.NET Backend Developer

🏢 Summary: Senior Backend Developer role focused on Risks & Inspections and Safety Intelligence projects using .NET/C# and event-driven architecture. The position involves API and service development, domain modeling, integrations, and advanced testing practices in a hybrid work model based in Warsaw. The contract is full-time B2B for 12 months with possible extension and requires English proficiency. 🗂️ Requirements: Strong proficiency in .NET, Strong proficiency in C#, Experience in API development, Experience in service implementation, Familiarity with event-driven architecture, Expertise in domain modeling, Knowledge of tenant-aware data management, Experience with unit testing, Experience with integration testing, Experience with service testing, Experience with contract testing, English proficiency, Availability for hybrid work in Warsaw 📃 Skills: .NET, C#, API, React, MDM, Testing, Architecture, Queues, Idempotency, Integration, Authorization 🏢 Description: Work model: hybrid - 2 days a week, Warsaw office. Project language: English. Start: ASAP or 30 days. Remuneration: B2B > up to 42 EUR. FTE: full-time (40 hours per week) Business Travel: may travel once a year to France or the Netherlands. Equipment: laptop provided by the client Industry: Information Services. Recruitment process - 1 technical and soft skills meeting for 1-1.5 hours. We are seeking a skilled Backend Developer to join our innovative team focusing on Risks & Inspections and Safety Intelligence projects. The ideal candidate will possess robust experience in .NET / C# development, API and service implementation, and event-driven design patterns. You will play a critical role in ensuring effective domain modeling, integration with various services, and thorough testing methodologies. Main Responsibilities: Implementing strong .NET / C# development practices. Executing API and service implementations. Utilizing event-driven patterns such as events, queues, and idempotency. Developing comprehensive domain models and state management. Managing tenant-aware data access and conducting authorization checks. Integrating with MDM, workflow, audit, and various data services. Conducting unit, integration, service, and contract testing. Collaborating on specifications from structured requirements. Key Requirements: Strong proficiency in .NET / C#. Experience in API and service development. Familiarity with event-driven software architecture. Expertise in domain modeling and traceability. Knowledge of tenant-aware data management. Experience in effective testing methodologies across multiple domains. Nice to Have: Experience with React or similar frameworks. Understanding of spec-driven development practices. Capability to work in a contract-first delivery environment. Experience with cross-capability collaboration. Other Details: The role is designed for a new initiative with a senior-level requirement. Two 5-person teams are being built with a target start date within 3-4 weeks. The initial contract duration is 12 months, with potential extensions subject to a one-month notice period. The work is primarily remote, requiring office attendance two days a week. Candidates may need to travel to the Netherlands or France once during the year. English language proficiency is necessary, and equipment will be provided by the organization.

🏢 Summary: Senior .NET Backend Engineer role focused on building modern API and event-driven integrations for research systems in the pharmaceutical industry. The position involves replacing legacy APIs, implementing cloud-based integration solutions, and supporting event-driven architecture initiatives in a remote or hybrid B2B setup. Long-term contract with English-speaking environment and collaboration with technical and business stakeholders. 🗂️ Requirements: Strong experience with .NET, Experience with ASP.NET Core, Experience building enterprise integration APIs, Knowledge of Azure or AWS, Experience with Infrastructure as Code, Hands-on experience with Entity Framework, Experience with unit testing, Knowledge of software quality practices, Strong analytical and problem-solving skills, Ability to work independently, Excellent communication skills, Confidence working with stakeholders 📃 Skills: .NET, ASP.NET, Azure, AWS, Bicep, EntityFramework, Kafka, Redis, Docker, CI/CD, GitHub, APIs 🏢 Description: 🌍Work mode - fully remote or hybrid - 2 days from the office in Warsaw. 📑 Assignment type : B2B ⏳Contract length >10-12 months + extensions. ⏰Start - ASAP/1 month. 📕Language - English. ⚙️Industry - pharmaceutical. 💼 Recruitment process - 2 interviews with the client. 💻 Workload : Full time. Summary: The Senior .Net Backend Engineer role is focused on building innovative integrations for research systems. The primary objective is to modernize data exchange mechanisms to enhance scientific work and accelerate innovation in research. Main Responsibilities: Build API and event-based integrations between existing and new research systems. Replace current legacy APIs with a new modern greenfield API surface. Assist feature teams with identifying and implementing event-driven architecture. Key Requirements: Strong experience developing backend applications using .NET / ASP.NET Core. Experience building enterprise integration APIs. Knowledge of cloud platforms such as Azure and/or AWS. Experience with Infrastructure as Code (e.g., Bicep). Hands-on experience with Entity Framework. Experience with unit testing and modern software quality practices. Strong analytical and problem-solving skills. Ability to work independently with a high degree of ownership and accountability. Excellent communication skills and confidence working directly with stakeholders. Nice to Have: Experience with Kafka. Knowledge of Electronic Laboratory Notebooks (ELN). Familiarity with Redis. Experience with Docker / Container Apps. Knowledge of CI/CD practices, GitHub Actions. Other Details: Team Context: Works closely with technical and business stakeholders in a collaborative environment.

