Seifeddine Bejaoui

Building Scalable Frontend Architecture for B2B SaaS: Lessons from 10+ Years of Engineering

After a decade of building and scaling frontend applications for startups, scale-ups, and enterprise organizations, I've learned that frontend architecture isn't just about writing code—it's about creating systems that can grow, adapt, and maintain performance as your product scales.

In this article, I'll share the architectural patterns, strategies, and hard-won lessons from my experience as a Lead Frontend Engineer at Prediko, where I led the frontend team on a B2B SaaS platform used by fast-growing e-commerce brands. I'll also draw insights from my work on enterprise-grade platforms, including a long-term Airbus mission where reliability and performance were non-negotiable.

Why Frontend Architecture Matters in B2B SaaS

When I joined Prediko, the frontend codebase had been delivered by an external agency. While it worked, it was fragile—small changes would break in unexpected ways, onboarding new developers was painful, and scaling features felt like walking on eggshells.

The problem wasn't the technology stack (React, TypeScript, Next.js are solid choices). The problem was the lack of architectural foundation.

In B2B SaaS applications, you're not just building features—you're building a platform that needs to:

  • Handle complex business logic while remaining maintainable
  • Scale with your user base without performance degradation
  • Support rapid feature development without technical debt accumulation
  • Enable team collaboration with clear patterns and conventions
  • Maintain reliability under high-stakes enterprise environments

The Foundation: Component Architecture and Code Organization

1. Domain-Driven Folder Structure

Instead of organizing by file type (components/, utils/, hooks/), I organize by domain or feature:

src/
  features/
    inventory/
      components/
      hooks/
      services/
      types/
    orders/
      components/
      hooks/
      services/
      types/
  shared/
    components/
    hooks/
    utils/
    types/

Why this works: When you need to modify inventory-related features, everything is in one place. New team members can understand the codebase faster, and you reduce the cognitive load of navigating scattered files.

2. TypeScript-First Development

TypeScript isn't optional in scalable frontend architecture. It's your safety net.

// Instead of this:
function processOrder(order) {
  return order.items.map(item => item.price * item.quantity)
}

// Do this:
interface OrderItem {
  price: number
  quantity: number
  sku: string
}

interface Order {
  id: string
  items: OrderItem[]
  status: 'pending' | 'processing' | 'completed'
}

function processOrder(order: Order): number {
  return order.items.reduce(
    (total, item) => total + item.price * item.quantity,
    0
  )
}

The benefits I've seen:

  • Catch errors at compile time, not in production
  • Self-documenting code through types
  • Better IDE autocomplete and refactoring
  • Easier onboarding for new developers

3. Custom Hooks for Business Logic

Extract complex business logic into custom hooks. This keeps components focused on presentation:

// hooks/useInventoryManagement.ts
export function useInventoryManagement(productId: string) {
  const [inventory, setInventory] = useState<Inventory | null>(null)
  const [loading, setLoading] = useState(true)
  const [error, setError] = useState<Error | null>(null)

  useEffect(() => {
    fetchInventory(productId)
      .then(setInventory)
      .catch(setError)
      .finally(() => setLoading(false))
  }, [productId])

  const updateStock = useCallback(async (quantity: number) => {
    // Business logic here
  }, [productId])

  return { inventory, loading, error, updateStock }
}

This pattern makes business logic testable, reusable, and easier to reason about.

State Management: When to Use What

After working with various state management solutions, here's my pragmatic approach:

Local Component State (useState, useReducer)

Use for UI-only state that doesn't need to be shared:

  • Form inputs
  • Modal open/close
  • UI toggles

Context API

Use for truly global state that rarely changes:

  • User authentication
  • Theme preferences
  • Feature flags

Server State (React Query, SWR)

Use for data fetched from APIs:

  • Product listings
  • User data
  • Real-time updates

The mistake I see most often: Using Redux or Context for everything. Most state should live close to where it's used, and server state should be managed by a library designed for it.

Performance Optimization Strategies

1. Code Splitting and Lazy Loading

In Next.js, leverage automatic code splitting:

// Lazy load heavy components
const InventoryDashboard = dynamic(() => import('./InventoryDashboard'), {
  loading: () => <DashboardSkeleton />,
  ssr: false, // If it's client-only
})

2. Memoization Strategy

Don't over-memoize. Use useMemo and useCallback strategically:

// ✅ Good: Expensive computation
const sortedProducts = useMemo(
  () => products.sort((a, b) => a.name.localeCompare(b.name)),
  [products]
)

// ❌ Unnecessary: Simple operations
const fullName = useMemo(() => `${firstName} ${lastName}`, [firstName, lastName])

3. Virtual Scrolling for Large Lists

When dealing with thousands of items (common in B2B SaaS dashboards), use virtual scrolling:

import { useVirtualizer } from '@tanstack/react-virtual'

function ProductList({ products }) {
  const parentRef = useRef()
  const virtualizer = useVirtualizer({
    count: products.length,
    getScrollElement: () => parentRef.current,
    estimateSize: () => 50,
  })

  return (
    <div ref={parentRef} style={{ height: '600px', overflow: 'auto' }}>
      <div style={{ height: `${virtualizer.getTotalSize()}px` }}>
        {virtualizer.getVirtualItems().map((virtualItem) => (
          <ProductRow
            key={virtualItem.key}
            product={products[virtualItem.index]}
          />
        ))}
      </div>
    </div>
  )
}

Testing Strategy

Testing frontend architecture requires a layered approach:

  1. Unit tests for business logic (hooks, utilities)
  2. Component tests for UI behavior
  3. Integration tests for critical user flows
  4. E2E tests for high-value paths

Focus your testing effort where it matters most—business-critical features and complex logic.

CI/CD and Quality Gates

At Prediko, we implemented:

  • Type checking in CI (TypeScript strict mode)
  • Linting with ESLint (prevents common mistakes)
  • Automated testing before deployment
  • Performance budgets (prevent regressions)
  • Visual regression testing for critical UI

These gates catch issues before they reach production, saving hours of debugging.

Lessons from Enterprise Environments

Working on the Airbus mission taught me that reliability is a feature. In enterprise contexts:

  • Error boundaries are essential—one component failure shouldn't crash the app
  • Graceful degradation ensures core functionality works even if features fail
  • Comprehensive logging helps diagnose issues in production
  • Performance monitoring catches regressions early

The Architecture Review Process

When I joined Prediko, I established a lightweight architecture review process:

  1. New feature proposals get reviewed for architectural fit
  2. Major refactors require a brief design document
  3. Pattern decisions are documented and shared

This doesn't slow down development—it prevents costly mistakes and ensures consistency.

Conclusion: Building for the Long Term

Scalable frontend architecture isn't about using the latest framework or the most complex patterns. It's about:

  • Making intentional decisions based on your team size and product needs
  • Prioritizing maintainability over clever solutions
  • Establishing patterns that your team can follow consistently
  • Investing in tooling that catches errors early
  • Documenting decisions so future you (and your team) understand the "why"

The frontend architecture I helped build at Prediko didn't just stabilize the codebase—it enabled the team to ship features faster, onboard developers more easily, and scale the platform as the business grew.

If you're facing similar challenges with a fragile frontend codebase, remember: every large, maintainable codebase started small. The key is making the right architectural decisions early and being willing to refactor as you learn.

Want to discuss frontend architecture for your B2B SaaS application? I'm always open to connecting with fellow engineers facing similar challenges.