Senior Full-Stack Developer – AI Property Management SaaS, Invoice Processing & PDF Billing

# Senior Full-Stack Developer – Multi-Tenant AI SaaS, Document Automation & PDF Reporting ## Project Overview We are seeking an experienced senior full-stack software developer or small development team to build a professional, scalable, AI-powered SaaS web application for managing hierarchical business records, financial documents, automated calculations, and structured reporting. The platform will initially serve a European business use case involving multiple customer organizations, managed assets, individual units, associated parties, financial documents, and periodic reporting. The application must include a secure multi-user web portal, structured data management, AI-assisted document processing, configurable calculation workflows, and professional multi-page PDF document generation. **We are not looking for a basic website, chatbot, OCR script, or simple automation prototype.** We require a maintainable, production-oriented application with a clean architecture, reliable backend, modern frontend, secure database, and comprehensive documentation. The project will be technically supervised by an experienced AI architect. We are currently evaluating potential developers, project timelines, and development costs. ## 1. Multi-Tenant SaaS Architecture The platform must support multiple independent customer organizations. Each organization will manage multiple users, hierarchical business entities, related records, documents, financial information, and reporting periods. The proposed data hierarchy is: **Platform → Customer Organization → Managed Assets → Individual Units → Associated Parties / Agreements** Examples of managed assets could include buildings, facilities, or other business entities. Each organization must have isolated data and its own users, roles, settings, and documents. ### Organization Management - Create and manage customer organizations. - Manage multiple users per organization. - Assign roles and permissions. - Maintain organization-specific settings. - Isolate all organization data. ### Managed Assets - Create, edit, archive, and search managed assets. - Maintain addresses, identifiers, descriptions, and metadata. - Support multiple individual units under each asset. - Assign responsible users. - Link documents and financial records. ### Individual Units and Associated Parties - Create and manage individual units. - Associate one or more parties with each unit. - Store agreement start and end dates. - Maintain historical associations. - Support changes over time without losing historical records. - Associate financial records with relevant entities and reporting periods. The database must support relational integrity, historical records, and future expansion. ## 2. User Authentication and Authorization The application must support secure authentication and role-based access control. Suggested roles: - Platform Administrator. - Organization Administrator. - Operational Manager. - Finance / Accounting User. - Read-Only User. Permissions must be enforced on the backend. Users must only access authorized organizations, assets, documents, and financial records. The system should support user invitations, role assignment, and secure account management. ## 3. Web Portal and Dashboards Build a responsive web application suitable for desktop and tablet use. Required modules: **A. User Management** - Login/logout. - User invitations. - Role management. - Account settings. **B. Organization Dashboard** - Overview of managed assets. - Number of individual units. - Associated records. - Uploaded documents. - Pending processing tasks. - Financial summaries. - Recent activities. **C. Asset and Record Management** - Create, edit, search, and archive records. - Manage hierarchical relationships. - View associated documents. - Manage historical information. **D. Document Management** - Upload PDF and image documents. - Bulk upload. - Secure document storage. - Document preview. - Search and filtering. - Processing status. - Review and approval workflow. **E. Financial Dashboard** - Select entity and reporting period. - View categorized financial records. - Display totals and summaries. - Identify missing or inconsistent information. - Generate reports. ## 4. AI-Assisted Document Processing The application must process financial and administrative documents using PDF extraction, OCR when required, and AI-assisted structured data extraction. ### Required Capabilities - Extract supplier or issuer information. - Extract document identifiers. - Extract dates and relevant periods. - Extract amounts, tax values, and currencies. - Identify descriptions and relevant references. - Suggest appropriate categories. - Associate documents with relevant business entities. - Validate extracted information. ### AI Classification The application should support configurable categories and business-specific classification rules. AI results must be presented as suggestions that users can review and correct. ### Validation and Human Review - Detect possible duplicates. - Identify missing information. - Highlight inconsistent amounts. - Flag uncertain classifications. - Allow manual correction. - Support approval/rejection workflows. - Maintain audit logs. Financial calculations must use deterministic, testable backend logic rather than relying on LLM arithmetic. ## 5. Configurable Financial Processing The platform must support periodic financial calculations based on approved data. Required features: - Define reporting periods. - Group financial documents by entity and category. - Calculate category totals. - Support configurable allocation and calculation rules. - Handle reviewed splits across entities or periods. - Maintain references to underlying documents. - Identify missing or unapproved records. - Store approved calculation snapshots. - Export financial data to Excel/CSV. The calculation engine should be modular and extensible. Complex industry-specific calculation rules will be provided during a later requirements phase and must be estimated separately if they exceed the agreed MVP scope. ## 6. Mandatory Multi-Page PDF Document Generation **This is a core requirement.