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The Rehydra CLI lets you anonymize files and piped text directly from the terminal — no code required.

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Installation

The CLI is published as a separate lightweight package: 
npm install -g @rehydra/cli
Or run directly without installing globally: 
npx @rehydra/cli anonymize input.txt
The CLI requires Node.js 18+ and depends on the rehydra SDK package (installed automatically).

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Commands

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anonymize

Detect and replace PII in a file or stdin. 
# Anonymize a file
rehydra anonymize input.txt -o output.txt

# Pipe from stdin
echo "Contact john@example.com" | rehydra anonymize

# With NER (detects names, orgs, locations)
rehydra anonymize input.txt --ner quantized

# JSON output
rehydra anonymize input.txt -f json

# Only detect specific types
rehydra anonymize input.txt --types EMAIL,PHONE,IBAN

# Irreversible mode (no PII map saved)
rehydra anonymize input.txt --mode anonymize
By default, the anonymize command:
  • Uses regex-only detection (no NER)
  • Runs in pseudonymize mode (saves an encrypted PII map for later rehydration)
  • Writes the PII map to .rehydra-pii-map.json
  • Generates a random encryption key and stores it in the PII map file

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rehydrate

Restore original PII values from anonymized text using the saved PII map. 
# Rehydrate using the default PII map file
rehydra rehydrate anonymized.txt

# Specify a PII map file
rehydra rehydrate anonymized.txt --pii-map my-pii-map.json

# Use an explicit key (if not stored in the PII map file)
rehydra rehydrate anonymized.txt --key <base64-key>
The encryption key is resolved in order: --key flag, REHYDRA_KEY environment variable, then the key embedded in the PII map file.

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inspect

Dry-run that shows detected PII highlighted in context without anonymizing. Useful for previewing what will be detected. 
# Inspect a file
rehydra inspect input.txt

# With NER
rehydra inspect input.txt --ner quantized
Output shows the original text with PII highlighted and labeled by type using color coding.

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proxy

Start a local HTTP proxy that anonymizes PII in requests to LLM APIs and rehydrates PII in responses. 
# Start proxy for Anthropic (Claude Code, Cursor, etc.)
rehydra proxy anthropic

# Start proxy for OpenAI
rehydra proxy openai

# "claude" is an alias for "anthropic"
rehydra proxy claude

# Custom port
rehydra proxy anthropic -p 9000

# Inject an API key (bridges OAuth clients to API key auth)
rehydra proxy anthropic --api-key sk-ant-...

# Or set the key via environment variable
export LLM_API_KEY=sk-ant-...
rehydra proxy anthropic
Supported providers: openai, anthropic, claude (alias for anthropic)

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How It Works

  1. The proxy starts immediately with regex-only detection so there’s no startup delay
  2. In the background, the NER model downloads (if needed) and loads
  3. Once NER is ready, the proxy hot-swaps to regex + NER detection — no restart required
The --ner flag defaults to quantized for the proxy command (unlike other commands which default to disabled). Pass --ner disabled to use regex-only detection.

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Connecting Your Tools

The proxy prints connection instructions on startup. Here are the common setups: 
ANTHROPIC_BASE_URL=http://127.0.0.1:8787 claude

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API Key Injection

Use --api-key (or the LLM_API_KEY environment variable) to inject an API key into upstream requests. This is useful when your tool authenticates via OAuth but the upstream API requires an API key: 
# Claude Code with Max uses OAuth — bridge it to API key auth
rehydra proxy claude --api-key sk-ant-...
ANTHROPIC_BASE_URL=http://127.0.0.1:8787 claude
The proxy uses in-memory storage — PII maps are not persisted to disk. Each proxy session starts fresh.

