claude-skills-supercharged: Skill for Claude Code

API Security Best Practices

Purpose

This guardrail skill enforces critical security practices when building APIs. It helps prevent common vulnerabilities including OWASP Top 10 threats, ensuring your API is secure by design.

When to Use This Skill

Auto-activates when:

• Working with API endpoints or routes
• Mentions of "api", "endpoint", "authentication", "authorization"
• Adding request handlers or middleware
• Working with user input or database queries

Authentication & Authorization

Always Require Authentication

Every API endpoint must have explicit authentication:

# Good - Authentication required
@app.post("/api/users")
@require_auth  # Explicit authentication decorator
async def create_user(request: Request):
    user = get_current_user(request)
    # Implementation

// Good - Authentication middleware
router.post('/api/users', authenticate, async (req, res) => {
  const user = req.user; // Set by authenticate middleware
  // Implementation
});

Never skip authentication:

# BAD - No authentication!
@app.post("/api/users")
async def create_user(request: Request):
    # Anyone can call this!
    pass

Implement Proper Authorization

Authentication (who you are) is not enough - check authorization (what you can do):

@app.delete("/api/users/{user_id}")
@require_auth
async def delete_user(user_id: str, request: Request):
    current_user = get_current_user(request)

    # Authorization check
    if not current_user.is_admin and current_user.id != user_id:
        raise HTTPException(status_code=403, detail="Forbidden")

    # Proceed with deletion
    await delete_user_by_id(user_id)

Use Strong Token Standards

Use industry-standard tokens:

# Good - JWT with expiration
import jwt
from datetime import datetime, timedelta

def create_access_token(user_id: str) -> str:
    payload = {
        "sub": user_id,
        "exp": datetime.utcnow() + timedelta(hours=1),
        "iat": datetime.utcnow(),
    }
    return jwt.encode(payload, SECRET_KEY, algorithm="HS256")

# Validate tokens properly
def verify_token(token: str) -> dict:
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=["HS256"])
        return payload
    except jwt.ExpiredSignatureError:
        raise HTTPException(status_code=401, detail="Token expired")
    except jwt.InvalidTokenError:
        raise HTTPException(status_code=401, detail="Invalid token")