** The platform must generate professionally formatted, multi-page PDF documents using predefined templates and structured financial data. Simple single-page PDF summaries are not sufficient. ### Required Features - Generate reports for individual assets, units, and associated parties. - Support multiple pages per document. - Follow predefined layouts and formatting specifications. - Include dynamic tables and financial breakdowns. - Display calculated totals and supporting details. - Include logos, addresses, headers, footers, and page numbers. - Handle automatic page breaks. - Continue tables correctly across pages. - Support German date, currency, and number formatting. - Generate documents from approved financial records. - Support preview and download. - Support batch PDF generation. - Allow ZIP downloads of generated documents. - Retain document-generation history. ### Template Requirements The system must support reusable templates. Templates, financial calculations, data access, and PDF rendering must be implemented as separate components. We will provide representative document layouts to shortlisted developers during the requirements phase, subject to appropriate confidentiality arrangements. The developer should recommend a reliable server-side PDF generation approach. ### Quality Requirements - Consistent formatting. - Correct page numbering. - No overlapping or truncated content. - Reliable rendering of long tables. - Reproducible calculations and output. - Accurate handling of multi-page documents. Please estimate this module separately. ## 7. Data Import and Export Required capabilities: - CSV/Excel import of hierarchical business records. - CSV/Excel import of associated parties and agreements. - Bulk document uploads. - Excel/CSV financial exports. - PDF document generation. - Download of original documents. The architecture should allow future integrations with external business software through APIs. Specific third-party integrations are not required for the initial MVP. ## 8. Preferred Technology Stack **Frontend** - React / Next.js. - TypeScript. - Modern UI component library. **Backend** - Python FastAPI. - REST APIs. - Modular architecture. **Database** - PostgreSQL. - SQLAlchemy or equivalent. - Database migrations. - Secure tenant isolation. **AI Processing** - PDF extraction. - OCR fallback. - LLM-based structured extraction. - Schema validation. - Configurable AI provider. **Background Processing** - Redis/Celery or equivalent. - Asynchronous document processing. - Batch report generation. - Job tracking. **Document Storage** - S3-compatible storage. - Secure access controls. **PDF Generation** - HTML/CSS-to-PDF, WeasyPrint, Playwright, or equivalent. - Reusable document templates. **Deployment** - Docker. - CI/CD. - Secure configuration. - EU-based hosting preferred. Alternative technologies are acceptable with technical justification. A modular monolith is preferred for the initial release. ## 9. Security and Data Protection The application will handle business, personal, and financial information. Required engineering controls: - Secure authentication. - Role-based authorization. - Organization-level data isolation. - HTTPS. - Secure document storage. - Audit logging. - Backup and recovery. - Data retention and deletion mechanisms. - Secure secret management. - Protection against common web vulnerabilities. - Controls for third-party AI data processing. The system should be designed to support applicable European data-protection requirements. ## 10. Testing and Documentation Required deliverables: - Complete source code. - Frontend and backend. - Database schema and migrations. - Automated tests for critical functionality. - Tests for tenant isolation. - Tests for financial calculations. - Tests for document extraction. - Tests for PDF generation. - Deployment instructions. - API documentation. - Architecture documentation. - Developer setup guide. The application must be maintainable by another qualified developer. ## 11. Proposed Development Milestones Please provide separate estimates for: **Milestone 1: Requirements and Architecture** - Requirements clarification. - Data model. - System architecture. - Wireframes. - Development setup. **Milestone 2: Core Multi-Tenant SaaS Portal** - Authentication. - Organizations and users. - Hierarchical asset management. - Associated parties and agreements. - Dashboards. **Milestone 3: AI Document Processing** - Upload and storage. - PDF/OCR extraction. - AI structured extraction. - Classification. - Human review. **Milestone 4: Financial Processing** - Reporting periods. - Category management. - Calculations and validation. - Exports. **Milestone 5: Multi-Page PDF Reporting** - Template system. - Structured reports. - Multi-page financial tables. - Batch generation. - PDF testing. **Milestone 6: Testing, Deployment and Handover** - Integration testing. - Security checks. - Bug fixes. - Deployment. - Documentation. - Source-code handover. ## 12. Future Expansion The architecture should support future development of: - Industry-specific calculation modules. - External software integrations. - Advanced analytics. - Additional AI automation workflows. - Customer self-service portals. - Subscription billing. - Multilingual interfaces. - Mobile applications. These features are not part of the initial MVP unless separately agreed. ## 13. Confidentiality and Intellectual Property This project is currently in the technical evaluation and planning stage. Additional business-specific requirements, representative documents, and detailed workflows may be shared with shortlisted candidates subject to appropriate confidentiality arrangements. Any engagement will require a separately agreed contract covering scope, milestones, payment, confidentiality, deliverables, and intellectual-property rights. Pre-existing code and third-party components must be disclosed with their applicable licenses. No development work is authorized before the relevant contractual arrangements and project milestone are approved. ## 14. Required Proposal Information Please provide: 1. Examples of multi-tenant SaaS applications you have developed. 2. Experience with AI document extraction and automation. 3. Experience with complex, multi-page PDF generation. 4. Proposed technical architecture. 5. Estimated total development hours. 6. Estimated timeline in calendar weeks. 7. Hourly rate. 8. Estimated fixed-price project cost. 9. Milestone-by-milestone cost breakdown. 10. Separate cost estimate for the PDF reporting engine. 11. Major assumptions and exclusions. 12. Expected infrastructure and AI API costs. 13. Your availability and earliest possible start date. Please provide realistic estimates rather than artificially low quotations. We prioritize software quality, maintainability, security, technical competence, and clear communication. We are interested in potential long-term collaboration. **Please begin your proposal with “Multi-Tenant AI SaaS” to confirm that you have reviewed the requirements.** This posting is a request for proposals only and does not constitute a commitment to award a contract or proceed with development.