What is the difference between circuit breaker and rate limiting?

Question

Accepted Answer

**Circuit Breaker** — prevent cascading failures. **Rate Limiting** — control request rate.

**Circuit Breaker:**
- Detects failures.
- Opens circuit on failure threshold.
- Prevents cascading failures.
- Allows recovery.

```
Circuit Breaker:
Normal: Requests flow through
Failure threshold: Circuit opens
Open: Requests fail fast
Half-open: Test if recovered
(Prevents cascading failures)
```

**Rate Limiting:**
- Controls request frequency.
- Prevents abuse.
- Token bucket, sliding window.
- Returns 429 on limit.

```
Rate Limiting:
100 requests per minute
Request 101: 429 Too Many Requests
(Controls traffic)
```

**Key differences:**
- **Circuit Breaker** — failure protection.
- **Rate Limiting** — traffic control.
- **Circuit Breaker** — for dependent services.
- **Rate Limiting** — for API consumers.

Systems Analyst: What is the difference between circuit breaker and rate limiting?