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

# Using text input validation

Users can configure **Text Input** fields to accept or restrict the type of data that recipients can enter based on a specific format, style, or number range. These validation settings are configured within the document preparation experience when sending out a signature request or creating, modifying, or utilizing a reusable template.

## Configuring text input validation

To configure the **Text Input** field validation settings within a signature request or reusable template:

1. Add a **Text Input** field to the request or template.
2. Select the **Text Input** field to configure field settings.
3. Click to expand the **Validation** section.
4. Select your validation option:
   * **Predefined validation types**: Choose from standard formats like numbers, email, dates, ZIP codes, or SSN.
   * **Custom (Regular Expression)**: Create your own validation pattern for organization-specific requirements. See [Custom (Regular Expression) validation](#custom-regular-expression-validation) for setup instructions and examples.

![Field Settings.png](https://mintcdn.com/product-docs/kY6O1CxZeJPunHf3/images/box-sign/Field-Settings.png?fit=max\&auto=format\&n=kY6O1CxZeJPunHf3\&q=85\&s=be1c94d94384d145ac8b61fc672ec32f)

![Validation.png](https://mintcdn.com/product-docs/kY6O1CxZeJPunHf3/images/box-sign/Validation.png?fit=max\&auto=format\&n=kY6O1CxZeJPunHf3\&q=85\&s=d7b7c2d052d525bc9f94ebd75f301316)

> [!NOTE]
>
> * Fields configured with text input validation cannot be configured as read-only fields and do not support multiple line data entry.
> * Predefined validations are supported via template tags, but the Custom (Regular Expression) option isn’t supported. For more information on template tags, see [Creating templates using tags](https://docs.box.com/en/box-sign/templates/creating-templates-using-tags.md). For more information on the Custom (Regular Expression) option, see [Custom (Regular Expression validation)](#custom-regular-expression-validation) below.
> * All text input validations are supported via public API. For more information, see the [Box Sign API Reference](https://developer.box.com/reference/resources/sign-request/).

## Supported validation types

The following table lists the various supported validation for **Text Input** fields:

| **Validation option** | **Validation requirements** | **Valid input example** |
| - | - | - |
| None (default option) | • No validation applied | N/A |
| Number | • Allow digits only (0-9) • No spaces allowed • No negative signs allowed • Optional decimal separator:   • Period (.)   • Comma (,) • Decimal separator cannot be followed or preceded by spaces or line breaks | • 12345 • 12,345 • 12.345 |
| Email | • Email syntax: [example@mail.com](mailto:example@mail.com) • Minimum input must follow the format **@**.\* where each \* represents any alphanumeric character (except the domain, which cannot start with a number). • No validation on the actual email address. | • [user@box.com](mailto:user@box.com) • [user100@box.com](mailto:user100@box.com) • [user@100box.com](mailto:user@100box.com) • [user@box.100.com](mailto:user@box.100.com) |
| Date | • YYYY-MM-DD (ISO Standard) (default option) • MM/DD/YYYY (US) • DD/MM/YYYY (UK, EU) • YYYY/MM/DD (JP, CH, KO) | • 2025-05-22 • 05/22/2025 • 22/05/2025 • 2025/05/22 |
| ZIP Code | • ZIP (US-based) (default option) • 5-digit numeric code: ##### • ZIP+4 (US-based)   • 9-digit numeric code: #####-#### • ZIP (JP-based)   • 7-digit numeric code: ###-#### | • 12345 • 12345-6789 • 100-0001 |
| SSN (Social Security Number) | • US based. • 9-digit numeric code: ###-##-#### | 000-00-0000 |
| Custom (Regular Expresion) | Custom regex pattern defined by sender. See [Custom (Regular Expression)](#custom-regular-expression-validation) section for details. | Varies based on pattern |

## Custom (regular expression) validation

Beyond the standard validation options, Box Sign offers a **Custom (Regular Expression)** option to customize validation for fields that need to meet requirements specific to your organization or region.

Custom validation uses **regular expressions (regex)**, which are sequences of characters that describe a specific pattern of allowed input for a field.

> [!NOTE]
>
> Custom regex validation is supported through the public API. For more information, see the [Box Sign API Reference](https://developer.box.com/reference/resources/sign-request/).

