# Caching Strategy

> Design comprehensive multi-layer caching strategies across CDN, application, and database tiers for maximum performance.

- Skill: `atulpurohit/caching-strategy` (Agent Skill)
- Install (CLI): `npx skillmds@latest add atulpurohit/caching-strategy`
- Raw SKILL.md: https://api.skillmd.com/api/skills/atulpurohit/caching-strategy/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: AtulPurohit (https://skillmd.com/u/atulpurohit)
- Updated: 2026-09-21
- Page: https://skillmd.com/skills/atulpurohit/caching-strategy

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# Caching Strategy Designer

## Purpose
Design and implement caching at every layer to dramatically reduce latency and database load.

## Cache Layers
1. **Browser Cache**: Static assets, API responses with Cache-Control headers
2. **CDN Cache**: Cloudflare/CloudFront for global edge caching
3. **Application Cache**: Redis/Memcached for computed data
4. **Database Cache**: Query result cache, connection pooling

## Cache-Control Headers
```
# Immutable static assets (hash in filename)
Cache-Control: public, max-age=31536000, immutable

# API: cache for 60s, stale-while-revalidate for 5 min
Cache-Control: public, s-maxage=60, stale-while-revalidate=300

# Private user data
Cache-Control: private, no-cache

# Never cache
Cache-Control: no-store
```

## Application Cache Pattern
```python
# Cache-aside with stampede prevention
def get_cached(key: str, ttl: int, fetch_fn: callable):
    if value := cache.get(key):
        return value
    
    # Atomic lock prevents stampede
    with cache.lock(f"lock:{key}", timeout=10):
        # Double-check after acquiring lock
        if value := cache.get(key):
            return value
        value = fetch_fn()
        cache.set(key, value, ttl)
        return value
```

## Invalidation Strategies
- **TTL-based**: Expire after fixed time (simple, may be stale)
- **Event-driven**: Invalidate on data change (accurate, complex)
- **Tag-based**: Group related cache items, flush by tag
- **Cache-busting**: Change URL/key when content changes

## Outputs
1. Caching strategy document
2. Cache-Control header configuration
3. Application cache implementation
4. Invalidation event handlers
5. Cache monitoring metrics