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Case Study

Catalyst PSA Platform

Overview

Catalyst is a comprehensive Professional Services Automation (PSA) platform designed to streamline project management, resource allocation, time tracking, and financial management for professional services organizations. This enterprise-grade SaaS application represents a modern approach to PSA software, built with scalability, maintainability, and user experience as core priorities.

Project Scale

  • Architecture Patterns: 61 identified patterns
  • Development Period: 2023-2024
  • Team Size: 5-8 developers

Technical Architecture

Hexagonal Architecture

The platform is built using Hexagonal Architecture (Ports and Adapters pattern), which provides exceptional separation of concerns and makes the codebase highly testable and maintainable. This architectural approach allows us to:

  • Isolate business logic from external dependencies
  • Easily swap out infrastructure components
  • Write comprehensive unit tests without external dependencies
  • Maintain clear boundaries between different layers of the application

CQRS Pattern

We implemented Command Query Responsibility Segregation (CQRS) to optimize read and write operations separately. This pattern enables:

  • Write Side: Handles commands that modify state, ensuring data consistency and business rule enforcement
  • Read Side: Optimized queries for reporting and data display
  • Scalability: Independent scaling of read and write operations
  • Performance: Tailored data models for different use cases

Domain-Driven Design

The application follows DDD principles with well-defined bounded contexts:

  • Project Management Context: Handles project lifecycle, milestones, and deliverables
  • Resource Management Context: Manages team allocation and capacity planning
  • Time Tracking Context: Captures and processes time entries
  • Financial Context: Handles billing, invoicing, and revenue recognition
  • Client Management Context: Manages client relationships and contracts

Multi-Tenant Architecture

Built from the ground up as a multi-tenant SaaS platform with:

  • Data Isolation: Complete separation of tenant data at the database level
  • Tenant Context: Automatic tenant resolution from authentication token
  • Shared Infrastructure: Efficient resource utilization across tenants
  • Customization: Per-tenant configuration and feature flags

Technology Stack

Backend

  • NestJS: Enterprise-grade Node.js framework providing excellent structure and TypeScript support
  • TypeScript: Strong typing throughout the application
  • PostgreSQL: Reliable, performant relational database
  • Prisma: Type-safe database client with excellent migration support
  • Drizzle ORM: Additional ORM used for complex queries and performance optimization

Frontend

  • React: Component-based UI development
  • Next.js: Server-side rendering and optimal performance
  • TypeScript: Type safety on the frontend
  • Tailwind CSS: Utility-first CSS framework for rapid UI development

Infrastructure

  • Docker: Containerization for consistent environments
  • Kubernetes: Container orchestration for production deployment
  • PostgreSQL: Primary database with replication for high availability
  • Redis: Caching layer and session management

Key Features

Project Management

  • Comprehensive project tracking with customizable workflows
  • Milestone and deliverable management
  • Project templates for common engagement types
  • Real-time project status dashboards
  • Resource forecasting and capacity planning

Time Tracking

  • Intuitive time entry interface
  • Mobile-friendly time capture
  • Bulk time entry for efficiency
  • Approval workflows
  • Integration with calendar systems

Resource Management

  • Visual resource allocation
  • Skill-based resource matching
  • Capacity planning tools
  • Utilization reporting
  • Bench management

Financial Management

  • Flexible billing models (fixed fee, time & materials, retainer)
  • Automated invoicing
  • Revenue recognition
  • Expense tracking and reimbursement
  • Financial forecasting and reporting

Reporting & Analytics

  • Real-time dashboards
  • Customizable reports
  • Export to Excel, PDF
  • Scheduled report delivery
  • KPI tracking and visualization

Development Practices

Testing Strategy

  • Unit Tests: Comprehensive coverage of business logic
  • Integration Tests: Testing interactions between components
  • E2E Tests: Critical user journey validation
  • Test Coverage: 85%+ coverage maintained

CI/CD Pipeline

  • Automated testing on every commit
  • Staging environment for QA validation
  • Blue-green deployment strategy
  • Automated database migrations
  • Rollback capabilities

Code Quality

  • ESLint and Prettier for code consistency
  • SonarQube for code quality metrics
  • Regular code reviews
  • Architectural decision records (ADRs)

Challenges Overcome

Performance Optimization

  • Implemented database query optimization reducing response times by 60%
  • Added intelligent caching strategy
  • Optimized N+1 query problems
  • Database indexing strategy

Data Migration

  • Migrated from legacy system with 5+ years of historical data
  • Zero-downtime migration strategy
  • Data validation and reconciliation
  • Rollback procedures

Scalability

  • Designed for horizontal scaling
  • Database sharding strategy for large tenants
  • Connection pooling optimization
  • Background job processing with Bull

Business Impact

  • 30% Reduction in project overhead costs
  • 40% Improvement in resource utilization
  • 50% Faster invoice generation
  • 99.9% Uptime SLA achieved
  • 15+ Enterprise Clients onboarded in first year

Lessons Learned

  1. Architecture Matters: The upfront investment in Hexagonal Architecture paid dividends in maintainability
  2. Type Safety: TypeScript end-to-end eliminated entire classes of bugs
  3. Testing: Comprehensive test suite enabled confident refactoring
  4. Documentation: Architectural Decision Records (ADRs) proved invaluable for team alignment
  5. Incremental Migration: Phased approach to CQRS implementation reduced risk

Future Enhancements

  • AI-powered resource recommendations
  • Advanced forecasting with machine learning
  • Mobile native applications
  • Integration marketplace
  • Workflow automation engine

This project demonstrates the ability to architect and deliver enterprise-grade SaaS applications with modern technology stacks, solid architectural foundations, and a focus on scalability and maintainability.