Senior Backend Engineer

Company Description
Colliers is a leading diversified professional services and investment management company. With operations in 68 countries, our 22,000 enterprising people work collaboratively to provide expert advice to maximize the potential of property and real assets to accelerate the success of our clients, our investors and our people.

We are at the forefront of the real estate industry, leading the way and backed by an exceptional record of success. We are building for our future –
and yours.
We strive to build our business at a competitive pace by augmenting internal growth with smart strategic acquisitions that increase market share, expand service offerings and extend our geographic reach for the benefit of our clients and shareholders.

For more than 29 years, Colliers has created value for shareholders that has resulted in superior returns and industry growth. Our people also own significant equity in our business, which brings pride of ownership to everything we do. We are passionate, take personal responsibility and always do what's right for our clients, people and communities.

Job Description
We are seeking an experienced and passionate
Senior Backend Engineer
for our
newly established Technology Hub
in Madrid. This is a unique opportunity to become part of the founding team that helps shape the culture, practices, and technical direction. Working in a
hybrid model
(remote & onsite), you will enjoy significant freedom to
innovate and influence
the future of one of the world's largest commercial real estate companies. With the leadership of the Global Technology Hub coming from a background of technology startups, you will benefit from a fast-paced learning environment, high visibility of your contributions and opportunities to shape processes, culture and technology strategies. At the same time, you take advantage of the stability, resources, and reach of a
successful global company
.

Guided by our global digital strategy, the Madrid Hub collaborates closely with international teams to deliver
world-class technology solutions
that power the future of commercial real estate.

As
Senior Backend Engineer
, you specialize in .Net, and will play a key role in designing, developing and maintaining scalable, secure, and high-performance enterprise software solutions. You will contribute to global products and platforms that serve both internal and external customers in Commercial Real Estate across multiple regions. Working closely with international Product, Engineering, DevOps, Data, QA and Architecture teams, you will ensure delivery excellence, software quality and great customer experience.

You are a hands-on problem-solver with strong software design principles, who thrives in a collaborative and agile environment. This role offers the opportunity to influence technical direction and mentor junior engineers while building solutions with real business impact. You will work within the Global Technology Department from our Madrid office (two days a week).

Software Development and Design

• Implement scalable and maintainable B2B software products using the Microsoft .NET stack (C#, ASP.NET Core).
• Contribute to architecture discussions/technology evaluation and participate in system and code reviews.
• Help define and adhere to coding standards, documentation and modern software lifecycle best practices, such as SOLID principles, unit testing, CI/CD, and secure coding.
• Collaborate with product managers, designers, and QA to translate business requirements into technical specifications and user stories.
• Participate in sprint planning, backlog refinement and feature grooming to ensure technical feasibility and shared understanding across disciplines.

Technical Leadership

• Act as a technical mentor to mid-level and junior engineers within your team or project and beyond.
• Identify opportunities for technical improvements and advocate for high-quality engineering standards.
• Participate in design and code review sessions to uphold engineering excellence across the team.
• Take on technical ownership of production systems.
• Continuous improvement of agile methodologies and tools.

Quality and Performance

• Drive culture of test-first development with unit, integration and performance testing
• Support root cause analysis and resolution of production issues, ensuring high reliability and uptime.
• Contribute to ongoing platform refactoring and modernization efforts.

Global Collaboration

• Work closely with DevOps and Engineering Operations teams to optimize build pipelines, observability and deployment automation.
• Ensure compliance with global standards, information security policies and regulatory requirements.
• Collaborate regularly with Product Teams, especially Product Owners, to align on requirements, clarify priorities and deliver business value iteratively.

Qualifications
Required Skills/Experience:

• 5+ years of experience in .NET software development with C# and ASP.NET Core.
• Strong knowledge of object-oriented design, microservices architecture and API development (REST/GraphQL).
• Experience with SQL and NOSQL databases (e.g. SQL Server or Postgres SQL, Cosmos DB, MongoDB), as well as caching with Redis or similar.
• Advanced understanding of cloud-native architectures, CI/CD pipelines and DevOps practices (preferably GCP).
• Experience in containerization (Docker, Kubernetes).
• Agile Development experience (Scrum/Kanban), including story estimation, code reviews and pair programming.
• Experience working in distributed or remote teams and using tools such as Jira, GitHub, Miro and Azure DevOps.
• Solid understanding of performance optimization.
• Excellent interpersonal and communication skills, fluent in English and Spanish.
• Passionate about building high-quality software products with empowered teams.
• Understanding of secure development practices and compliance frameworks (e.g. ISO27001, GDPR, SOC2).

Preferred Skills/Experience

• Experience in working in a global, multi-cultural organization.
• Exposure to domain-driven design (DDD) and event-driven architecture.
• Experience with observability tools (e.g. Sentry, Lighthouse etc.)
• Ability to work in a fast-paced, growing tech environment and to foster change in larger organizations.