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

# Configuration

> How Rehydra settings shape detection, output, and runtime behavior

Rehydra configuration controls what gets detected, how text is protected, and whether the workflow is reversible.

## Main Configuration Areas

### Mode

Choose whether the workflow is reversible:

* `pseudonymize` for encrypted mappings and later rehydration
* `anonymize` for irreversible protection

### Detection

Control which detectors are active:

* Built-in regex recognizers
* Optional NER model
* Custom recognizers and custom ID patterns

### Policy

Policies shape detection behavior for each call or as a default:

* Enabled regex and NER types
* Confidence thresholds
* Type priority for overlaps
* Allowlists and denylists
* ID reuse behavior
* Leak scanning and semantic masking
* Location scope exclusions (skip countries/regions)

### Tag Format

By default, PII placeholders use XML-style tags: `<PII type="EMAIL" id="1"/>`. You can customize the delimiters and keyword:

* `tagFormat.open` / `tagFormat.close` — delimiter characters (e.g., `[[` / `]]`)
* `tagFormat.keyword` — the keyword inside tags (default: `PII`)

This is useful when XML-style tags conflict with your processing pipeline (e.g., HTML sanitizers, XML parsers) or when you need a format that's less likely to be mangled by translation services.

### Runtime Integrations

Configuration also covers runtime behavior such as:

* Key providers for reversible workflows
* Storage providers for sessions
* NER model backend and download settings
* Semantic enrichment options

## Example

```typescript theme={null}
import { createAnonymizer, PIIType } from 'rehydra';

const anonymizer = createAnonymizer({
  mode: 'pseudonymize',
  ner: { mode: 'quantized' },
  semantic: { enabled: false },
  tagFormat: { open: '[[', close: ']]' }, // optional: bracket-style placeholders
  defaultPolicy: {
    regexEnabledTypes: new Set([PIIType.EMAIL, PIIType.PHONE]),
    nerEnabledTypes: new Set([PIIType.PERSON]),
    enableLeakScan: true,
  }
});
```

## Configuration Levels

Rehydra settings typically live at two levels:

* `createAnonymizer()` configuration for reusable defaults
* Per-call policy overrides when a specific operation needs different rules

This lets you keep a stable baseline while still adapting behavior for individual workflows.

## Keep Concepts Separate

It helps to think about configuration in layers:

* Mode decides reversibility
* Recognizers decide what can be found
* Policy decides what should be found right now
* Tag format decides how placeholders look in output
* Key and storage settings decide how reversible data is managed

## Next Steps

<CardGroup cols={2}>
  <Card title="createAnonymizer" icon="plus" href="/api-reference/create-anonymizer">
    Review the full SDK configuration surface.
  </Card>

  <Card title="Recognizers" icon="scan-search" href="/concepts/recognizers">
    Understand the detection layer you are configuring.
  </Card>
</CardGroup>