> ## Documentation Index
> Fetch the complete documentation index at: https://docs.wafer.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Zero Data Retention

> Require ZDR on individual Wafer Serverless requests.

Serverless keys do not require Zero Data Retention (ZDR) by default. To require ZDR for a Serverless request, send `Wafer-ZDR: required`.

```bash theme={null}
curl -sS "https://pass.wafer.ai/v1/chat/completions" \
  -H "Authorization: Bearer <YOUR_WAFER_API_KEY>" \
  -H "Wafer-ZDR: required" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "GLM-5.1",
    "messages": [{"role": "user", "content": "Hello!"}]
  }'
```

If the selected model supports ZDR, Wafer routes the request normally. If the selected model does not support ZDR, Wafer rejects the request before routing it upstream and returns `model_zdr_not_supported`.

Some GUI harnesses do not expose custom request headers. For those apps, use a harness-specific custom header path when available (for example, Claude Code's `ANTHROPIC_CUSTOM_HEADERS`) so ZDR can still be enforced per request.