Senior .NET Developer, Tickets Selling System

🏢 Summary: Senior .NET backend role modernizing and expanding a complex international rail-ticket sales platform. The work focuses on scalable microservices, REST APIs, cloud-hosted components, and collaboration on new features across cross-functional teams. 🗂️ Requirements: 7+ years of backend development experience, 7+ years of commercial .NET development experience, C# and .NET development experience, Clean Code and OOP expertise, WebAPI knowledge, Microservices architecture understanding, Unit testing and mocking framework experience, Dependency injection experience, Entity Framework or NHibernate knowledge, DBMS experience, SOLID principles understanding, Agile methodology understanding, Good spoken English 📃 Skills: .NET, C#, Microservices, REST, WebAPI, MSSQL, PostgreSQL, DynamoDB, AWS, NUnit, Moq, Autofac, EntityFramework, NHibernate, OOP, SOLID, Agile, JWT, OAuth, OpenID 🏢 Description: Client The company is one of the regional leaders in the industry and is currently launching their new product, an international platform for ticket sales. The company's annual income exceeds 100 million euros. Join a great company, not merely an individual project Project overview The client uses various tools to reach their customers, such as a mobile app, a responsive web application, or communicating with them directly through the call center. The system is very complex, it must comply with a large number of regulations. We provide APIs for different clients including the biggest Global Distribution Systems (GDSes). Our client is committed to ensuring that the system will be as modern as possible. It is based on microservice architecture with the use of continuous integration, where a few hundred components operate independently of each other and can be used as they become available. This increases the modularity of the system and optimizes the use of the services. All components run on AWS. Team Several independent teams are working on the project. The goals of each team are limited to the part of the system they're working on. DataArt's specialists are working on the back-end in one of the teams. Position overview DataArt is currently helping to modernize and develop the IT system of an independent online retailer of railroad tickets. Technology stack .NET (always working with newest versions) microservices REST API MSSQL migrating to Postgres, DynamoDB Responsibilities Refactoring and expanding tickets selling system Develop, enhance, and maintain high-quality, scalable code Work collaboratively with cross-functional teams to support the implementation of new features and achieve their objectives Requirements 7+ years of backend development experience 7+ years of experience in commercial software development on the .NET platform Understanding of and experience working with C# Development experience with .NET Strong skills in Clean Code and OOP Knowledge of WebAPI Understanding of microservices architecture Experience with unit testing (like nUnit) and mocking frameworks (preferred Moq) Experience with dependency injection (preferred Autofac) Knowledge of Entity Framework or NHibernate Experience working with any DBMS system Understanding of SOLID principles Understanding of Agile development methodology Good spoken English Nice to have Knowledge of basic Authentication: types of Authentication, JWT, OAuth 2.0, OpenId Connect What We Offer: Vacation days : Up to 26 business days per year. 10 illness/special days off per year (fully paid, no medical papers needed) for all contract types Health and life insurance (Luxmed) MyBenefit platform with Multisport option Internal psychological support service English language classes from the first working day Access to external learning platforms : O’Reilly, LinkedIn Learning, Udemy, and a wide catalog of diverse internal training Flexible workplace : work from the office, from home, or choose a hybrid option Tech Skills Mentoring Program Opportunities to develop as a public speaker, mentor, or technical interviewer Fully paid idle (bench) when not involved in a project Certification reimbursement (AWS, GCP, Microsoft, etc.)

