Is Helicone just for monitoring, or can it actually throttle bad actors?

I've been running Helicone in front of our LLM workloads (mostly OpenAI, some Anthropic) for about four months now. The initial pitch was clear: cost monitoring, per-user/per-key analytics, and a decent proxy layer. It delivers on that. The dashboards are useful, and the Prometheus export is solid.

But here's my blunt assessment: its "anomaly detection" and "safety" features are marketing fluff until you configure them aggressively. Out of the box, it logs and alerts. It does not, by default, *prevent* anything.

The real question is whether you can bend it into a rudimentary throttling and abuse mitigation system. The answer is yes, but you're going to be writing the logic yourself via their "custom properties" and "rate limits." It's a framework, not a solution.

Here's what I've built to stop bad actors and cost overruns:

**1. Proactive Rate Limiting by Custom Property**
You can tag requests with a `userId` or `sessionId`. The built-in rate limiting is per-key. To throttle a specific user across keys, you need to feed that into a custom property and then set limits on *that*.

```yaml
# Example Helicone rate limit policy (conceptual, via their dashboard)
Limit Type: Custom Property
Property Key: `helium_user_id`
Limits:
- Requests: 1000 per 24h
- Tokens: 500000 per 24h
Action: Block Request
```

**2. Cost-Based Hard Stops**
This is where it gets useful. You can set absolute cost limits per key or per custom property.

```
if (costToday(customProperty="api_key") > $50.00) {
blockRequest();
}
```

We have this on every staging key and for our free-tier users. It saved us from a $2k mistake when a bug started looping.

**3. The "Anomaly" Gap**
Their anomaly detection flags spikes in latency, cost, or errors. It sends a webhook. That's it. To make it "throttle," you must consume that webhook, parse the offending key/user, and *programmatically* update their rate limit via Helicone's API to zero. It's a two-step manual process.

**Performance Impact?**
Negligible. Adding ~3-5ms latency at the proxy. The bigger cost is the data pipeline. If you're logging every request with full payloads for audit, your egress and storage costs will climb. You must tune sampling.

**Conclusion:**
* **Monitoring & Analytics:** Excellent. 9/10.
* **Out-of-the-box Throttling:** Basic (per-key rate limits only). 5/10.
* **Build-Your-Own-Throttling:** Possible, but requires engineering effort. You get the levers (custom properties, cost limits, API-driven policies), but you pull them. 7/10 for capability, 4/10 for ease.

If you need to stop abuse, you'll be writing code around Helicone, not just configuring it. For simple per-key limits and cost ceilings, it works. For anything resembling sophisticated actor detection, you're on your own.

—DL