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Next.js App Router principles. Server Components, data fetching, routing patterns.
name: nextjs-best-practices description: "Next.js App Router principles. Server Components, data fetching, routing patterns." risk: unknown source: community date_added: "2026-02-27"
Next.js Best Practices
Principles for Next.js App Router development.
1. Server vs Client Components
Decision Tree
Does it need...?
│
├── useState, useEffect, event handlers
│ └── Client Component ('use client')
│
├── Direct data fetching, no interactivity
│ └── Server Component (default)
│
└── Both?
└── Split: Server parent + Client child
By Default
| Type | Use | |------|-----| | Server | Data fetching, layout, static content | | Client | Forms, buttons, interactive UI |
2. Data Fetching Patterns
Fetch Strategy
| Pattern | Use | |---------|-----| | Default | Static (cached at build) | | Revalidate | ISR (time-based refresh) | | No-store | Dynamic (every request) |
Data Flow
| Source | Pattern | |--------|---------| | Database | Server Component fetch | | API | fetch with caching | | User input | Client state + server action |
3. Routing Principles
File Conventions
| File | Purpose |
|------|---------|
| page.tsx | Route UI |
| layout.tsx | Shared layout |
| loading.tsx | Loading state |
| error.tsx | Error boundary |
| not-found.tsx | 404 page |
Route Organization
| Pattern | Use |
|---------|-----|
| Route groups (name) | Organize without URL |
| Parallel routes @slot | Multiple same-level pages |
| Intercepting (.) | Modal overlays |
4. API Routes
Route Handlers
| Method | Use | |--------|-----| | GET | Read data | | POST | Create data | | PUT/PATCH | Update data | | DELETE | Remove data |
Best Practices
- Validate input with Zod
- Return proper status codes
- Handle errors gracefully
- Use Edge runtime when possible
5. Performance Principles
Image Optimization
- Use next/image component
- Set priority for above-fold
- Provide blur placeholder
- Use responsive sizes
Bundle Optimization
- Dynamic imports for heavy components
- Route-based code splitting (automatic)
- Analyze with bundle analyzer
6. Metadata
Static vs Dynamic
| Type | Use | |------|-----| | Static export | Fixed metadata | | generateMetadata | Dynamic per-route |
Essential Tags
- title (50-60 chars)
- description (150-160 chars)
- Open Graph images
- Canonical URL
7. Caching Strategy
Cache Layers
| Layer | Control | |-------|---------| | Request | fetch options | | Data | revalidate/tags | | Full route | route config |
Revalidation
| Method | Use |
|--------|-----|
| Time-based | revalidate: 60 |
| On-demand | revalidatePath/Tag |
| No cache | no-store |
8. Server Actions
Use Cases
- Form submissions
- Data mutations
- Revalidation triggers
Best Practices
- Mark with 'use server'
- Validate all inputs
- Return typed responses
- Handle errors
9. Anti-Patterns
| ❌ Don't | ✅ Do | |----------|-------| | 'use client' everywhere | Server by default | | Fetch in client components | Fetch in server | | Skip loading states | Use loading.tsx | | Ignore error boundaries | Use error.tsx | | Large client bundles | Dynamic imports |
10. Project Structure
app/
├── (marketing)/ # Route group
│ └── page.tsx
├── (dashboard)/
│ ├── layout.tsx # Dashboard layout
│ └── page.tsx
├── api/
│ └── [resource]/
│ └── route.ts
└── components/
└── ui/
Remember: Server Components are the default for a reason. Start there, add client only when needed.
When to Use
This skill is applicable to execute the workflow or actions described in the overview.
Limitations
- Use this skill only when the task clearly matches the scope described above.
- Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
- Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.