🏢 Summary: Technical Architect role leading the modernization of a large investment-management platform from Azure to AWS. The position owns end-to-end architecture for cloud-native Java microservices, including domains, APIs, security, eventing, infrastructure, and delivery governance. 🗂️ Requirements: 15+ years of Java development experience, 4+ years in architecture or technical leadership, Microservices, DDD, event-driven and cloud-native architecture expertise, Java 21+, Micronaut or Spring Boot, Hibernate/JPA, MyBatis and Gradle, CQRS and event-sourcing design over relational databases, Aurora PostgreSQL or managed RDBMS design, migrations, pooling and IAM authentication, AWS EKS, RDS, IAM, Secrets Manager, ECR, CloudWatch and X-Ray, API gateway architecture and operations, Azure B2C OIDC/JWT or AWS Cognito authentication flows, Terraform, Argo CD and Helm hands-on experience, GitHub Actions or equivalent CI/CD pipeline design, Security architecture: IAM, zero-trust, encryption at rest and in transit, OpenTelemetry, distributed tracing and structured logging, English architecture documentation and stakeholder communication 📃 Skills: Java, Micronaut, Spring, Hibernate, JPA, MyBatis, Gradle, AWS, EKS, RDS, Aurora, PostgreSQL, Flyway, Liquibase, Terraform, ArgoCD, Helm, GitHub, Kong, IAM, Cognito, Azure, OIDC, JWT, OpenTelemetry, GraphQL, CQRS, DDD, KMS, TLS, ECR, CloudWatch, XRay 🏢 Description: Project overview DataArt's team is assisting a client, part of one of the largest investment management organizations in the world in migrating their existing services and applications to AWS, as well as developing new greenfield platforms. The engagement covers full-platform modernization: decomposing a monolithic Azure-based legacy system into cloud-native microservices, establishing domain-driven data ownership, and building new institutional client-facing solutions. By participating in this project, you will directly shape the architectural direction of a large-scale, high-stakes migration. Position overview As a Technical Architect, you will own the end-to-end architectural decisions for a portfolio of Java microservices on AWS. You will define domain boundaries, data models, API contracts, security standards, and event messaging topology. You will work closely with Engineering Managers, Delivery Managers, and cross-functional product teams to translate business requirements into scalable, maintainable platform designs and ensure those designs are faithfully implemented by delivery teams. Technology stack Java (Amazon Corretto), Micronaut, Gradle, Hibernate, MyBatis, Aurora PostgreSQL, Flyway, AWS EKS, Argo CD, Terraform, GitHub Actions, Kong API Gateway, AWS IAM / Secrets Manager, OpenTelemetry, Azure B2C, AWS Cognito, E-Hub (pub/sub). Responsibilities Define and own the target architecture for cloud-native Java microservices, applying Domain-Driven Design (DDD) principles bounded contexts, aggregate roots, domain events. Design CQRS-style read/write separation over relational stores (GraphQL composition + ORM read paths, Hibernate write path). Establish and govern the event-driven messaging topology: pub/sub patterns, event contracts, consumer group design, and coexistence strategies during Azure → AWS migration. Architect security-first persistence: credential-free AWS IAM database authentication, KMS encryption at rest, TLS in transit, least-privilege DB roles. Define identity and authentication patterns using Azure B2C (OIDC/JWT) and AWS Cognito across different user personas (admin, organization, end-user). Design and oversee the API gateway layer (Kong): routing, OIDC plugin integration, rate limiting, and zero-downtime consumer cutover during migration. Own the infrastructure architecture: EKS cluster design, Helm chart standards, Argo CD GitOps pipeline, Terraform module structure per environment (dev / test / stage / prod). Conduct architecture reviews and produce solution design documentation that serves as the authoritative reference for delivery teams. Mentor senior engineers and tech leads; raise architectural maturity across the program. Stay current with industry trends including AI tooling to ensure solutions remain innovative and competitive. Requirements 15+ years of professional experience in Java development, with at least 4 years in an architecture or technical leadership role. Deep expertise in microservices architecture, DDD, event-driven systems, and cloud-native design principles. Strong hands-on knowledge of Java (21+), Micronaut or Spring Boot, Hibernate / JPA, MyBatis, and Gradle. Proven experience designing and delivering CQRS / event-sourcing patterns over relational stores. Experience with Aurora PostgreSQL (or equivalent managed RDBMS): schema design, migrations (Flyway or