Hastee, a Zellis company, is an award-winning fintech start-up providing a market-leading financial well-being solution.
The platform allows workers to get paid flexibly at any time of the month, provides money management and budgeting support, and helps them save sustainably.
The company operates in a B2B2C model, selling its solution to major employers who offer the Hastee app as a corporate benefit to their staff.
The Senior Full Stack Developer will design, develop, and maintain scalable and high-performing web applications using .NET (C#, ASP.NET Core) for the backend and React for the frontend.
Responsibilities include developing and consuming RESTful APIs, writing clean and efficient code, collaborating with product managers and designers, building reusable React components, contributing to database design, participating in code reviews, and troubleshooting software defects.
Requirements:
A minimum of 5+ years of professional experience as a Full Stack Developer is required.
Strong proficiency in C# and .NET Core/.NET 8 is essential.
A solid understanding of web development principles, including RESTful APIs, HTTP, and security best practices, is necessary.
Extensive experience with React and its core principles is required.
Experience with HTML, CSS, and modern JavaScript (ES6+) is needed.
Familiarity with database systems such as SQL Server, PostgreSQL, MySQL, and ORM frameworks like Entity Framework Core is important.
Strong communication skills and the ability to collaborate in a remote-first environment are essential.
Proficiency in English is required, and knowledge of Spanish is a plus.
Benefits:
The position offers a flexible work environment, allowing for hybrid or fully remote work in Spain.
There is an opportunity to work with cutting-edge technologies in a fast-growing fintech startup.
The company promotes a strong engineering culture focused on quality, scalability, and innovation.
Employees will be part of a supportive, diverse, and dynamic team that values growth and learning.
The role allows individuals to work on a product that makes a real social impact on financial well-being.