🏢 Summary: Senior .NET Backend Engineer role focused on building modern API and event-driven integrations for research systems in the pharmaceutical industry. The position involves replacing legacy APIs, supporting event-driven architecture, and working with cloud-based enterprise integrations in a remote or hybrid B2B setup. Long-term full-time contract with English-speaking international collaboration. 🗂️ Requirements: Strong experience with .NET, Experience with ASP.NET Core, Experience building enterprise integration APIs, Knowledge of Azure or AWS, Experience with Infrastructure as Code, Hands-on experience with Entity Framework, Experience with unit testing, Knowledge of modern software quality practices, Strong analytical and problem-solving skills, Ability to work independently, Excellent communication skills, Confidence working with stakeholders 📃 Skills: .NET, ASP.NET, Azure, AWS, Bicep, EntityFramework, Kafka, Redis, Docker, CI/CD, GitHub, API 🏢 Description: 🌍Work mode - fully remote or hybrid - 2 days from the office in Warsaw. 📑 Assignment type : B2B ⏳Contract length >10-12 months + extensions. ⏰Start - ASAP/1 month. 📕Language - English. ⚙️Industry - pharmaceutical. 💼 Recruitment process - 2 interviews with the client. 💻 Workload : Full time. Summary: The Senior .Net Backend Engineer role is focused on building innovative integrations for research systems. The primary objective is to modernize data exchange mechanisms to enhance scientific work and accelerate innovation in research. Main Responsibilities: Build API and event-based integrations between existing and new research systems. Replace current legacy APIs with a new modern greenfield API surface. Assist feature teams with identifying and implementing event-driven architecture. Key Requirements: Strong experience developing backend applications using .NET / ASP.NET Core. Experience building enterprise integration APIs. Knowledge of cloud platforms such as Azure and/or AWS. Experience with Infrastructure as Code (e.g., Bicep). Hands-on experience with Entity Framework. Experience with unit testing and modern software quality practices. Strong analytical and problem-solving skills. Ability to work independently with a high degree of ownership and accountability. Excellent communication skills and confidence working directly with stakeholders. Nice to Have: Experience with Kafka. Knowledge of Electronic Laboratory Notebooks (ELN). Familiarity with Redis. Experience with Docker / Container Apps. Knowledge of CI/CD practices, GitHub Actions. Other Details: Team Context: Works closely with technical and business stakeholders in a collaborative environment.

