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

# PII/PHI Redaction

> PII/PHI Redaction transcribes audio, replaces sensitive spans with empty marker tags, and silences the matching audio ranges.

PII/PHI Redaction transcribes audio, replaces detected PII/PHI spans with empty marker tags (e.g. `<pii:name></pii:name>`, `<pii:ssn></pii:ssn>`, `<phi></phi>`) in the transcript, **and** silences the matching ranges in the returned audio.

|                             | Batch                              | Streaming                                    |
| --------------------------- | ---------------------------------- | -------------------------------------------- |
| **Use case**                | Transcription with audio redaction | Real-time transcription with audio redaction |
| **Protocol**                | HTTP POST                          | WebSocket                                    |
| **Languages**               | Multilingual                       | Multilingual                                 |
| **Speaker diarization**     | ✓                                  | ✓                                            |
| **PII/PHI audio redaction** | ✓                                  | ✓                                            |

<Note>
  Need PII/PHI flagged in the transcript but the **audio left intact**? Use the [STT APIs](/api-reference/stt/overview) with PII/PHI tagging instead.
</Note>

For a side-by-side comparison with the other Modulate capabilities, see [Which API should I use?](/guides/which-api).

## Authentication

Batch uses the `X-API-Key` header. Streaming uses an `api_key` query parameter at connection time. See [Authentication and rate limits](/guides/authentication).