Liquibase), connection pooling, and IAM-based authentication. Solid understanding of AWS platform services: EKS, RDS, IAM, Secrets Manager, ECR, CloudWatch, X-Ray. Experience with API gateway design and operation (Kong, AWS API Gateway, or equivalent). Familiarity with identity platforms: Azure B2C (OIDC/JWT) and/or AWS Cognito for multi-persona authentication flows. Hands-on experience with Infrastructure as Code (Terraform) and GitOps delivery (Argo CD, Helm). Experience with CI/CD pipeline design using GitHub Actions or equivalent. Strong understanding of security architecture: IAM, zero-trust patterns, encryption at rest and in transit. Observability experience: OpenTelemetry instrumentation, distributed tracing, structured logging. Excellent communication skills in English, able to produce clear architecture documentation and present to both technical and non-technical stakeholders. Strong problem-solving skills and a proactive, outcome-driven attitude. Nice to have Experience in the finance or investment management industry. AWS certifications (Solutions Architect Professional, Developer). Experience with Azure Service Bus and hybrid Azure → AWS EventBridge migration patterns. Micronaut GraphQL module (read-only schema over normalized relational store). Aurora PostgreSQL temporal / history-table patterns. Familiarity with Kong as the API gateway for platform-wide API governance. Experience with graph data structures in relational stores (adjacency / entity-node / relations patterns). What We Offer: Vacation days : Up to 26 business days per year. 10 illness/special days off per year (fully paid, no medical papers needed) for all contract types Health and life insurance (Luxmed) MyBenefit platform with Multisport option Internal psychological support service English language classes from the first working day Access to external learning platforms : O’Reilly, LinkedIn Learning, Udemy, and a wide catalog of diverse internal training Flexible workplace : work from the office, from home, or choose a hybrid option Tech Skills Mentoring Program Opportunities to develop as a public speaker, mentor, or technical interviewer Fully paid idle (bench) when not involved in a project Certification reimbursement (AWS, GCP, Microsoft, etc.)

🏢 Summary: Join a DevOps-focused .NET integration squad responsible for designing, implementing, securing, and operating integration products across on-premises, private-cloud, and public-cloud environments. The role covers .NET framework expertise, application configuration, CI/CD, deployment troubleshooting, performance optimization, and compliance in a regulated IT environment. 🗂️ Requirements: Hands-on Azure engineering experience, C# and .NET application development experience, Visual Studio and Azure DevOps experience, Microsoft security expertise in Windows Server environments, Kerberos and Active Directory knowledge, CI/CD concepts knowledge, PKI and certificate concepts knowledge, Azure services experience, Windows Server 2016, 2019, and 2022 experience, PowerShell experience, Experience with .NET 4.8, .NET 8, ADFS, MVC, IIS, WCF, WebAPI, NuGet, and APIs, Integration patterns and technologies knowledge, API security integration experience, Security, encryption, token-based authentication, GDPR, and compliance knowledge, Middleware and advanced IT infrastructure experience, Scrum and Agile familiarity, Risk management knowledge 📃 Skills: Azure, C#, .NET, VisualStudio, AzureDevOps, WindowsServer, Kerberos, ActiveDirectory, CICD, PKI, PowerShell, ADFS, MVC, IIS, WCF, WebAPI, NuGet, APIs, GDPR, Scrum, Agile, Middleware, OAuth, OpenID, SAML, Linux, ServiceFabric, Splunk 🏢 Description: Division: Group Technology Services (GTS) About the squad: Join the ".Net Application Integration Services" squad, consisting of 1 Product Owner, 1 Scrum Master, and 10 developers. We manage several products on-premise, in Private and Public Cloud, mainly including: Bespoke C# .Net Libraries delivered as NuGet Security token services for Web based, API and Message based applications Cloud resources, middleware (runtime, hosting), Service Mesh… Our main collaborators are Euroclear software developers, system administrators, and solution architects.We prioritize integration, solving, and optimization to ensure high availability, scalability, and reliability. We also collaborate with security teams to implement vital security measures and ensure data protection. About the role: As a developer in our squad, you will focus on DevOps: Subject Matter Expert for .Net framework Analyze requirements and solutions, design, implement, and integrate our products. Drive and contribute to Application Change in a regulated IT organization Main Tasks Learn our products and adopt a T-Shaped skillset. Maintain .Net