full-stack developer in SaaS platforms

For the technical completion and further development of a new SaaS platform, we are looking for an experienced and pragmatic freelance Full-stack Developer (self-employed). This is an in-house developed custom CRM, planning and student tracking system for homework institutes and educational organizations. The core functionalities and payment integrations are in place, but before we roll out the platform more widely to external organizations, the final crucial steps need to be completed.

• Build multi-tenancy: adapt the application and database architecture to support multiple external educational organizations. Because the system handles sensitive student data, data and file separation between organizations must be completely watertight (compliant with GDPR).
• Fix a number of small, clearly defined bugs in both the front end and back end so the system is ready to go live without issues.

• A self-employed contractor based in the Netherlands (in connection with an NDA, data processing agreement, and the preference to hold the kick-off in person in Amsterdam).
• In-depth knowledge of Plain PHP and SQL, with a strong focus on data security (such as prepared statements, session management, and strict data isolation without relying on heavy frameworks).
• Demonstrable experience setting up secure, scalable SaaS and multi-tenant structures.
• Someone who writes clean, maintainable code and proactively contributes ideas on the best technical approach.

• Direct communication and short lines of communication with the founder.
• We start with a clearly scoped, paid trial milestone (fixing the outstanding bugs) to see whether the collaboration is a good fit. After that, we immediately take on the multi-tenancy architecture.
• Flexible, hybrid working arrangement: mostly remote work, with an on-site kick-off in Amsterdam.