🏢 Summary: Fullstack Developer role focused on building and evolving Java-based microservices and modern Angular Single Page Applications within an event-driven architecture. The position emphasizes backend development with Spring Boot, Kafka integration, and secure, scalable solutions, while contributing to CI/CD pipelines and frontend best practices. Work involves close collaboration on solution design, security implementation, and continuous improvement in an Agile environment. 🗂️ Requirements: Strong hands-on experience with Java 17–21, Strong experience with Spring Boot 3.x, Experience with microservices architecture, Experience with Kafka in event-driven or messaging systems, Strong practical experience with SQL and Oracle, Experience or strong understanding of Redis, Experience with Domain Driven Design, Experience with Node.js, Experience with TypeScript, Experience building Single Page Applications with Angular, Strong knowledge of Angular architecture and best practices, Strong understanding of web application security, Practical knowledge of OIDC and OAuth2, Experience with Git, Experience working in Agile methodologies 📃 Skills: Java, Spring, SpringBoot, Microservices, Kafka, SQL, Oracle, Redis, DDD, Node.js, TypeScript, Angular, SPA, Security, OIDC, OAuth2, Git, Agile 🏢 Description: Location: Hybrid work model – 2-3 days per week from the Warsaw office Salary: 160 – 170 PLN net/h (B2B via Experis) Tasks: •    Design, develop, and maintain fullstack applications with a strong emphasis on backend and modern frontend architectures •    Build high-quality, maintainable, secure, scalable, and testable software aligned with business requirements •    Develop and evolve Java-based microservices using Spring Boot •    Contribute to Single Page Applications development ensuring frontend best practices •    Collaborate with business and technical stakeholders to clarify and refine functional and non-functional requirements •    Participate in solution design pre-project studies and technical decision-making •    Integrate systems using event-driven architectures and streaming platforms •    Optimize and maintain existing codebases •    Implement execute and maintain automated tests and CI/CD pipelines •    Ensure application security including identity management and secure authentication flows •    Maintain and update technical documentation •    Participate in internal and external developer communities to share best practices •    Continuously improve skills in modern technologies and software engineering practices Requirements: Backend & Architecture •    Strong hands-on experience with Java 17–21 focusing on modern Java •    Strong experience with Spring Boot 3.x and microservices architectures •    Required experience with Kafka in event-driven or messaging-based systems •    Strong practical experience with SQL using Oracle •    Experience or strong understanding of Redis •    Experience with Domain Driven Design Frontend •    Required experience with Node.js •    Required experience with TypeScript •    Solid experience building Single Page Applications using Angular •    Strong knowledge of Angular best practices architecture and maintainability •    Experience with SPA development •    Webpack knowledge is a nice to have Security •    Strong understanding of web application security •    Practical knowledge of OIDC and OAuth2 protocols •    Experience with identity management platforms as a strong advantage •    Awareness of OWASP principles certifications are a plus DevOps & Tooling •    Required experience with Git •    Experience with CI/CD pipelines GitLab CI and Jenkins as a nice to have •    Maven knowledge as a nice to have •    Docker and Kubernetes knowledge as a nice to have •    Experience with IntelliJ and VS Code •    Knowledge of Jira and Confluence •    Python knowledge as a nice to have •    Practice with AI based code generation tools as a nice to have Methodologies & Ways of Working •    Experience working in Agile methodologies such as Scrum and Kanban •    DevOps mindset and practices •    Ability to collaborate in distributed international teams Offer: •    Multisport card •    Private healthcare •    Access to an e‑learning platform •    Group life insurance

🏢 Summary: Backend Developer role focused on designing and building scalable, secure microservices and APIs using Java and Spring Boot in a cloud-oriented environment. The position emphasizes strong data modeling, architecture design, and CI/CD-driven delivery within Agile teams. The contractor will develop resilient backend solutions and ensure high code quality and reliability. 🗂️ Requirements: Hands-on experience with API and Microservices development in Java or Spring Boot, Proficiency in Java/J2EE application development, Experience with Spring Framework and Hibernate JPA, Experience building and consuming REST web services, Experience working with XML and JSON, Experience with relational or NoSQL databases (Oracle, PostgreSQL, MongoDB), Experience with CI/CD pipelines and Jenkins, Experience with Docker and Git, Unix proficiency, Experience working in Agile methodologies (Scrum or Kanban) 📃 Skills: Java, Spring, SpringBoot, J2EE, Hibernate, JPA, REST, XML, JSON, Oracle, PostgreSQL, MongoDB, Jenkins, Docker, Git, Unix, CICD, Microservices, Agile, Scrum, Kanban 🏢 Description: Location : Cracow Mode : Hybrid (6 days per month at the office - flexible) Contract : B2B Rate : 160-170 PLN/h Introduction & Summary We are seeking a skilled Backend Developer who possesses a deep knowledge of data modeling and architecture. The ideal candidate should have extensive experience in API development using core Java and Spring Boot, with a strong grasp of security principles and Agile methodologies. The role requires an analytical mindset, capable of