framework configuration, technical security baseline and manage the relationship with Microsoft for incident and advisory cases. Manage and optimize application configuration. Collaborate with cross-functional teams to ensure seamless integration and delivery of solutions. Troubleshoot and resolve issues related to deployment and integration in a timely manner. Provide technical guidance and support to our clients. Perform thorough testing, monitor and optimize the performance of integration solutions. Ensure compliance with data privacy regulations and internal governance policies. Maintain pragmatic documentation of integration for reference by development teams and stakeholders. Key Qualifications Integration Expertise: Comprehensive understanding of various integration patterns, approaches, and technologies Web Development: Proficiency in web development technologies and frameworks API Security Integration: Experience in integrating API security measures Security and Compliance: Understanding of security best practices, encryption, token-based authentication, and compliance requirements (e.g., GDPR) Problem Solving and Troubleshooting: Strong analytical skills to identify and resolve complex integration challenges .Net Application Development: Experience in .Net application development and testing Scrum Framework and Agile Methodologies: Familiarity with Scrum and Agile practices Middleware Experience: High experience in Middleware Advanced IT Infrastructure: Security-focused with experience in advanced IT infrastructure Independent and Team-Oriented: Ability to work independently with a strong team mindset and a focus on quality Risk Management Expertise: Strong understanding of risk management principles, methodologies, and tools. Ability to identify, assess, and mitigate various types of risks, including operational, financial, strategic, and compliance risks Mandatory Skills Azure hands-on engineering experience in .Net c# Application development , Visual Studio, Azure DevOps Microsoft Security in Windows Server environment, including Kerberos and Active Directory CICD concepts Understanding of PKI concepts and Certificates Experience with Azure services Windows Server 2016, 2019, 2022 PowerShell, .Net 4.8, .Net 8, ADFS, MVC, IIS, WCF, WebAPI, NuGet, APIs Nice to Have OAuth, OpenID Connect, and SAML .Net8 and/or Java integration on Linux Service Fabric Splunk If you have the required qualifications and are eager to join a squad with ambitious challenges, apply now! This is a great opportunity! Please note that this is a permanent position, and we do not offer freelance/contract arrangement for the role. About Us Why join us Embark on your new adventure at Euroclear, and work at the heart of the global capital markets. We connect over 2,000 financial institutions across the globe. As an open and resilient infrastructure, we contribute to the stability of the financial markets. We help clients cut through complexity, lower costs, and mitigate risks of financial transactions. At Euroclear, we have the clear ambition to use our key role to facilitate and accelerate a sustainable global financial system. What We Offer: Work closely with inspiring, supportive and engaged colleagues from more than 80 different countries. Practice your talents in a highly professional international environment. Join a learning and development environment with an emphasis on knowledge sharing and training. Competitive salary and comprehensive benefits. Ways of working Find your own optimal balance within our hybrid working model, where you can connect at the office 8 days a month and also benefit from remote working. Great Place to Work for All We are committed to creating an inclusive culture that celebrates diversity and strives to be a Great Place to Work for All. All qualified applicants will be considered for employment, regardless of any aspect that makes them unique (including race, religion, national origin, gender, sexual orientation, age, marital status, pregnancy, disability, ...). If you need any specific accommodation due to disability or any other reason, you can let the recruiter know during your application process. Our values guide how we work together and shape our future: Our mission and values - Euroclear About the Team Group Technology Services (GTS) plans, builds and runs the global infrastructure of Euroclear, and is additionally responsible for the IT service management to the operating entities of the various Group markets. Group Technology Services operates its IT systems and IT services in such a way that, at an appropriate and benchmarked cost level, it can deliver the agreed levels of service to support the requirements of the business processes, for both normal operations and during disaster recovery.

