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Java Developer (with Python proficiency) at Xfive. Location Information: Poland. At . xfive. , we are looking to expand our backend team with . a mid- to senior-level . engineer who brings . expertise in. . Java . and has a. basic+ working knowledge of Python . to help us deliver robust systems across a range of projects. In this full-time freelance role, you’ll do more than just code; you’ll communicate directly with clients and help shape the architecture of our solutions.. What We Offer. We’re all about building a team where you can thrive and do your best work. Here’s what you’ll love about working with us:. Freelance opportunity:. Enjoy the flexibility of a freelance contract and earn between . 25 . and. 35 USD . per hour, depending on your experience and expertise.. Room to grow:. We support continuous learning and professional development to help you advance your career.. Make an impact:. Your ideas and work will directly influence our direction and help drive meaningful change.. Diverse projects:. Work on exciting projects for startups, agencies, and companies based in the US, UK, and Australia.. Work your way:. Choose to work from home, your favorite coffee shop, or our Kraków office (we’ve got a nice parking space too!).. Set your schedule:. Work the hours that suit you best, as long as there's some overlap with the team and clients.. Transparency:. We’re open and honest about the company’s decisions, direction, and performance, so you’re always in the loop.. Supportive team:. You’ll never be left alone. Our team is collaborative and always ready to help each other.. Great vibes:. Join a team of open-minded, fun, and friendly people who enjoy what they do.. Stay connected:. Participate in social events, both online and in person, to stay engaged and build connections.. Must-Haves:. At least . 6 years of professional software development experience. , including:. 5+ years with Java Spring Boot. 2+ years with Python.. Strong verbal and written . English. communication skills (B2+ level), with the ability to talk directly with clients in online meetings.. Ability to deliver high-quality service and work independently.. Availability of . at least 40 hours per week. .. Solid. programming fundamentals. and understanding of best practices (e.g., DRY, KISS, abstraction, refactoring, optimization, security).. Strong understanding of software design patterns for scale and efficient code re-use.. Strong understanding of . Microservices with OpenAPI. ,. gRPC. , and. Protobufs. .. Java:. Strong command of . Java. and . Spring Boot.. Familiarity with . non-relational databases. like . MongoDB.. Experience building . RESTful APIs. and working with . microservices.. Understanding of . Java concurrency. and . multi-threading.. Experience with testing frameworks like . JUnit. and . Mockito.. Familiarity with . Spring Security. for authentication and authorization.. Proficiency with . build tools. such as . Maven. or . Gradle.. Experience with . containerization. (Docker) and . orchestration platforms. (e.g., Kubernetes).. Good understanding of . logging . and. monitoring tools. for Java apps (e.g., SLF4J, Logback, ELK stack).. Familiarity with . JVM performance tuning. .. Python: . Solid grasp of . Python 3.x . syntax, idioms, and best practices.. Strong. understanding . of . object-oriented. and . functional programming paradigms. in Python.. Familiarity with . virtual environments. and . dependency management tools. (venv, pip, Poetry).. Proficiency in . writing unit. and . integration tests. with pytest or unittest.. Comfortable . packaging modules. and . managing releases. (e.g., setuptools, wheel, PyPI).. Experience with . logging. , . debugging,. and . performance profiling. (cProfile, logging module).. Basic knowledge of . asynchronous programming.   with. asyncio. or . async libraries. Ability to work with databases via . ORMs. or . direct drivers.. Understanding of . API serialization. and . request validation. .. Nice-to-Haves:. Basic . Polish. proficiency (A2+level) to communicate with our local team.. Exposure to . task queues. and . concurrency tools.. Familiarity with . static typing. and . linting.. Experience containerizing Python applications.. Knowledge of . CI/CD workflows. for Python.. Hands-on with . data-processing libraries. (pandas, NumPy).