ai-prompt-sanitizer 0.1.0

Lightweight, tiered, bidirectional PII sanitizer for LLM pipelines

prompt-sanitizer

PII and secret sanitization for Python LLM pipelines.

prompt-sanitizer provides a typed API for detecting, redacting, anonymizing, and restoring sensitive values before they reach a model, tool, middleware layer, log sink, or SDK wrapper. FAST mode has zero required dependencies. SMART and FULL add optional NLP, synthetic replacement, and audit logging.

Install

Python 3.10+.

pip install prompt-sanitizer
pip install "prompt-sanitizer[nlp]"
pip install "prompt-sanitizer[synthetic]"
pip install "prompt-sanitizer[integrations]"
pip install "prompt-sanitizer[all]"

Optional extras

Extra	Adds	Typical use
nlp	transformers + torch	NER in SMART/FULL mode
synthetic	faker	realistic fake replacements
integrations	framework / SDK adapters	LangChain, LlamaIndex, OpenAI, FastAPI, Django
all	all extras	full feature set

Quick start

from prompt_sanitizer import Sanitizer, Mode

s = Sanitizer(mode=Mode.FAST)
result = s.sanitize("Contact Jane Doe at [e-mail] or 415-555-0112.")

print(result.text)
print(result.has_pii)
print(result.risk_score)
print(result.tokens)
for entity in result.entities:
    print(entity.entity_type, entity.value, entity.replacement)

Modes

Mode	Pipeline	Dependencies	Notes
Mode.FAST	regex + secret detectors	none	sub-ms, stdlib only
Mode.SMART	FAST + Piiranha NER	prompt-sanitizer[nlp]	lazy-loads on first call
Mode.FULL	SMART + synthetic replacement + audit log	usually nlp + synthetic	best for compliance-oriented flows

FAST mode

from prompt_sanitizer import Sanitizer, Mode

s = Sanitizer(mode=Mode.FAST)
text = "SSN 078-05-1120, card 4111 1111 1111 1111, token sk-proj-xxxxxxxxxxxxxxxxxxxxxxxx"
result = s.sanitize(text)

print(result.text)
print(result.entities)
print(result.tokens)

Use FAST for prompt pre-processing, log scrubbing, middleware guards, CI checks, and zero-dependency CLI tooling.

SMART mode

from prompt_sanitizer import Sanitizer, Mode

s = Sanitizer(mode=Mode.SMART)
result = s.sanitize(
    "Alice from Acme Corp met us in Berlin on 2025-02-14. Email [e-mail]."
)

print(result.text)
for entity in result.entities:
    print(entity.entity_type, entity.value, entity.confidence)

Use SMART when prompts contain free-form prose with names, organizations, dates, or locations that regexes alone may miss.

FULL mode

from prompt_sanitizer import Sanitizer, Mode, SQLiteAuditLog

audit = SQLiteAuditLog("prompt_sanitizer_audit.db")
s = Sanitizer(mode=Mode.FULL, locale="en_US", on_detect="redact", audit_log=audit)

result = s.sanitize("Customer Jane Doe uses [e-mail] and 415-555-0112.")
print(result.text)
print(result.tokens)
print(s.audit.export(format="json"))

Use FULL when you want synthetic replacement plus an audit trail.

Public API

Sanitizer

Sanitizer(
    mode: Mode = Mode.FAST,
    locale: str = "en_US",
    entities: list[EntityType] | None = None,
    on_detect: str = "redact",
    audit_log: BaseAuditLog | None = None,
)

Parameter	Type	Description
mode	Mode	detection pipeline
locale	str	locale for synthetic replacement generation
entities	list[EntityType] | None	optional allowlist of entity types
on_detect	str	"redact", "warn", or "block"
audit_log	BaseAuditLog | None	optional audit backend

Method	Signature	Description
sanitize	`sanitize(text: str, session_id: str	None = None) -> SanitizeResult`
sanitize_batch	sanitize_batch(texts: list[str]) -> list[SanitizeResult]	sanitize multiple inputs
session	`session(session_id: str	None = None) -> Session`
add_entity	add_entity(name: str, pattern: str, confidence: float = 0.85) -> None	register a custom entity
stream	`stream(source: AsyncIterable, session: Session	None) -> AsyncGenerator[str, None]`
guard	guard(on_detect: str) -> decorator	decorate a function with sanitization logic
audit	`.audit -> BaseAuditLog	None`

Detection policy

on_detect value	Behavior
"redact"	rewrite the returned text
"warn"	return original text, but populate entities and scores
"block"	raise instead of returning sanitized text

results = s.sanitize_batch(["Email [e-mail]", "No sensitive data here"])

@s.guard(on_detect="redact")
def call_model(prompt: str) -> str:
    return prompt

---

Mode, SanitizeResult, and DetectedEntity

Mode value	Meaning
Mode.FAST	regex + secrets, zero deps, sub-ms
Mode.SMART	FAST + Piiranha NER, lazy loads on first call
Mode.FULL	SMART + synthetic replacement + audit log

SanitizeResult attribute	Type	Description
text	str	sanitized text
entities	list[DetectedEntity]	detected spans
tokens	dict[str, str]	{original_value: replacement} map
risk_score	float	composite score from 0.0 to 1.0
has_pii	bool	whether sensitive data was found

DetectedEntity attribute	Type	Description
entity_type	EntityType	entity classification
value	str	original matched value
start	int	inclusive start offset
end	int	exclusive end offset
confidence	float	detection confidence
replacement	str | None	replacement value, if generated

result = s.sanitize("Contact me at [e-mail]")
assert result.has_pii is True
assert 0.0 <= result.risk_score <= 1.0
for entity in result.entities:
    print(entity.entity_type, entity.value, entity.replacement)

