> For the complete documentation index, see [llms.txt](https://docs.uptiq.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.uptiq.ai/platform-resources/skill-library/ai-skills/pii-guard.md).
# PII Guard
**PII Guard** detects standard personally identifiable information in raw text and replaces it with generic placeholders — `[SSN]`, `[EMAIL]`, `[PHONE]` — so sensitive data is anonymized before further processing, storage, or transmission.
Use it at the boundary: after data arrives from an external system, and before it reaches somewhere you'd rather it didn't — a log, a less-trusted service, or a model.
## How it works
* **Input resolution** — `$input` (the previous skill's output). `$secret` is available but not typically needed here.
* **Processing** — accepts raw text or JSON-stringified free-form content, identifies standard PII patterns, and returns the text with placeholders inserted:
| Detected | Replaced with |
| ------------- | ------------- |
| Email address | `[EMAIL]` |
| SSN | `[SSN]` |
| Phone number | `[PHONE]` |
* **Execution** — blocking. Completes before the workflow proceeds.
* **Response** — success returns `maskedData` with the redacted text; failure returns an error message and status code.
## Worked example: masking PII from a database query
A workflow queries a customer record — through an API call or a database query — and gets back a text string containing a name, an SSN, and an email address. Before that string reaches a log file or an LLM for analysis, the PII should be gone.
**The problem.** Data retrieved from external systems arrives with sensitive fields you don't want exposed or stored unmasked further downstream.
**The approach.** Put a PII Guard immediately after the step that produces the text. It has one field to configure: **Text to Scan for PII** (`input` in the schema), which you point at the previous skill's output — `$input.data.customerDetailsString`.
Specifying the text input for PII Guard
**In:**
> Hello, this is Michael. My SSN is 123-45-6789 and my email is . Please call me at (555) 123-4567 or +1-800-555-1212.
**Out:**
> Hello, this is Michael. My SSN is \[SSN] and my email is \[EMAIL]. Please call me at \[PHONE] or \[PHONE].
{% hint style="info" %}
PII Guard masks the **standard patterns** it knows — email, SSN, phone. It is not a general-purpose classifier: a customer name, an account number, or a bank-specific identifier passes through untouched. When you need domain-specific extraction, pair it with [Entity Recognition](/platform-resources/skill-library/ai-skills/entity-recognition.md) and its custom regex rules.
{% endhint %}
## Configuration reference
| Field | Type | Required | Description |
| ------------- | ------ | -------- | -------------------------------- |
| `input` | any | ✅ | Free-form text to scan and mask. |
| `name` | string | — | Name for this skill instance. |
| `description` | string | — | Description of what it's doing. |
## Output
The output port (`piiMaskedResult`) always conforms to:
| Field | Type | Always | Description |
| ------------ | -------------- | ------ | ----------------------------------------------------------- |
| `maskedData` | any | ✅ | The redacted input, PII replaced by placeholders. |
| `error` | string \| null | — | Error message if processing failed; `null` on success. |
| `statusCode` | number | ✅ | `200` success · `400` invalid input · `500` internal error. |
**Failure — invalid input:**
```json
{
"maskedData": null,
"error": "Invalid input: expected non-empty string.",
"statusCode": 400
}
```
## Errors
| Message | Status | Cause |
| ------------------------------- | ------ | --------------------------------- |
| Invalid input | `400` | Null or undefined input. |
| Masking failed due to exception | `500` | Internal error during processing. |
## Security
* No `$secret` usage is required.
* **Make sure your logging and debugging tools don't log the unmasked input.** The skill masks in memory before passing data on — but that only protects what happens *after* it.
* Masking is in-memory. No unmasked data is persisted by the skill itself.
PII Guard's in-memory processing flow
## Testing in isolation
* **Path** — `/skill-runtime/workflows/nodes/PIIGuard/execute`
* **Method** — `POST`
* **Body:**
```json
{
"config": { "input": "I am John. Email: john.doe@example.com. SSN: 123-45-6789" },
"input": {}
}
```
***
To add this skill to an agent, see [Adding a Skill to the Agent](/agent-builder/build/adding-a-skill-to-the-agent.md). For platform-level PII handling, see [PII Tokenization](broken://pages/ZryZVAnzLvPXJXz1em2n).
---
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