designing resilient and scalable solutions while working cross-functionally to foster collaboration and innovation. Main Responsibilities Ensure proper definition and architecture of non-functional requirements in design. Develop and grow skills in designing cloud-based, secure, and adaptable solutions. Build scalable, highly reliable product features through effective software design and implementation. Apply problem-solving and analytical skills to diverse challenges. Interact with cross-functional teams for scalable solution production. Estimate engineering efforts and develop realistic schedules. Identify and resolve complex production issues efficiently. Conduct comprehensive design and code reviews and perform unit testing. Utilize source control and bug tracking systems responsibly. Key Requirements Hands-on experience in API and Microservices development using core Java and/or Spring Boot . Proficient in application development using Java/J2EE and related technologies, including Spring Framework and Hibernate JPA. Experience in developing reusable APIs and consuming web services (REST), as well as processing data formats like XML/JSON. Expert knowledge of Agile/Scrum/Kanban development methodologies and experience with databases (Oracle, Postgre, MongoDB). Extensive knowledge of CI/CD deployment pipelines, including Jenkins, Docker, shell scripting, and GIT with Unix proficiency. Nice to Have Experience in JavaScript frameworks such as ReactJs, Node JS, Angular, and jQuery. Familiarity with JavaScript build tools and dependency management. Experience in creating responsive designs using frameworks like Bootstrap. Knowledge of GCP, GKE, AWS is an advantage. Experience or knowledge in system architecture and solution design. Hands-on experience in Python, Machine Learning, and Data Science.

🏢 Summary: Senior Frontend Developer role for a greenfield international project focused on enterprise-grade frontend applications using React and TypeScript. The position involves building advanced UI solutions, integrating APIs, and supporting explainable, auditable workflows in a hybrid B2B setup. Teams work cross-functionally following API-first and event-driven development principles. 🗂️ Requirements: Senior-level frontend development experience, Strong knowledge of React, Strong knowledge of TypeScript, Experience building complex enterprise-grade applications, Hands-on API integration experience, Familiarity with contract-first or API-first development, Experience creating reusable components, Experience working with design systems, Understanding of accessibility standards, Knowledge of responsive design, Knowledge of performance optimisation, Knowledge of usability principles, Experience with frontend testing, Ability to work in cross-functional teams, Strong quality and validation mindset, Fluent Polish, Fluent English 📃 Skills: React, TypeScript, API, HTML, CSS, JavaScript, Testing, Accessibility, Responsive, Performance, DesignSystems 🏢 Description: Cooperation Details Start date: As soon as possible, within 3–4 weeks Contract duration: 12 months initially, with possible extensions Contract type: B2B Working model: Hybrid, with 2 days per week from the Warsaw office and the remaining days remotely Equipment: Laptop provided by the client Travel: Up to one possible business trip per year to the Netherlands or France (paid by the Client) Languages: fluent Polish and English are a must We are looking for a Senior Frontend Developer to join a new initiative delivered for an international client operating in the information services sector. Both projects are greenfield initiatives developed from scratch. Each team will consist of approximately five people, including a Tech Lead, Backend Developer, Frontend Developer, and QA Engineer. Responsibilities Developing frontend applications using React and TypeScript. Building advanced enterprise-grade user interfaces, including dashboards, forms, filters, cards, and drill-down views. Integrating frontend applications with APIs using a contract-first approach. Designing and developing reusable components and solutions based on a design system. Ensuring accessibility, responsiveness, performance, usability, and overall application quality. Implementing explainability-focused UI patterns, including evidence, rationale, confidence levels, and source traceability. Building human review workflows that support approval, rejection, and manual override of system recommendations. Collaborating closely with the Tech Lead, Backend Developers, QA Engineers, and other team members. Contributing to component, UI integration, and regression testing. Working according to spec-driven development, API-first, and event-driven delivery principles. Ensuring auditability, traceability, and explainability by design. Supporting thin vertical slice and steel-thread delivery to validate end-to-end functionality early in the development process. Requirements Senior-level experience in frontend software development. Strong practical knowledge of React and TypeScript. Experience in building complex enterprise-grade applications and user interfaces. Hands-on experience with API integration. Familiarity with contract-first or API-first development. Experience in creating reusable components and working with design systems. Good understanding of accessibility, responsive design, performance optimisation, and usability. Experience with frontend components, integration, and regression testing. Ability to work effectively in a cross-functional product team. Strong quality and validation mindset from the beginning of the development lifecycle. Fluency in Polish and English. Experience in projects involving AI, agentic workflows, human-in-the-loop governance, explainability, or decision-support systems will be considered an advantage.

