Senior Bubble.io Developer – SaaS Platform, Microsoft 365 & API Integrations

Contract / Fixed-Project Engagement | Remote We are seeking an experienced Senior Bubble.io Developer to design, develop, integrate, test and deliver a new multi-user SaaS web application. This is not a simple website, marketplace or prototype build. The successful developer will be responsible for developing a structured, production-ready Bubble application involving user and account management, document-management functionality, workflows, Microsoft 365 integration, API communication, file processing and secure cloud-based document storage. Detailed project specifications and Principal Project Requirements will be provided to shortlisted candidates progressing to the second-stage interview. The Role The Developer will take technical responsibility for the design and implementation of the application in accordance with an established functional requirements specification. The engagement will include Bubble application architecture, database design, workflow development, responsive interface development, API integration, Microsoft 365/SharePoint integration, document-processing workflows, security and permissions, testing, deployment and technical handover. The Developer will work directly with the Project Director and participate in a weekly online progress meeting to demonstrate development progress, identify technical issues and confirm upcoming priorities. Essential Technical Experience Candidates must demonstrate strong commercial experience with Bubble.io and be capable of independently architecting and delivering complex production applications. Strong proficiency is required in: Advanced Bubble.io application architecture and development Bubble database design, data relationships and scalable data structures Backend workflows, scheduled workflows and complex workflow logic Bubble privacy rules, authentication, role-based permissions and secure multi-user applications Multi-tenant SaaS architecture and secure customer/account data separation Responsive application design across desktop, tablet and mobile Bubble API Connector and integration with REST APIs JSON, API requests/responses, authentication headers, tokens and error handling OAuth 2.0 and secure external-service authentication Microsoft Graph API Microsoft 365 and SharePoint Online integration Programmatic file upload, retrieval, update, download, rename, deletion and sharing Secure management of API credentials, application secrets and authentication tokens File metadata management and synchronisation between Bubble and external repositories Robust transaction handling, failure management and data integrity Search, filtering, document registers and structured record-management functionality Production deployment, performance optimisation and application security Document Automation & File Processing The application includes document-generation and document-management functionality. Candidates should have demonstrable experience with, or a strong technical understanding of: Automated generation and processing of Microsoft Word and Excel files Programmatic placeholder or field replacement within document templates Preservation of document formatting, tables, formulas, page layouts and other document features during automated processing File creation and manipulation through APIs, backend services or approved server-side processing Microsoft Office file formats and document-processing workflows Maintaining reliable associations between application database records and externally stored files Experience working with Microsoft Project (.mpp) files or other complex Microsoft document formats will be highly regarded. The successful candidate must be capable of identifying where functionality should be implemented directly within Bubble and where an external API, custom code, server-side function or other approved technical service is more appropriate. Microsoft Integration Strong Microsoft integration experience is particularly desirable. Applicants with previous experience configuring and working with the following will be strongly preferred: Microsoft Graph API | SharePoint Online | Microsoft Entra ID / Azure authentication | OAuth 2.0 | Microsoft 365 file services | Microsoft document editing and sharing workflows The Developer should understand permission scopes, application authentication, secure token management and the principles of least-privilege access. Development Standards The successful Developer will be expected to: Develop the application using a clean, logical and maintainable architecture that can be expanded without unnecessary redevelopment. Use appropriately structured Bubble data types, workflows, reusable elements and backend processes rather than unnecessarily complex or duplicated logic. Implement suitable security controls and maintain strict separation between individual customer accounts, users and project information. Design integrations with appropriate error handling, retry behaviour and transaction controls so failed external operations do not leave incomplete or misleading records. Identify technical limitations or risks early and recommend suitable solutions before implementing material departures from the approved requirements. Avoid introducing unnecessary plugins, third-party services or ongoing software dependencies. Progressively test functionality throughout development, including integration, permissions, data separation, responsive behaviour and end-to-end workflows. Provide clear technical documentation and complete handover of application administration, workflows, integrations, configurations, custom code and other project-specific development assets at completion. Candidate Requirements We are looking for a developer who is technically strong, commercially experienced and capable of taking ownership of a complex application build. Applicants should be able to demonstrate previous production Bubble applications involving significant backend logic and API integrations rather than predominantly front-end or template-based Bubble projects. The successful candidate must have strong problem-solving skills, communicate technical matters clearly to a non-software-development project team, raise potential technical constraints proactively and be comfortable working in accordance with a detailed written requirements specification and milestone-based acceptance process. Bubble Developer Certification is highly regarded but will not replace demonstrated experience delivering technically comparable applications. Application Requirements To be considered, please provide: 1. A brief summary of your Bubble.io development experience. 2. Examples of two or three production Bubble applications you have personally developed. 3. A description of the most technically complex Bubble application you have delivered and your personal responsibilities on that project. 4. Details of any Microsoft Graph API, SharePoint Online or Microsoft 365 integration experience. 5. Details of any automated Word, Excel or other document-generation experience. 6. An explanation of your experience developing multi-tenant SaaS applications and implementing customer data separation. 7. Your location and usual working hours/time zone. Shortlisted applicants will be invited to a first-stage technical interview. Candidates selected to progress further will be provided with detailed project requirements and invited to participate in a more detailed technical and commercial review. Please do not apply if your Bubble experience is predominantly limited to basic websites, landing pages, simple marketplaces or template customisation. We are specifically seeking an experienced application developer capable of delivering complex integrations and production SaaS architecture.