> ## Documentation Index
> Fetch the complete documentation index at: https://docs.zylon.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Guardrails

> Create regex-based guardrails and assign them to gateways to block AI requests that match sensitive patterns.

## Overview

**Guardrails** let Operators define rules that inspect AI traffic flowing through a gateway. When a guardrail is triggered, the AI request is **blocked** before it reaches the model.

Guardrails are useful to prevent sensitive or non-compliant data (such as national IDs, bank accounts, or credit cards) from being sent to the AI, helping you enforce data protection and compliance policies.

Each guardrail is:

* **Assigned to one or more gateways**, so it only applies to the traffic of those gateways.
* **Evaluated on every AI request** handled by the assigned gateways.
* **Blocking**: when the guardrail matches, the request is rejected.

<Note>
  For now, guardrails support **regular expressions (regex)** only. Additional guardrail types may be added in the future.
</Note>

Only users with the **Operator** role can manage guardrails. Availability and limits depend on the active license.

## How guardrails work

A guardrail contains one or more **regex patterns**. On each AI request routed through an assigned gateway:

1. The request content is checked against the guardrail's regex patterns.
2. If **any** pattern matches, the guardrail is triggered.
3. The AI request is **blocked** and does not reach the model.

Because regex guardrails run locally as a text match, they add virtually no latency to the request.

## Create a guardrail

To create a guardrail:

1. Open **Guardrails** in the Platform Backoffice.
2. Click **Add guardrail**.
3. Enter a **name** and an optional **description**.
4. Select the **gateways** this guardrail should apply to.
5. Add one or more **regex** patterns. Use **Add regex** to define multiple patterns in the same guardrail.
6. Save the guardrail.

Once saved, the guardrail is active on every assigned gateway and starts blocking matching requests immediately.

## Manage guardrails

From the guardrails list you can review each guardrail's name, description, type, effect, and the gateways it is assigned to.

* **Edit** a guardrail to update its patterns or reassign it to different gateways.
* **Delete** a guardrail to stop it from blocking requests.

## Regex examples

The table below lists common regex patterns you can use as a starting point for your guardrails. Adjust them to match the exact formats used in your organization.

| Data type                      | Example regex                                        |
| ------------------------------ | ---------------------------------------------------- |
| Spanish DNI                    | `\b\d{8}[A-Za-z]\b`                                  |
| Spanish NIE                    | `\b[XYZ]\d{7}[A-Za-z]\b`                             |
| IBAN (bank account)            | `\b[A-Z]{2}\d{2}[A-Z0-9]{11,30}\b`                   |
| Spanish CCC (bank account)     | `\b\d{4}[ -]?\d{4}[ -]?\d{2}[ -]?\d{10}\b`           |
| Credit card number             | `\b(?:\d[ -]?){13,16}\b`                             |
| Email address                  | `\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}\b` |
| Phone number (Spain)           | `(?:\+34\|0034)?[ -]?[6-9]\d{2}[ -]?\d{3}[ -]?\d{3}` |
| Spanish social security number | `\b\d{2}[ -]?\d{8}[ -]?\d{2}\b`                      |
| IPv4 address                   | `\b(?:\d{1,3}\.){3}\d{1,3}\b`                        |

### Copy-ready regex snippets

Use the code blocks below when you want a one-click copy action.

#### Spanish DNI

```txt theme={null}
\b\d{8}[A-Za-z]\b
```

#### Spanish NIE

```txt theme={null}
\b[XYZ]\d{7}[A-Za-z]\b
```

#### IBAN

```txt theme={null}
\b[A-Z]{2}\d{2}[A-Z0-9]{11,30}\b
```

#### Spanish CCC

```txt theme={null}
\b\d{4}[ -]?\d{4}[ -]?\d{2}[ -]?\d{10}\b
```

#### Credit card number

```txt theme={null}
\b(?:\d[ -]?){13,16}\b
```

#### Email address

```txt theme={null}
\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}\b
```

#### Phone number (Spain)

```txt theme={null}
(?:\+34|0034)?[ -]?[6-9]\d{2}[ -]?\d{3}[ -]?\d{3}
```

#### Spanish social security number

```txt theme={null}
\b\d{2}[ -]?\d{8}[ -]?\d{2}\b
```

#### IPv4 address

```txt theme={null}
\b(?:\d{1,3}\.){3}\d{1,3}\b
```

<Warning>
  Regex patterns are matched exactly as written. Always test your patterns against representative data to avoid false positives (blocking valid requests) or false negatives (letting sensitive data through).
</Warning>