.js WebSockets Redis (caching, pub/sub, locking patterns) Azure Storage (Tables, Queues) or equivalent cloud storage SDKs Comfort with async code General Backend Designing and consuming third-party REST/webhook APIs Docker - writing and maintaining Dockerfiles Kubernetes basics - reading Helm charts, understanding namespaces and config maps Git + CI/CD pipelines Structured logging and APM tools (New Relic, Prometheus) Nice to Have Experience with Genesys Cloud or other contact center solution Experience with Vonage or other CPaaS telephony (SIP, WebRTC) Terraform / Azure infrastructure Cloudflare Workers React (the frontend teams will occasionally need backend pairing) Compensation 19-24k B2B Meaningful ESOP upside (VC-backed) 26 days of paid holiday

🏢 Summary: The role involves developing and enhancing a language proficiency testing platform as part of an agile team, focusing on scalable backend and cross-platform frontend solutions. The position requires strong experience in microservices, serverless architecture, CI/CD, and cloud-based systems, along with active participation in code reviews and technical decision-making. You will work on improving code quality, testing practices, and system reliability in a remote or hybrid model. 🗂️ Requirements: 7+ years of software development experience, Fluency in English, Experience with microservices architecture, Experience with serverless architecture, Experience with CI/CD pipelines, Strong knowledge of unit, integration, and E2E testing, Strong knowledge of Java and related frameworks, Experience with relational databases and MongoDB, Experience with messaging systems (AWS SQS required), Strong knowledge of JUnit, Knowledge of backend security best practices and OWASP, Experience with AWS cloud services, Experience with Docker, Experience with cross-platform frontend development, Experience with Angular and React ecosystems 📃 Skills: Java, Play, Spring, SBT, Maven, Gradle, MongoDB, SQL, SQS, RabbitMQ, Kafka, JUnit, OWASP, AWS, Docker, Selenium, Sonar, Angular, TypeScript, React, Redux, MUI, Electron, Axios, Jest, Vitest, Karma, Jasmine 🏢 Description: Full Stack Developer will involve developing and enhancing a platform designed for conducting language proficiency tests. Your responsibilities: Work on an agile engineering team, following Agile best practices while writing maintainable and scalable code and influencing team decisions Collaborate with stakeholders to design and test new product functionalities Review the code of other team members and provide constructive direction. Promote a culture of sharing through mentoring and knowledge exchange Drive continuous improvement of code quality, customer experience, and maintainability of products/features Independently clarify technical requirements, assess development estimates, and apply a broad range of design approaches We are looking for you, if you have: 7+ years of experience Fluency in English is a must Experience on Microservice and Serverless architecture Experience on CI/CD practices Solid testing knowledge – E2E, unit testing, integration testing, etc. Technicall skills: Java: Play3 Framework/Spring Boot SBT, Maven, Gradle MongoDB and Relational Databases Bus messaging systems. AWS SQS is a must, but other technologies like RabbitMQ and Kafka will also be considered Strong Junit knowledge Backend security best practices, including familiarity with OWASP Experience with AWS technologies, Docker, Selenium, Sonar Cross-platform development Angular 13 + TypeScript React + Redux + Material UI (MUI) + TypeScript Electron Axios Jest, Vitest, Karma and Jasmine We offer: Participation in interesting and demanding projects Flexible working hours A great, non-corporate atmosphere Stable employment conditions (contract of employment or B2B contract) Opportunities for development and promotion Attractive package of benefits Work model: remote or hybrid (2 days per week from the office) We reserve the right to contact the selected candidates.