### Setting up custom validation

To configure custom validation:

1. Select **Custom (Regular Expression)** from the **Validation** dropdown menu.
2. Enter your regex pattern in the **Regular Expression Pattern** field. Provide an **Error Message** to display when the signer’s input is invalid.
3. (Recommended) Fill in the **Field Name (Label)** field to inform signers what data to populate in the field.

![Regex.png](https://mintcdn.com/product-docs/kY6O1CxZeJPunHf3/images/box-sign/Regex.png?fit=max\&auto=format\&n=kY6O1CxZeJPunHf3\&q=85\&s=50d191bad67243e07175ab3066079020)

Make sure your regex pattern uses a valid and supported format. Otherwise, you won't be able to apply the validation to the field. You might encounter two input errors: "Invalid pattern" if your regex pattern is invalid, or "Unsupported pattern" if your regex pattern is not supported by Box Sign guidelines. See [Regex pattern requirements](#regex-pattern-requirements) for supported syntax and limitations.

When the signer enters data, the system checks it against your pattern. If the input doesn't match, the field displays the error message you defined.

### Regex pattern requirements

To ensure your custom regex pattern works correctly, follow these guidelines:

**Supported characters:**

* Unicode letters (`\p{L}`)
* Unicode numbers (`\p{N}`)
* Whitespace (`\s`)
* Common punctuation: `- ( ) . , ' \ / @ _ : % ! ? ^`
* Common international currency symbols: `$ € £ ¥ ₹ ₩ ₽ ₺ ₫ ₴ ₱`

**Box Sign does not support the following regex patterns:**

* Matching back references (`\\[1-9]`)
* Nested quantifiers (`++, **`)
* Lookbehinds (`(?<=, (?<!`)
* Recursive and conditional checks (`(?R), (?&)`)

### Example regex patterns

Below are useful examples of valid and supported regex patterns:

#### Phone numbers

| Use case | Regex pattern | Description |
| - | - | - |
| US phone number | `^(\+1[-.\s]?)?(\(?\d{3}\)?)[-.\s]?\d{3}[-.\s]?\d{4}$` | Acceptable examples: • 123-456-7890 • (123) 456-7890 • 1234567890 • +1-123-456-7890 |
| Japan phone number | `^(\+81[-.\s]?)?(0?\d{1,4})[-.\s]?\d{1,4}[-.\s]?\d{4}$` | Acceptable examples: • 03-1234-5678 • 045-123-4567 • 090-1234-5678 • +81-90-1234-5678 |
| International format (flexible) | `^\+?[0-9][0-9\s.\-]{6,14}$` | • Allows spaces, dots, or hyphens between digits • 7–15 digits (ITU standard range) • Optional “+” |
| International Format (E.164-aligned) | `^\+?\d{7,15}$` | • Doesn’t allow spaces or special characters • Accepts 7 to 15 digits • Optional “+” |

#### Alphanumeric identifiers

| Use case | Regex pattern | Description |
| - | - | - |
| Alphanumeric Only | `^[A-Za-z0-9]+$` | Letters and digits only, any length |
| Alphanumeric with underscores | `^[A-Za-z0-9_]+$` | Letters, digits, and underscores |
| Alphanumeric with hyphens | `^[A-Za-z0-9-]+$` | Letters, digits, and hyphens (common for contract IDs, tracking numbers) |
| Alphanumeric with underscores and hyphens | `^[A-Za-z0-9_-]+$` | Letters, digits, underscores, and hyphens |
| Prefix + digits (e.g. ABC-12345) | `^[A-Za-z]{2,5}-\d{3,10}$` | Common for invoice or document numbers |

#### Other common patterns

| Use case | Regex pattern | Description |
| - | - | - |
| Street Address | ^\[0-9A-Za-z\s.,'-]+\$ | Allows numbers, letters, hyphens, and punctuation |
| Uppercase Letters Only | ^\[A-Z]+\$ | Accepts only uppercase letters |
| Lowercase Letters Only | ^\[a-z]+\$ | Accepts only lowercase letters |

## Known limitations

* Text input validation is not available for CFR Part 11 signature requests or templates.