Senior Mendix Developer (f/m/x)

Sii Poland; Lublin; On-site; PLN 180,000 - 260,000; Full time

Benefits offered by this job

Great Place to Work

Profit sharing

Medical care

Centre of internal trainings

Contracts with the biggest brands

Open and accessible management team

Regular integration events and trips

Comfortable and well-equipped offices

MySii app

Job summary

Sii Poland is seeking an experienced Senior Mendix Developer to design, build, test, and deploy enterprise Mendix applications in a hybrid setup. You will collaborate with business analysts, architects, testers, and international stakeholders to deliver scalable, secure solutions.

You will optimize domain models, microflows, and UI/UX, integrate with external systems using REST/SOAP/OData, and contribute to documentation and deployment guides.

Qualifications

• 4+ years of IT experience, with at least 2–3 years in Mendix development.
• Strong Mendix Studio Pro and Mendix Cloud skills.
• Experience with relational databases such as SQL Server, PostgreSQL, or Oracle.
• Understanding of microservices architecture and UI/UX principles.
• Familiar with Agile/Scrum methodologies and DevOps practices.
• Fluent Polish.
• English at least B1.

Responsibilities

• Design and develop enterprise Mendix applications.
• Create and optimize domain models, microflows, nanoflows, and UIs.
• Integrate Mendix with external systems via REST, SOAP, OData.
• Translate business requirements into prototypes and scalable Mendix solutions.
• Debug, troubleshoot, and optimize performance for scalability and security.
• Implement workflows and digital solutions to improve efficiency.
• Develop custom widgets and microservices to extend Mendix.
• Perform unit, integration, and user acceptance tests.
• Create and maintain architecture diagrams and deployment guides.

Skills

Mendix development

Agile/Scrum

DevOps practices

Polish language

English language (B1)

Tools

Mendix Studio Pro

Mendix Cloud

SQL Server

PostgreSQL

Oracle

REST/SOAP/OData

Job description

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 tasks

• 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

Requirements

• 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

Nice to have

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

Job no. JOB-YZLAR

Sii ensures that all hiring decisions are made solely on the basis of qualifications and competence. We are committed to equal and fair treatment of all, regardless of legally protected characteristics. At Sii, we promote a diverse and inclusive work environment, in full compliance with applicable anti-discrimination laws.

Benefits For You

• Great Place to Work
• Solid financial situation
• Contracts with the biggest brands
• Centre of internal trainings
• Many experts you can learn fromOpen and accessible management team
• Profit sharing
• Passion Sponsorship program
• Regular integration events and trips
• Comfortable and well-equipped offices
• MySii app
• Medical care