🏢 Summary: Senior React Native Developer role focused on building and evolving a large-scale, multi-module mobile platform used by millions of users across Europe and North America. The position involves driving architectural decisions, developing complex mobile applications in React Native and TypeScript, and mentoring engineers while ensuring high performance and scalability. You will collaborate cross-functionally and contribute to CI/CD, native integrations, and continuous technical improvements. 🗂️ Requirements: 5+ years commercial software development experience, 4+ years experience with React Native, Experience building and maintaining large-scale mobile applications, Strong knowledge of TypeScript and modern JavaScript, Experience with React Hooks, Understanding of modular and multi-module architecture, Experience with MobX, Experience with React Query (TanStack Query), Knowledge of native mobile development concepts for iOS and Android, Experience integrating REST APIs, Experience with GraphQL, Experience with form management solutions, English proficiency at B2 level or higher, Polish proficiency at B2 level or higher, Residence in Poland 📃 Skills: React, ReactNative, TypeScript, JavaScript, MobX, ReactQuery, TanStackQuery, iOS, Android, REST, GraphQL, CI/CD, Firebase 🏢 Description: Join one of Europe's largest mobile platforms, delivering digital services used by millions of users across multiple countries in Europe and North America. Built on a multi-module architecture, the platform enables rapid product development, high code reusability, and continuous expansion into new business areas. As a Senior React Native Developer, you will play a key role in shaping the architecture of a big mobile ecosystem, driving technical decisions, mentoring other engineers, and delivering high-quality solutions at scale. Your tasks Design, develop, and maintain complex mobile applications using React Native and TypeScript Drive architectural decisions and contribute to the evolution of our multi-module platform Lead technical discussions and participate in solution design Review code, mentor team members, and promote engineering best practices Collaborate closely with Product Owners, UX Designers, Backend Engineers, QA Engineers, and Architects Improve application performance, reliability, scalability, and maintainability Contribute to CI/CD processes and development tooling Support the integration of native mobile capabilities and third-party services Identify technical debt and proactively drive improvements across the codebase Requirements At least 5 years of commercial software development experience, including at least 4 years with React Native Proven track record of building and maintaining large-scale mobile applications Strong expertise in TypeScript, modern JavaScript, and React Hooks Solid understanding of modular and multi-module application architecture Hands-on experience with MobX and React Query (TanStack Query) Knowledge of native mobile development concepts and creating native modules for iOS and Android Practical experience with REST APIs, GraphQL, and form management solutions English and Polish proficiency at the B2 level or higher Residing in Poland required Nice-to-have requirements Payment integrations and mobile wallet solutions Geolocation and location-based services Firebase services and analytics Mobile security best practices Observability and monitoring tools Background in large-scale international products Agile delivery experience (Scrum/Kanban) What we offer Great Place to Work since 2015 - it’s thanks to feedback from our workers that we get this special title and constantly implement new ideas Employment stability - revenue of PLN 2.1BN, no debts, since 2006 on the market We share the profit with Workers - over PLN 76M has already been allocated for this aim since 2022 Attractive benefits package - private healthcare, benefits cafeteria platform, car discounts and more Comfortable workplace – class A offices or remote work Dozens of fascinating projects for prestigious brands from all over the world PLN 1 000 000 per year for your ideas - with this amount, we support the passions and voluntary actions of our workers Investment in your growth – meetups, webinars, training platform and technology blog – you choose Fantastic atmosphere created by all Sii Power People If you want to work on systems with high operational significance — apply now!

🏢 Summary: Remote Senior Backend Node.js Developer role focused on building and scaling an event-driven microservices trading platform. The position involves end-to-end development, collaborating across product, QA, and DevOps to deliver high-performance, scalable trading solutions. B2B contract with overlap required with NYC working hours. 🗂️ Requirements: Bachelor’s Degree in Computer Science or related field, 3-5 years professional web application development experience, Expert-level Node.js knowledge, Expert-level TypeScript knowledge, Experience with distributed systems, Experience with Apache Kafka, Redis, Kubernetes, MongoDB, Experience with automated unit testing and TDD, Strong understanding of performance optimization and computational complexity, Knowledge of algorithms and design patterns, Fluent English (written and spoken) 📃 Skills: Node.js, TypeScript, Kafka, Redis, Kubernetes, MongoDB, Microservices, TDD, Algorithms, DesignPatterns, Web, DistributedSystems 🏢 Description: We are looking for a performance-driven backend Senior Node.js Developer who can help us bring our client's trading solutions to the next level of functionality, scalability, and user experience. They are actively developing a new event-driven microservices architecture to form a foundational platform for delivering new trading applications. You will be responsible for delivering software end-to-end , from liaising with product managers and designers, to coordinating across international development teams on engineering and architecture to working with QA and DevOps teams - all ultimately to deliver a quality, innovative product to the traders and investors who depend on the platform every day. Requirements: Fluent English language [both written and spoken] Education: at least Bachelor's Degree, preferably in Computer Science 3-5 years' professional web application development experience Expert-level Node.js and TypeScript knowledge, and curiosity to learn more Broad knowledge of web platform and technologies Superior analytical and problem-solving ability Effective communication skills to work with different teams across an international company Experience with modern distributed systems and infrastructure technologies, including Apache Kafka, Redis, Kubernetes, and MongoDB Automated unit testing and test-driven development Robust understanding of performance issues, computational complexity, and code optimization. Familiarity and implementation of industry-standard algorithms and design patterns Proactive and team player who can deliver in a high-pressure demanding environment Nest.js – nice to have Offer details: 100% remote job preferrably at least 4-5 hours overlap with NYC working hours B2B contract rate up to 50 USD/h net Don't hesitate and apply now!