🏢 Summary: Frontend role focused on building and enhancing secure API integrations with external brokers using React and TypeScript in a hybrid B2B model. The position involves developing reusable UI components, collaborating with backend teams on financial API integrations, and contributing to code quality in a Scrum environment. 🗂️ Requirements: Experience in frontend development, Proficiency in React, Proficiency in TypeScript, Knowledge of REST APIs, Knowledge of JSON, Ability to work in Scrum teams, Experience with performance standards, Experience with accessibility standards, Collaboration skills, Communication skills 📃 Skills: React, TypeScript, REST, JSON, Scrum, Node.js, CI/CD, Postman 🏢 Description: General info: - Model of work: hybrid, 1x per week work from office in Warsaw - Type of contract: B2B contract - Rate: 130 PLN net + VAT / hour Introduction & Summary: Role requires expertise in frontend development to create and enhance API integrations with external brokers. Ideal candidate should have a strong proficiency in React and TypeScript. You will contribute to building user-friendly and secure interfaces, ensuring smooth integration with partners while adhering to high-quality standards. Main Responsibilities: - Develop reusable, high-quality React + TypeScript components for plugins and internal tools - Work closely with backend engineers to integrate with payment and financial APIs - Ensure performance, accessibility, and responsiveness on partner websites - Contribute to code quality through testing and code reviews - Participate in two-week sprints using Scrum methodology - Collaborate with the Product Owner for requirement clarification - Engage in continuous learning and knowledge sharing within the team Key Requirements: - Proven experience in frontend development - Proficiency in React and TypeScript - Familiarity with REST APIs and JSON - Ability to work in Scrum teams - Experience with performance and accessibility standards - Good collaboration and communication skills Nice to Have: - Knowledge of Node.js - Experience with CI/CD pipelines - Familiarity with tools like Postman - Experience in building embeddable widgets/plugins - Understanding of security and compliance in financial products

🏢 Summary: Tech Lead role focused on architecting and leading development of Risks & Inspections and Safety Intelligence solutions using .NET, C#, and React in an enterprise SaaS environment. The position involves backend engineering, API design, event-driven architecture, and technical leadership within a hybrid B2B contract setup. The project includes collaboration across domains with emphasis on secure, spec-driven, and scalable development practices. 🗂️ Requirements: Deep knowledge of .NET architecture, Deep knowledge of C# architecture, Experience with REST API design, Experience with OpenAPI, Expertise in React, Strong understanding of event-driven architecture, Experience in spec-driven development, Ability to lead technical projects and teams, Proficiency in English, Availability for hybrid work in Warsaw 📃 Skills: .NET, C#, REST, OpenAPI, React, SaaS, APIs, MDM 🏢 Description: Details: Team Structure : Team of 5, including the tech lead, backend, frontend, QA, and SME. Contract : B2B - 12 months contract with possible extensions. Set up: Hybrid - 2 days/week in the Warsaw’s office, rest remote. Start Date : ASAP, ideally within 3-4 weeks. Travel : Possibly one trip during the year to Netherlands or France Language Requiremen t: Proficiency in English. Summary The primary purpose of the Tech Lead role is to guide the development of a project focusing on Risks & Inspections and Safety Intelligence. This position is crucial for ensuring the architecture and backend engineering align with industry standards and project goals, leading a small team while overseeing technical delivery and stakeholder collaboration. Main Responsibilities: Architect .NET / C# solutions and oversee backend engineering. Design APIs using contract-first approach with REST and OpenAPI. Ensure React-based