Senior Mendix Developer (f/m/x)

Expected, Mendix (Low‑Code Platform), PostgreSQL, Oracle Databases

Optional, Java, JavaScript, HTML, CSS3

About the project, We are looking for a skilled Senior Mendix Developer to join our team and contribute to the design, development, testing, and deployment of enterprise-grade applications using the Mendix low-code platform. You will work in a hybrid environment, collaborating closely with business analysts, architects, testers, and international stakeholders to create innovative solutions that enhance operational efficiency. If you are passionate about low-code development and eager to make a significant impact, this opportunity may be the right fit for you.

Your responsibilities, Designing and developing enterprise-grade applications using the Mendix low-code platform, Creating and optimizing domain models, microflows, nanoflows, and intuitive user interfaces, Implementing integrations with external systems, databases, and third-party APIs using REST, SOAP, and OData, Converting complex business requirements into functional prototypes and scalable Mendix solutions, Debugging, troubleshooting, and optimizing application performance to ensure scalability and security, Implementing workflows and digital solutions that improve operational efficiency, Developing custom widgets and microservices to extend Mendix functionality, Conducting unit, integration, and user acceptance testing, Creating and maintaining technical documentation, including architecture diagrams and deployment guides

Minimum 4 years of professional IT experience, with at least 2–3 years focused on Mendix development, Very good knowledge of Mendix Studio Pro and Mendix Cloud services, Experience with relational databases such as SQL Server, PostgreSQL, or Oracle, Understanding of microservices architecture and UI/UX principles, Strong familiarity with Agile/Scrum methodologies and DevOps practices, Fluent Polish required, Minimum B1 level of English required

Optional, Practical knowledge of Java, JavaScript, HTML, and CSS, Mendix Advanced or Expert certification

This is how we work, agile, scrum

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 – you can change them thanks to Job Changer application, 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

Recruitment stages, Send your CV, Talk to us about your expectations, Learn more about our projects and choose the best, Start your adventure with Sii!

Sii Sp. z o.o., Sii is the leading technology consulting, digital transformation, engineering, and business services vendor in Poland. We already employ more than 7 300 professionals and implement projects in a variety of industries for clients from many countries around the world. The Great Place to Work title, won 10 times in a row, proves that at Sii, we create a friendly work environment., , Sii ensures that all employment-related decisions are made solely on the basis of qualifications and competencies. We are committed to equal treatment of all individuals, regardless of any protected characteristics, and promoting a diverse and inclusive work environment.

This is how we work,