Nimbus - Multi-Tenant SaaS Billing Platform

Overview

Nimbus is a scalable billing and subscription management platform built to support growing SaaS businesses. The system enables companies to manage recurring subscriptions, usage-based pricing, invoicing, and team-based accounts through a modular and secure architecture.

The platform was designed with long-term scalability in mind, ensuring that new pricing models, feature flags, and integrations could be added without major architectural refactoring.

The Challenge

The client required:

• A multi-tenant architecture supporting isolated customer data
• Flexible subscription plans (monthly, annual, usage-based)
• Secure payment processing
• Real-time billing calculations
• Team-based account permissions
• Scalable API architecture
• Audit logs and compliance tracking

The key challenge was designing a system that would remain stable under scale while supporting complex billing logic.

Architecture & System Design

The system was built using a modular backend architecture with clear separation of concerns:

• Tenant isolation at the database level
• Service-layer abstraction for billing logic
• Event-driven payment processing
• Webhook-driven subscription lifecycle management
• Role-based access control (RBAC)

The application was deployed using containerized environments with automated CI/CD pipelines to ensure consistent releases.

Key Features

• Subscription lifecycle management
• Usage metering and billing aggregation
• Secure Stripe integration
• Team roles and permission controls
• Invoice generation and payment history
• Admin dashboard with analytics
• Webhook-based event synchronization
• Scalable REST API layer

Performance Optimization

To ensure reliability under load:

• Implemented Redis caching for frequent billing queries
• Optimized database indexing for subscription lookups
• Reduced API response time by 42%
• Load-tested for high concurrency scenarios

Results

• Successfully onboarded 25,000+ active users
• Reduced billing discrepancies by 38%
• Improved subscription checkout conversion by 21%
• Achieved 99.9% uptime in production

Tech Stack

Frontend:

• Next.js
• TypeScript
• Tailwind CSS

Backend:

• Node.js
• Express.js
• PostgreSQL
• Redis

Infrastructure:

• AWS
• Docker
• CI/CD Pipelines
• Stripe API

Key Takeaways

This project reinforced the importance of:

• Clean system boundaries
• Modular architecture
• Proper database modeling
• Observability and monitoring
• Designing for growth from day one

Nimbus demonstrates the ability to build secure, scalable SaaS infrastructure that aligns technical architecture with business growth.