🏢 Summary: Senior frontend/full-stack developer role focused on building resilient, enterprise-ready product features for a sports and health platform. The position involves React, TypeScript, Next.js, REST APIs, PostgreSQL, and close remote collaboration, with a hybrid schedule in Kraków. 🗂️ Requirements: 5+ years of professional development experience, Production experience with React and TypeScript, Production experience with Next.js App Router, REST API and data-validation experience, PostgreSQL and ORM experience, Ability to follow architectural documentation and team conventions, Git, code review, and Jira experience, Independent problem analysis and written feature planning/ADRs, Careful handling of healthcare data, schemas, and access logic, Strong written technical communication, Remote and asynchronous collaboration skills, Advanced English, Ability to complete a technical coding test without assistance, Availability to start within one month, Ability to work from the Kraków office 3 days per week 📃 Skills: React, TypeScript, Next.js, REST, Zod, PostgreSQL, Drizzle, Prisma, TypeORM, Git, Jira, Claude 🏢 Description: About the role You will be assisting in the understanding of, architecture, implementation, and quality of core Product Roadmap items intended to drive the project for our client forward. The ability to work with the team and collaborate is essential. You will have an immediate impact and be an early figure in the company today to help drive our growth. You will focus on solidifying our product and making it resilient as well as learning how to roll out enterprise-ready features. Required skills /knowledge and production experience/ React + TypeScript Next.js (App Router) — routing, server/client components, API routes REST API, data validation (example - Zod) PostgreSQL and ORM (Drizzle or similar — Prisma/TypeORM) Work according to the team's conventions and architectural documentation(ADR-y) — the ability to read and follow established standards before writing code Git, code review, ticketing (Jira) Coding with Claude /on daily basis/ Minimum of 5 years of professional experience developer with hands-on skills. Communication and other required skills Git, code review, ticketing (Jira) Independence in problem analysis and a willingness to plan before implementation (the project requires a written plan/ADR before each new feature). Accuracy and attention to detail—working with healthcare data requires caution when changing the schema and access logic. Good written communication—documentation, PR descriptions, tickets, and code review comments. Comfortable working in a distributed/remote team and asynchronous communication. Openness to feedback and a willingness to propose simpler solutions instead of over-engineering (the project explicitly avoids over-engineering). Sense of responsibility (ownership) for the delivered functionalities from design to implementation. Advanced English - hard must - daily calls with native CTO or CEO(weekly) . Ability to discuss technical problems, describe concept, architecture or planned feature. There's going to be (online or onsite in Krakow) technical coding test (without extra help) and English general and/or tech conversation. Awesome but not a must: Supabase (Auth, RLS, Postgres) AWS: S3, SQS, Lambda - designing or integrating with data processing pipelines (multipart upload, task queuing, workers) Terraform / IaC - ability to read infrastructure definitions (no need to write them yourself) Working with video / media data / large-volume files (e.g., recording processing, LiDAR, wearable data) Designing permission systems (RBAC) for multiple user roles OpenAPI / API contracts, documenting endpoints Experience in health, sports, telemedicine, or other sensitive/regulated data Application observability (Sentry, PostHog, or similar) Real-time integrations (chat/video SDKs like CometChat, WebSocket) Our benefits: Awesome and highly intense product /sports and health/ Private medical care and multisport card Flexible working hours (you can start between 8:00 -10:00 a.m.) Your choice of computer: Mac OS/Linux/Windows Upskilling budget English discussion classes every week Parking spot few mins from office Employee recommendation program. 🟢 The office is based in Kraków. We work 3 days from the office a week. 🟢 The process consists of 2 stages. We recruit remotely :) Ideal candidate should start within a month (no longer).

