API Developer & Gateway Administrator

Location: Brussels, Belgium (Hybrid: 2-3 days remote per week)

Type: Freelance Contract

Experience Level: Senior / Expert (10+ years of experience)

Languages: French or Dutch (Professional working proficiency, min. 3/4) OR English (Professional working proficiency, min. 3/4)

About Smile 🌟

Passionate about tech, digital, and innovation? Join the 1,800 employees at Smile, the European leader in open-source integration, spread across 20 agencies in 9 countries.

Collaborative spirit and knowledge sharing are at the heart of our DNA. Our experts push the boundaries of open source every day to build a smarter, more efficient, and more responsible digital world. Here, we don't just follow trends, we create them! Join Smile in Brussels and take part in projects that truly matter! 🏆

The Opportunity

On behalf of our client—a major player in their sector based in Brussels—we are looking for an outstanding Senior API Developer & Gateway Administrator on a freelance basis.

In this role, you will act as a key technical expert, driving the development, configuration, and secure deployment of critical API gateways. You will play a vital role in building modern, scalable, and highly secure integration architectures in a collaborative, Agile environment.

Your Responsibilities

• API Gateway Development & Configuration: Design, build, and deploy secure API Gateways, specializing in Axway (or equivalent enterprise suites like Apigee/WSO2).

• API Design: Define and implement robust OpenAPI specifications, promoting modern SOA/REST architectural patterns.

• API Security & Identity: Implement and enforce industry-standard security protocols, including OAuth2, JWT, PKI, and secure web services.

• Vulnerability & Testing: Proactively manage API security posture utilizing tools like Snyk and conduct comprehensive web service testing.

• Modern Lifecycle & Automation: Integrate your developments within public cloud infrastructures and CI/CD pipelines, utilizing Git for version control.

• Agile Collaboration: Participate actively in Agile ceremonies, using Jira and Confluence for progress tracking and high-quality technical documentation.

Your Profile

• Experience: Senior profile with 10+ years of hands-on experience in IT integration, with a strong focus on API gateway development and security.

• Core Technical Expertise:

  • Solid experience with API Gateway platforms (specifically Axway, or alternatively Apigee or WSO2).

  • Mastery of API standards, SOA/REST architecture, and data formats (XML/JSON).

  • Strong command of API security frameworks and tools (JWT, OAuth2, PKI, Snyk).

  • Hands-on experience with Public Cloud environments, CI/CD automation pipelines, and Git.

  • Experience in automated web services testing.

• Methodology: Proven experience working within an Agile framework utilizing Jira and Confluence.

• Languages: Professional working proficiency (3/4) in either Dutch, French, or English.

Why Smile? 😊

• Proximity Management: Our proximity management by peers fosters dialogue and the implementation of a tailored career path.

• Continuous Growth: Because the digital sector is in constant motion, Smile is committed to making you an expert in your field, thanks to a comprehensive training offer: access to an e-learning platform, financing of certifications, and dedicated knowledge-sharing tools.

• Vibrant Community: Your year will be animated by group and agency events: annual convention, participation in trade fairs, summer party, and both formal & informal afterworks.

The Next Steps 🚀

1. First Contact: A phone call to discuss your aspirations and what we can offer you.

2. Meeting: An opportunity to get to know each other and explore your professional background.

3. Business Interview: A discussion with one of our experts to assess your skills and define your goals.