enterprise SaaS applications align with business requirements. Implement event-driven architecture and manage workflow orchestration. Lead spec-driven development ensuring quality and traceability. Manage authorization, auditability, and secure design practices. Facilitate human-in-the-loop controls within agentic workflow patterns. Align capabilities across multiple domains including MDM, audit, and APIs. Provide technical leadership and manage delivery planning and risk assessment. Key Requirements: Deep knowledge of .NET / C# architecture. Experience with REST and OpenAPI design. Expertise in React for enterprise SaaS applications. Strong understanding of event-driven architecture. Experience in spec-driven development practices. Capability to lead technical projects and teams. Nice to Have: Experience with agentic workflow understanding. Familiarity with human-in-the-loop governance principles. Knowledge of auditability and traceability by design. Background in cross-capability collaboration.

🏢 Summary: B2B role for a Senior Fullstack Developer to design and build enterprise fintech applications using Angular 17+ and Node.js, with strong .NET and Azure integration. The position involves developing scalable front-end and back-end solutions, ensuring security, performance, and high code quality across cloud-based environments. Work is hybrid with occasional business travel. 🗂️ Requirements: Minimum 7 years of software development experience, Strong experience with Angular 17+ and TypeScript, Hands-on experience with Node.js, Proficiency in C# and .NET 8+, Experience with ASP.NET Core and Entity Framework Core, Experience with SQL Server and relational databases, Experience with Azure services including Azure AD, Experience with Docker and Kubernetes, Experience with CI/CD pipelines, Experience with unit and integration testing using Vitest, xUnit, Moq, Experience integrating RESTful APIs and external systems 📃 Skills: Angular, TypeScript, SCSS, HTML, Node.js, C#, .NET, ASP.NET, EntityFramework, SQL, SQLServer, Azure, AzureAD, Databricks, Docker, Kubernetes, CI/CD, Git, npm, REST, Vitest, xUnit, Moq, JSON, YAML 🏢 Description: Industry: Fintech Location: Hybrid Warsaw lor Gdańsk - 1-2 x month + twice a year, a one-week business trip to Munich. Assignment type: B2B Rates: 4-7 years exp: 138 PLN/h, 7-10 years exp.: 154 PLN/h, 10+ years exp: 167 PLN/h Summary: This role focuses on designing and developing enterprise applications, ensuring high-quality user interfaces and robust back-end systems, primarily using Angular and Node.js with experience in .Net and various cloud services. Main Responsibilities: Design and develop enterprise applications with Angular 17+ on the front end and Node.js on the back end. Experience with ASP.NET Core (.NET 8+) Implement standalone components and signals-based architecture for responsive, maintainable UIs. Integrate Azure MSAL authentication, RESTful APIs, and external system integrations. Build and optimize data access layers using Entity Framework Core and manage relational data in SQL Server. Ensure application security through authentication, authorization, and data protection using Azure AD. Deploy and manage environments using Docker, Kubernetes, and CI/CD pipelines. Write comprehensive unit and integration tests for both front-end (Vitest) and back-end (xUnit, Moq). Collaborate with cross-functional teams to maintain shared libraries and iterate on user feedback. Troubleshoot, debug, and optimize for scalability and performance across the stack. Key Requirements: Experience: minimum of 7 years as a developer. Front-End: Angular 17+, TypeScript, SCSS, HTML. Back-End: Node.JS, C#, .NET 8+, ASP.NET Core, Entity Framework Core, SQL Server. Languages & Formats: C#, SQL, JSON, YAML. Testing: Vitest, xUnit, Moq. Tools & Frameworks: Git, npm, RESTful APIs, Docker, Kubernetes, CI/CD pipelines. Cloud: Experience with Azure services (AD, SQL, Databricks). Nice to Have: Soft Skills such as Attention to Detail, Collaboration, Problem-Solving, and Learning Agility.

