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

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Main Configuration Areas

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Mode

Choose whether the workflow is reversible:
  • pseudonymize for encrypted mappings and later rehydration
  • anonymize for irreversible protection

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Detection

Control which detectors are active:
  • Built-in regex recognizers
  • Optional NER model
  • Custom recognizers and custom ID patterns

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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)

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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.

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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

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Example

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,
  }
});

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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.

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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

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Next Steps

createAnonymizer

Review the full SDK configuration surface.

Recognizers

Understand the detection layer you are configuring.