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setup-ner

Download the NER model ahead of time so anonymize/inspect don’t need to download on first use. 
# Download quantized model (~280 MB)
rehydra setup-ner

# Download standard model (~1.1 GB)
rehydra setup-ner --ner standard

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Round-Trip Example

# 1. Anonymize
rehydra anonymize letter.txt -o anonymized.txt --ner quantized

# 2. Process the anonymized text (e.g., translate externally)
# ... PII placeholders are preserved by most tools ...

# 3. Rehydrate
rehydra rehydrate translated.txt -o final.txt

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Options Reference

FlagShortDefaultDescription
--output <file>-ostdoutOutput file
--format <fmt>-ftextOutput format: text, json, ndjson
--ner <mode>disabledNER mode: disabled, quantized, standard
--pii-map <file>.rehydra-pii-map.jsonPII map file path
--key <key>Encryption key (base64), or set REHYDRA_KEY env var
--types <types>allComma-separated PII types to detect
--mode <mode>pseudonymizepseudonymize (reversible) or anonymize (irreversible)
--locale <locale>Locale hint (e.g., de-DE)
--secretsEnable secrets/credentials detection
--env-file <file>.env file path for literal value redaction
--port <port>-p8787Proxy port (proxy command)
--upstream <url>Custom upstream URL, overrides provider default (proxy command)
--api-key <key>LLM API key for upstream, or set LLM_API_KEY env var (proxy command)
--tag-open <str><Tag open delimiter
--tag-close <str>/>Tag close delimiter
--tag-keyword <str>PIITag keyword
--no-colorDisable colored output
--verboseShow detection statistics
--quiet-qSuppress non-essential output
--help-hShow help
--version-VShow version

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Custom Tag Format

By default, placeholders use XML-style tags: <PII type="EMAIL" id="1"/>. Use --tag-open, --tag-close, and --tag-keyword to change the format: 
# Bracket-style: [[PII type="EMAIL" id="1"]]
rehydra anonymize input.txt --tag-open '[[' --tag-close ']]'

# Custom keyword: {{REDACTED type="EMAIL" id="1"}}
rehydra anonymize input.txt --tag-open '{{' --tag-close '}}' --tag-keyword REDACTED
The same flags work with rehydrate, inspect, and proxy. Use matching flags during rehydration: 
rehydra anonymize input.txt -o anon.txt --tag-open '[[' --tag-close ']]'
rehydra rehydrate anon.txt --tag-open '[[' --tag-close ']]'

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Output Formats

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text (default)

Returns the anonymized text as-is: 
Contact <PII type="EMAIL" id="1"/> or call <PII type="PHONE" id="1"/>.

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json

Structured JSON with anonymized text, entities, and stats: 
{
  "anonymizedText": "Contact <PII type=\"EMAIL\" id=\"1\"/>...",
  "entities": [
    { "type": "EMAIL", "id": 1, "confidence": 0.95, "source": "REGEX" }
  ],
  "stats": {
    "totalEntities": 1,
    "countsByType": { "EMAIL": 1 },
    "processingTimeMs": 5
  }
}

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ndjson

One JSON line per entity, plus a summary line — useful for streaming pipelines: 
{"type":"EMAIL","id":1,"confidence":0.95,"source":"REGEX"}
{"_type":"summary","anonymizedText":"...","totalEntities":1,"processingTimeMs":5}

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Encryption Key Management

By default, rehydra anonymize generates a random key and embeds it in the PII map file. For production use, supply your own key: 
# Generate a key
openssl rand -base64 32

# Use via environment variable
export REHYDRA_KEY="your-base64-key"
rehydra anonymize input.txt

# Or via flag (key is NOT stored in the PII map file)
rehydra anonymize input.txt --key "your-base64-key"
rehydra rehydrate output.txt --key "your-base64-key"
When you provide a key via --key or REHYDRA_KEY, it is not written to the PII map file, keeping it separate from the encrypted data.

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Exit Codes

CodeMeaning
0Success (PII found and processed)
1Error
2Success but no PII detected

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Next Steps

Quick Start

Use Rehydra programmatically in your app

PII Types

See all PII types the CLI can detect