🏢 Summary: Senior Full Stack Developer role focused primarily on backend development with Python and FAST API, combined with React-based frontend work in a hybrid B2B model. The position involves designing scalable web applications, building high-performance APIs, and working with relational and NoSQL databases. Strong backend expertise is essential, with intermediate frontend skills and experience in modern DevOps practices. 🗂️ Requirements: 8+ years of professional software development experience, Expert proficiency in Python, Strong experience with FAST API, Strong knowledge of relational and NoSQL databases, Experience with SQLAlchemy ORM, Deep understanding of data structures and algorithms, Experience building RESTful APIs and microservices, Proficiency in writing unit and integration tests in Python, Strong knowledge of ReactJS and NodeJS, Experience with Redux or MobX, Familiarity with React Query, Experience with Material UI, CSS, and HTML, Experience with Jest and Cypress, Solid understanding of JavaScript and TypeScript 📃 Skills: Python, FASTAPI, SQLAlchemy, PostgreSQL, MySQL, MongoDB, DynamoDB, ReactJS, NodeJS, Redux, MobX, ReactQuery, MaterialUI, CSS, HTML, Jest, Cypress, JavaScript, TypeScript, Docker, Kubernetes, AWS, Azure, GCP, RabbitMQ, Kafka 🏢 Description: Working mode: Hybrid mode ( 2-3 days in a week from the office in Wroclaw or Warsaw) Experience Level: 8+ Years Contract Type: B2B About the Role We are looking for a highly skilled Senior Full Stack Developer with a primary focus on Python and FAST API to join the development team. The ideal candidate is a Python expert capable of architecting robust backend services. While React skills are required, we are flexible regarding the depth of frontend expertise (Intermediate level is acceptable), provided the backend strength is exceptional. Key Responsibilities Backend Architecture: Design, develop, and maintain scalable web applications using Python and FAST API . API Development: Build high-performance RESTful APIs and microservices, ensuring low latency and high availability. Database Management: Work with relational and NoSQL databases, utilizing ORMs like SQLAlchemy to design efficient database schemas and queries. Frontend Development: Develop and maintain user-facing features using ReactJS , ensuring the technical feasibility of UI/UX designs. Code Quality: Write clean, maintainable, and testable code; perform unit testing to ensure robustness. DevOps: Implement and manage CI/CD pipelines to streamline deployment processes. Collaboration: Work closely with cross-functional teams (Product, QA, and Design) in a hybrid working environment. Mandatory Technical Skills 1. Backend (Core Strength): Languages: Expert proficiency in Python . Frameworks: Strong experience with FAST API (Must-have). Experience with SQLAlchemy is highly preferred. Fundamentals: Deep understanding of data structures, algorithms, and space-time complexity. Database: Strong understanding of Relational (e.g., PostgreSQL, MySQL) and NoSQL (e.g., MongoDB, DynamoDB) databases. Testing: Proficiency in writing unit tests and integration tests for Python applications. 2. Frontend (Intermediate Level): Libraries: Strong knowledge of ReactJS and NodeJS . State Management: Experience with React workflows such as Redux or MobX . Tooling: Familiarity with React Query . Styling: Experience with Material UI , CSS , and HTML . Testing: Experience with frontend testing tools like Jest and Cypress . JavaScript: Solid understanding of JavaScript , TypeScript , and browser rendering behavior. Good to Have Experience with cloud platforms (AWS, Azure, or GCP). Knowledge of containerization (Docker, Kubernetes). Understanding of microservices architecture and message queues (RabbitMQ, Kafka).