"}],
max_depth=5,
)
```
## Use a custom function
If your redaction logic is more complex, pass a function instead of a list of patterns. The function receives a string and returns the redacted string:
```python Python theme={null}
import re
from langsmith.anonymizer import create_anonymizer
from langsmith import Client
# Example: redact any value that follows a known key name in JSON-like payloads
SECRET_KEYS = {"api_key", "apiKey", "token", "secret", "password", "credential"}
def redact_secret_values(text: str) -> str:
for key in SECRET_KEYS:
# Match patterns like: "api_key": "some-value"
pattern = rf'("{key}"\s*:\s*)"[^"]*"'
text = re.sub(pattern, r'\1""', text)
return text
anonymizer = create_anonymizer(redact_secret_values)
client = Client(anonymizer=anonymizer)
```
```typescript TypeScript theme={null}
import { createAnonymizer } from "langsmith/anonymizer";
import { Client } from "langsmith";
const SECRET_KEYS = new Set(["api_key", "apiKey", "token", "secret", "password", "credential"]);
function redactSecretValues(text: string): string {
for (const key of SECRET_KEYS) {
// Match patterns like: "api_key": "some-value"
const pattern = new RegExp(`("${key}"\\s*:\\s*)"[^"]*"`, "g");
text = text.replace(pattern, '$1""');
}
return text;
}
const anonymizer = createAnonymizer(redactSecretValues);
const client = new Client({ anonymizer });
```
## Combine with LANGSMITH\_HIDE\_INPUTS
If your use case requires completely suppressing all inputs (for example, for zero-retention compliance), use `LANGSMITH_HIDE_INPUTS=true` instead. The anonymizer is skipped when `LANGSMITH_HIDE_INPUTS` or `LANGSMITH_HIDE_OUTPUTS` is set to `true`.
For more options, including hiding all inputs and outputs, hiding metadata, function-level processors, and third-party PII libraries, see [Prevent logging of sensitive data in traces](/langsmith/mask-inputs-outputs).
***
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