🏢 Summary: Oferta dotyczy rozwoju i utrzymania platformy B2B/B2C oraz aplikacji wewnętrznej dla branży automotive. Rola obejmuje tworzenie funkcjonalności, rozwój stosu technologicznego, wykorzystywanie AI oraz realny wpływ na produkt w zwinnym zespole. 🗂️ Requirements: Doświadczenie w projektach automotive, Minimum 7 lat programowania w PHP, Znajomość PHP 8.2 lub nowszego, Aktywne wykorzystanie narzędzi AI i krytyczna ocena generowanych rozwiązań, Znajomość Git, Znajomość OOP, Znajomość Docker, Doświadczenie z MySQL lub MariaDB, Znajomość zagadnień bezpieczeństwa, Znajomość języka angielskiego umożliwiająca komunikację i pracę z dokumentacją techniczną, Analityczne myślenie, Umiejętność pracy zespołowej, Gotowość do obecności w biurze raz na 2 tygodnie 📃 Skills: PHP, Git, OOP, Docker, MySQL, MariaDB, ChatGPT, Copilot, Cursor, Claude, Security, Yii2, REST, Vue3, Jira, Linux 🏢 Description: Pracujemy nad platformą B2B / B2C oraz aplikacją wewnętrzną rozwijaną dla klienta z branży automotive. Projekt jest realizowany przez doświadczony zespół specjalistów, wspierany przez zespół testerski. Pracujemy zwinnie, stawiając na nowoczesne narzędzia, sprawną komunikację oraz odpowiedzialność za powierzone zadania. Twój zakres obowiązków Szukamy osoby, która nie ogranicza się do realizacji ticketów, ale potrafi spojrzeć szerzej: Rozumie całość produktu, Myśli o wartości dla użytkownika i biznesu, Szuka sposobów na usprawnienie pracy zespołu, Wykorzystuje AI i nowoczesne narzędzia do szybszego i lepszego dowożenia efektów. Chce przejmować odpowiedzialność i mieć realny wpływ na produkt, który tworzymy. Czekające Cię wyzwania:  Będziesz odpowiedzialny/a za utrzymanie aktualnych oraz tworzenie od podstaw nowych funkcjonalności, a także za wdrażanie nowych technologii (rozwój stosu technologicznego). Nasze wymagania Doświadczenie w projektach automotive. Aktywne wykorzystywanie narzędzi AI (np. ChatGPT, GitHub Copilot, Cursor, Claude) do zwiększania jakości i efektywności swojej pracy oraz umiejętność krytycznego oceniania generowanych rozwiązań. Bardzo dobra umiejętność programowania w PHP (minimum 7 lat doświadczenia) – znajomość w wersji >=8.2 Znajomość systemu kontroli wersji GIT. Znajomość zagadnień związanych z OOP. Znajomość Docker. Doświadczenie z bazami danych MySQL/MariaDB. Umiejętności analitycznego myślenia, kreatywność. Solidność, zaangażowanie, umiejętność pracy w zespole. Znajomości języka angielskiego w stopniu pozwalającym na komunikację i korzystanie z dokumentacji technicznej. Znajomość zagadnień security. Mile widziane Produktowe podejście do pracy — myślenie o całości rozwiązania, a nie tylko o realizacji pojedynczych zadań, Nastawienie na szybkie dostarczanie klientowi wartości biznesowej, Umiejętność proponowania lepszych rozwiązań technicznych i produktowych, Chęć realnego wpływu na projekt i jego rozwój. Znajomość narzędzi do testowania penetracyjnego aplikacji webowych. Znajomości środowiska Linux i/lub administracji serwerem Linux. Znajomość frameworka Yii2, Znajomość zagadnień REST API. Znajomość Vue3. Doświadczenie w pracy z Jira. Obecność w biurze raz na 2 tygodnie. To oferujemy Atrakcyjne warunki współpracy, adekwatne do umiejętności i posiadanego doświadczenia. Współpracę z doświadczonym, sprawnym i zaangażowanym zespołem. Ciekawy i perspektywiczny projekt dla lidera w swojej branży. Szybki i przyjazny proces rekrutacyjny. Możliwość pracy zdalnej i hybrydowej (obecność w biurze raz na 2 tygodnie). Klimatyzowane biuro w Gliwicach. Wspaniałą atmosferę i zgrany team - imprezy integracyjne, gry i konkursy, wspólne wyzwania sportowe. Pakiet benefitów pracowniczych: pakiety Luxmed i Multisport, pakiety Polsat Box Go. Możliwości rozwoju: udział w szkoleniach, konferencjach, wymianie wiedzy.