Full Stack Developer – SaaS Platform (UI/UX & Backend Security)

Remote – Worldwide excluding US

Mid-Level

Initial engagement: Approximately 1 month, with potential for ongoing work

Start Date: ASAP

Role Description

We are seeking an experienced Full Stack Developer with strong UI/UX capabilities and a solid understanding of secure SaaS architecture to help refine and prepare an existing MVP for beta testing and early customer adoption.

Our platform is a multimedia customer communication and collaboration solution designed to help customer service teams manage interactions and access information across multiple business systems, including CRM platforms such as HubSpot and Salesforce.

The core functionality has already been developed, and we are looking for a proactive, independent developer who can assess the existing application, identify architectural and security gaps, and improve the frontend experience to deliver a polished, professional, and reliable product.

The ideal candidate has experience working with early-stage SaaS products, understands multi-tenant application security, and can balance hands-on development with technical recommendations.

Our infrastructure is hosted primarily on European cloud services, including Scaleway, and we are committed to maintaining this approach rather than migrating to AWS or GCP.

This is initially a short-term engagement with the potential for additional development phases as the platform grows.

Responsibilities

• Conduct an initial technical assessment of the existing SaaS application, reviewing frontend, backend, architecture, and overall code quality.
• Identify and prioritize technical debt, security vulnerabilities, performance concerns, and opportunities for improvement.
• Enhance the frontend UI/UX to create a modern, intuitive, polished experience suitable for beta users and customer demonstrations.
• Review and improve backend architecture, ensuring appropriate data segregation, access controls, and security practices for a multi-tenant SaaS environment.
• Evaluate existing integrations, background processing, and messaging workflows for reliability and scalability.
• Work with the existing technology stack, including PostgreSQL, Temporal, message queuing services, and Scaleway infrastructure.
• Follow infrastructure-as-code and DevOps best practices, minimizing manual configuration and GUI-based infrastructure management.
• Help establish a strong technical foundation for future security and compliance requirements, including SOC 2 readiness.
• Independently manage assigned work, proactively communicate progress, and recommend practical solutions without extensive supervision.
• Collaborate directly with the founder to prioritize improvements that will have the greatest impact on product readiness.
• Provide technical recommendations on future development needs, including potential frontend/backend specialization.

Requirements

Preferred Qualifications

• 3+ years of professional full stack development experience, ideally building or maintaining SaaS applications.
• Demonstrated experience improving the UI/UX of existing web applications, with a strong understanding of modern frontend development practices.
• Solid understanding of backend architecture, API development, authentication, authorization, and secure data handling.
• Experience developing multi-tenant SaaS platforms, particularly with tenant isolation and data security.
• Proficiency with PostgreSQL and relational database design.
• Familiarity with asynchronous processing, message queues, and workflow orchestration tools such as Temporal.
• Understanding of DevOps principles, CI/CD pipelines, infrastructure as code, and automated deployments.
• Experience working with cloud-hosted applications; familiarity with Scaleway or other European cloud providers is a plus.
• Ability to review unfamiliar codebases, identify weaknesses, and independently implement improvements.
• Strong problem-solving skills and comfort working in an early-stage startup environment.
• Clear communication skills and the ability to provide actionable technical recommendations.
• Experience preparing SaaS applications for security audits or SOC 2 compliance.
• Familiarity with European cloud hosting and data sovereignty considerations.
• Experience integrating CRM platforms such as HubSpot or Salesforce.
• Background in product design or frontend engineering with a strong eye for visual quality.
• Experience with self-hosted CI/CD runners and code-driven infrastructure management.

Engagement Details

• Location: Remote, open to candidates outside the United States, with particular interest in Europe, Africa, Asia, Canada, and Latin America.
• Schedule: Flexible, with some availability for collaboration with the founder in Europe.
• Initial duration: Approximately one month, with potential extension.
• Hours: Flexible, based on project priorities and agreed budget.