🚀 Building a Subscription-Based Access Control System for SaaS Applications

In the world of SaaS (Software as a Service), one of the biggest challenges is controlling user access to features based on their subscription plan. Not every customer should have the same capabilities; features and usage limits must be defined clearly according to the chosen tier (Basic / Standard / Premium).

This is where a Subscription-Based Access Control System comes into play, providing a smart and scalable way to manage features and resource limits.

🎯 The Core Idea

• Each user has a subscription plan that defines which features are available.

• Usage limits are enforced (e.g., number of users, bookings, or locations).

• If a user attempts to exceed these limits or access unavailable features, an Upgrade Prompt is displayed.

✅ Key Components of the System

1. Backend Middleware

• Verifies subscription validity.

• Checks whether the requested feature is included in the plan.

• Enforces usage limits (e.g., 100 bookings in Basic plan).

• Returns meaningful error messages with upgrade suggestions.

2. Subscription Data Management

• Provides the frontend with real-time subscription data.

• Includes:

  • Plan type.

  • Available features.

  • Usage limits.

  • Current consumption.

3. Guard & Indicator Components

• Feature Guard: Blocks access to unavailable features.

• Usage Guard: Prevents new actions once limits are reached.

• Usage Indicator: Shows progress bars for usage levels.

• Feature Badge: Displays whether a feature is enabled or locked.

4. Route Protection

• All backend routes are secured to prevent bypassing restrictions.

• Rules are enforced on the server side, not just the frontend.

🏗️ System Architecture

┌─────────────────┐    ┌──────────────────┐    ┌─────────────────┐
│   Frontend      │    │    Backend       │    │   Database      │
│ FeatureGuard    │◄──►│ SubscriptionCtrl │◄──►│ Subscriptions   │
│ UsageIndicator  │    │ checkFeature()   │    │ SubscriptionPlans│
│ UpgradePrompt   │    │ checkUsageLimit()│    │ UsageTracking   │
└─────────────────┘    └──────────────────┘    └─────────────────┘

📋 Example Plans

• Basic Plan

  • 100 operations (e.g., bookings)

  • 3 sub-users

  • 1 location

• Standard Plan

  • 500 operations

  • 10 sub-users

  • 1 location

• Premium Plan

  • Unlimited everything

  • Multiple locations

  • Advanced features (analytics, custom branding, etc.)

🔒 Security Benefits

• Server-side validation prevents users from bypassing restrictions by modifying frontend code.

• Real-time usage tracking ensures accurate enforcement.

• Smooth user experience with upgrade prompts instead of generic error messages.

📌 Conclusion

A subscription-based access control system is a cornerstone of any successful SaaS application. It ensures:

• Fair distribution of features.

• Sustainable revenue through tiered plans.

• A professional user experience on par with global platforms like Shopify or HubSpot.