PII redaction

ZeroEval supports opt-in source-side PII redaction in the Python and TypeScript SDKs. When enabled, sensitive values in ingested payload fields (input_data and output_data) are redacted before spans are sent by the SDK.

This is an SDK-side feature. ZeroEval does not rely on backend-side redaction for this behavior.

Enable redaction

Python
TypeScript

import zeroeval as ze

ze.init(
    api_key="YOUR_API_KEY",
    redaction={"enabled": True},
)

import * as ze from "zeroeval";

ze.init({
  apiKey: "YOUR_API_KEY",
  redaction: { enabled: true },
});

You can also enable the default redaction toggle with:

export ZEROEVAL_REDACT_PII=true

Python uses snake_case nested keys such as redact_inputs, sensitive_keys, and custom_patterns. TypeScript uses the camelCase equivalents redactInputs, sensitiveKeys, and customPatterns.

What gets redacted

Redaction applies to ingested payload fields only:

input_data (the value passed to setIO / set_io)
output_data (the value passed to setIO / set_io)

When wrapper integrations (OpenAI, Vercel AI, LangChain) serialize prompts and tool arguments into these IO fields, those values are also redacted. Built-in detectors cover:

email addresses
phone numbers
SSN-style identifiers
PAN / credit card numbers
bearer tokens, JWTs, and common API key formats
cookie and authorization header values
IP addresses

Key-based detection force-redacts common sensitive fields such as email, phone, password, token, authorization, cookie, and api_key / apiKey when they appear inside ingested IO payloads.

What stays intact

All span metadata outside of input_data and output_data is preserved unchanged:

span names
trace IDs and span IDs
timing and status fields
attributes
tags, trace tags, and session tags
session identifiers and session names
error messages and stacks
token counts, model/provider metadata, and cost metadata

Placeholder behavior

Sensitive values are replaced with stable placeholders inside a single trace:

[email protected] -> [REDACTED_EMAIL_A]
[email protected]   -> [REDACTED_EMAIL_B]
[email protected] -> [REDACTED_EMAIL_A]

the same normalized sensitive value in one trace gets the same placeholder
different values in the same trace get different placeholders
placeholder assignment resets per trace
matching is exact after normalization only
this is not fuzzy identity resolution

That means repeated references across parent and child spans stay joinable without preserving the original value.

Normalization and limitations

Type	Normalization used for placeholder reuse
Email	Trim + lowercase
Phone	Digits only
SSN / PAN	Digits only
IP	Canonical or lowercase string as implemented by each SDK
Secrets	Exact trimmed string

Important limitations:

there is no reversible backend token vault
there is no de-anonymization support
there is no fuzzy entity resolution across semantically related strings
bypassing SDK capture paths bypasses this protection

Examples

The SDK repositories include runnable examples. In both examples, only the values passed to set_io / setIO are redacted. Session metadata, tags, attributes, and error messages are sent unchanged.

Python
TypeScript

From zeroeval-sdk/examples/pii_redaction.py:

import zeroeval as ze

ze.init(
    api_key="sk_ze_demo_local",
    redaction={"enabled": True},
)

with ze.span(
    name="pii-redaction-demo",
    session={"id": "[email protected]", "name": "Alice [email protected]"},
    tags={"customer_email": "[email protected]"},
) as span:
    span.set_io(
        input_data={"email": "[email protected]", "phone": "+1 (415) 555-1234"},
        output_data={"result": "Reach [email protected]"},
    )

In the resulting span:

input_data.email becomes [REDACTED_EMAIL_A]
input_data.phone becomes [REDACTED_PHONE_A]
output_data.result contains [REDACTED_EMAIL_A]
session_id, session_name, and tags.customer_email stay as-is

From zeroeval-ts-sdk/examples/10-pii-redaction.ts:

import * as ze from "zeroeval";

ze.init({
  apiKey: "demo-api-key",
  redaction: { enabled: true },
});

const span = ze.tracer.startSpan("demo.pii_redaction", {
  sessionId: "[email protected]",
  sessionName: "Alice Example <[email protected]>",
  tags: { customer_email: "[email protected]" },
});

span.setIO(
  {
    email: "[email protected]",
    phone: "+1 (415) 555-1212",
    apiKey: "sk-live-abcdef1234567890",
  },
  "Send follow-up to [email protected] and [email protected]"
);

In the resulting span:

input_data contains [REDACTED_EMAIL_A], [REDACTED_PHONE_A], [REDACTED_SECRET_A]
output_data contains [REDACTED_EMAIL_A] and [REDACTED_EMAIL_B]
sessionId, sessionName, and tags.customer_email stay as-is

Repeated exact values such as the same email address reuse the same placeholder within a trace.

Tracing

Prompts

Feedback

Helpers

Enable redaction

What gets redacted

What stays intact

Placeholder behavior

Normalization and limitations

Examples

​Enable redaction

​What gets redacted

​What stays intact

​Placeholder behavior

​Normalization and limitations

​Examples

Enable redaction

What gets redacted

What stays intact

Placeholder behavior

Normalization and limitations

Examples