Sessions and vaults

Use sessions when the model should never see raw values, but the final response should restore them.

from prompt_sanitizer import Sanitizer

s = Sanitizer()
session = s.session(session_id="support-chat-001")
clean_prompt = session.anonymize("My name is Elena Ruiz and my email is [e-mail]")
llm_reply = "Confirmed. I will email [EMAIL_1] shortly."
final_reply = session.deanonymize(llm_reply)

print(clean_prompt)
print(final_reply)

Session API	Description
session.anonymize(text: str) -> str	replace PII with vault tokens
session.deanonymize(text: str) -> str	restore originals from the vault
session.vault: Vault	access the underlying vault

Vault API	Description
vault.store(value: str, replacement: str) -> None	store a mapping
vault.lookup(replacement: str) -> str | None	resolve token to original
vault.reverse(value: str) -> str | None	resolve original to replacement
vault.clear() -> None	clear all mappings

vault = session.vault
vault.store("[e-mail]", "[EMAIL_1]")
print(vault.lookup("[EMAIL_1]"))
print(vault.reverse("[e-mail]"))
vault.clear()

Custom entities

Use add_entity() for internal identifiers, tenant-specific secrets, or domain-specific formats.

from prompt_sanitizer import Sanitizer

s = Sanitizer()
s.add_entity(name="customer_id", pattern=r"\bCUS-\d{8}\b", confidence=0.90)
s.add_entity(name="invoice_no", pattern=r"\bINV-\d{6}-[A-Z]{2}\b", confidence=0.88)

result = s.sanitize("Customer CUS-12345678 opened invoice INV-882211-US")
print(result.text)
print(result.entities)

Filtering by entity type

from prompt_sanitizer import Sanitizer, EntityType

s = Sanitizer(entities=[EntityType.EMAIL, EntityType.API_KEY])
result = s.sanitize("Email [e-mail] and SSN 123-45-6789")
print(result.text)

Audit logging

Audit backends are optional. Use them when you want structured records of detections.

MemoryAuditLog

from prompt_sanitizer import MemoryAuditLog, Mode, Sanitizer

audit = MemoryAuditLog()
s = Sanitizer(mode=Mode.FULL, audit_log=audit)
s.sanitize("Email [e-mail]")

print(audit.events())
print(audit.export(format="json"))

SQLiteAuditLog

from prompt_sanitizer import SQLiteAuditLog, Mode, Sanitizer

audit = SQLiteAuditLog("audit.db")
s = Sanitizer(mode=Mode.FULL, audit_log=audit)
s.sanitize("Call [phone]", session_id="request-17")

print(audit.events())
print(audit.export(format="csv"))

Audit API

API	Description
MemoryAuditLog()	in-memory list of AuditEvent
SQLiteAuditLog(path: str)	SQLite-backed persisted log
.events() -> list[AuditEvent]	return recorded events
.export(format: "json" | "csv") -> str	export audit records

Integrations

Install integration dependencies first:

pip install "prompt-sanitizer[integrations]"

LangChain

from prompt_sanitizer import Sanitizer
from prompt_sanitizer.integrations.langchain import PromptSanitizerRunnable, SanitizedLLM

s = Sanitizer()
# As a runnable step in a chain
chain = PromptSanitizerRunnable(sanitizer=s) | llm | OutputParser()
result = chain.invoke("My email is [e-mail]")

# Or wrap the LLM directly
safe_llm = SanitizedLLM(llm, s)
reply = safe_llm.invoke("Contact [e-mail] with the summary.")

LlamaIndex

from prompt_sanitizer import Sanitizer
from prompt_sanitizer.integrations.llamaindex import PromptSanitizerPostprocessor

s = Sanitizer()
postprocessor = PromptSanitizerPostprocessor(sanitizer=s)
query_engine = index.as_query_engine(node_postprocessors=[postprocessor])
response = query_engine.query("Summarize the contract for [e-mail]")

OpenAI SDK wrapper

import openai
from prompt_sanitizer import Sanitizer
from prompt_sanitizer.integrations.openai import wrap

s = Sanitizer()
client = wrap(openai.OpenAI(), sanitizer=s)
response = client.chat.completions.create(
    model="gpt-4o-mini",
    messages=[{"role": "user", "content": "My card is 4111 1111 1111 1111"}],
)

FastAPI middleware

from fastapi import FastAPI
from prompt_sanitizer import Sanitizer
from prompt_sanitizer.integrations.fastapi import SanitizerMiddleware

s = Sanitizer()
app = FastAPI()
app.add_middleware(SanitizerMiddleware, sanitizer=s, fields=["prompt", "message"])

Django middleware

MIDDLEWARE = ["prompt_sanitizer.integrations.django.SanitizerMiddleware"]

from prompt_sanitizer import Sanitizer

PROMPT_SANITIZER = {
    "sanitizer": Sanitizer(),
    "fields": ["prompt", "message"],
}

Entity types

Group	Values
core PII	EMAIL, PHONE, SSN, CREDIT_CARD, IBAN, IP_ADDRESS, URL, DATE
identity / org	PERSON_NAME, ORGANIZATION, LOCATION
secrets	API_KEY, JWT_TOKEN, SECRET_KEY, AWS_KEY, GITHUB_TOKEN, OPENAI_KEY, ANTHROPIC_KEY
extension	CUSTOM

---

Operational notes

• FAST mode is stdlib-only.
• SMART lazy-loads NER on first use.
• FULL is the best fit for synthetic replacement plus audit.
• sanitize() is for one-shot calls.
• session() is for reversible multi-turn workflows.
• sanitize_batch() treats each input independently.

License

MIT.