Fullstack .NET Developer

DropaCode; Wien; On-site; EUR 64,000 - 84,000; Full time

Job summary

DropaCode is seeking a Fullstack .NET Developer for an on-site assignment in Vienna, Austria, to design, develop and maintain secure integration components within an enterprise system environment.

The role focuses on .NET (C#) development, system interoperability and secure data exchange with external governmental and financial intelligence systems. On-site work only, freelance engagement with an initial 6 months.

Qualifications

• Minimum 5 years of professional software development experience.
• At least 3 years of hands-on C#/.NET development.
• Minimum 2–3 years of hands-on DevOps experience in enterprise environments.
• Experience in secure software development for sensitive data environments.
• Familiarity with POCO/DTO modelling and clean code principles.
• Experience with RESTful and SOAP services; secure integration patterns.

Responsibilities

• Analyze business and technical requirements provided by stakeholders and system architects.
• Review external system interfaces (APIs, databases, XML feeds) to determine the integration approach.
• Design integration solutions using .NET (C#) aligned with the system architecture.
• Define data flow between the platform and external systems, object models and mapping strategies, and the authentication and security approach.

Skills

C# (.NET)

DevOps

Secure development

RESTful APIs

SOAP APIs

OAuth 2.0/JWT

TLS/HTTPS security

POCO modelling/SOLID

JSON/XML serialization

English fluency

Education

Bachelor's degree in CS or related

Tools

AutoMapper

Job description

Fullstack .NET Developer

Client: Agency of the United Nations

Location: Vienna, Austria (On-site - no remote work allowed)

Type of Engagement: Freelance / T&M consultancy - initial 6 months, renewable (long-term engagement)

Rate: Max 400 euro per day all inclusive

Start: ASAP

Relocation: no relocation support or visa sponsorship provided

For an Agency of the United Nations, we are looking for a Fullstack .NET Developer to design, develop and maintain secure integration components and plugins within an enterprise system environment. The role focuses on enterprise-grade .NET (C#) development, system interoperability and secure data exchange with external governmental and financial intelligence systems.

Main Responsibilities:

• Analyze business and technical requirements provided by stakeholders and system architects
• Review external system interfaces (APIs, databases, XML feeds) to determine the integration approach
• Design integration solutions using .NET (C#) aligned with the system architecture
• Define the data flow between the platform and external systems, object models (POCOs) and mapping strategies, and the authentication and security approach (tokens, certificates, etc.)

Hard Skills:

• Minimum 5 years of professional experience in software development, including at least 3 years of hands-on C# (.NET) development
• Minimum 2-3 years of hands-on DevOps experience in enterprise environments
• Experience in secure software development for sensitive data environments
• Object-oriented design and POCO modelling: DTO domain model separation, layered architecture, SOLID principles and clean code; POCO-to-POCO mapping, both manual and with frameworks such as AutoMapper; schema-driven models
• HTTP-based network programming in .NET: HttpClient, HttpRequestMessage / HttpResponseMessage lifecycle, synchronous and asynchronous programming (async/await)
• Integration with RESTful APIs and SOAP services, including retry policies, timeout handling, connection resilience and proxy configuration in secure government environments
• Secure authentication in .NET: OAuth 2.0, JWT handling and validation, API key authentication, token lifecycle management, secure storage of secrets, bearer tokens on outbound requests
• Secure communication: TLS/HTTPS enforcement, certificate validation and handling
• JSON and XML serialization/deserialization, mapping between external payloads and internal POCO models, validation of structured data before transmission
• Familiarity with logging, auditing and traceability in integration systems (preferred)
• University degree (Bachelor's or equivalent) in computer science, information systems or a related field

Soft skills:

• Fluency in English is required; knowledge of another UN official language is desirable
• Ability to analyze requirements and work closely with stakeholders and system architects

The ideal candidate is an experienced C# / .NET developer with a strong background in secure system integrations, available to work onsite in Vienna.

What do we expect from you?

We expect enthusiasm and creative solutions. Active contribution to nurture the Community with research, scouting and concept of new solutions will be required.

OUR Client

Agency of the United Nations based in Vienna.

www.dropacode.com