Field Types & Validation

Every field has a type. The type decides which properties and validations the field accepts. This page is the complete reference.

Common properties

These apply to input fields regardless of type:

Property	Type	Description
`type`	enum	The field type (see below). Defaults to `TEXT`.
`label`	string	The field's display label.
`name`	string	A stable identifier for the field. Auto-generated from the type, label, and position if omitted. Needed to reference the field in conditions and merge fields. Must be unique within the form.
`required`	boolean	Whether an answer is required. Defaults to `false`. Combined with a `condition`, it means "required when visible".
`mapTo`	string	Maps the answer to a signer. See Signers.
`condition`	object	Visibility rule. See Conditional Fields & Sections.
`multipleEntries`	object	Makes the field repeatable — `{ "max": N }`. Not supported by `HTML` or `FILE`.
`prefilled`	object	A static default value set in the form. See Static prefill.

Field types

Type	Writable	Type-specific properties	Validations
`TEXT`	yes	`multiline`	`minLength`, `maxLength`, `exact`, `digitsOnly`
`NUMBER`	yes	—	`allowDecimals`, `min`, `max`, `minLength`, `maxLength`
`DATE`	yes	`dateFormat`	`minDate`, `maxDate`
`DATETIME`	yes	`datetimeFormat`	`minDate`, `maxDate`
`EMAIL`	yes	—	`minLength`, `maxLength`
`PHONE`	yes	`countryCodes`	`minLength`, `maxLength`
`NIN`	yes	`countryCodes`	—
`BUSINESS_ID`	yes	`countryCodes`	—
`CHOICE`	yes	`layout`, `options`	`min`, `max` (number of selections)
`FILE`	yes	`description`	`min`, `max` (number of files)
`HTML`	no	`content`	—

HTML is a display-only field: it renders content but collects no answer, so it can't be required, mapped, prefilled, or used as a condition target.

Validations

Pass validations under a validations object on the field:

Validation	Applies to	Description
`minLength`	TEXT, NUMBER, EMAIL, PHONE	Minimum string length. For `NUMBER`, counts the total string including any decimal point or minus sign.
`maxLength`	TEXT, NUMBER, EMAIL, PHONE	Maximum string length.
`exact`	TEXT	The value must equal this exact string.
`digitsOnly`	TEXT	The value may contain digits only.
`allowDecimals`	NUMBER	Whether decimal values are allowed.
`min` / `max`	NUMBER	Numeric bounds.
`min` / `max`	CHOICE	Minimum / maximum number of options the respondent must select.
`min` / `max`	FILE	Minimum / maximum number of files.
`minDate` / `maxDate`	DATE, DATETIME	Earliest / latest accepted date.

{
  "type": "NUMBER",
  "label": "Bank Account Number",
  "required": true,
  "validations": { "minLength": 10, "maxLength": 10, "allowDecimals": false }
}

Text and numbers

multiline turns a TEXT field into a textarea for longer answers:

{ "type": "TEXT", "label": "Additional Comments", "required": false, "multiline": true }

Dates

dateFormat (and datetimeFormat for DATETIME) controls how the value is rendered in the signed PDF, using Java date patterns. Defaults to dd/MM/yyyy.

Use uppercase MM for months. Lowercase mm means minutes and gives the wrong output.

{ "type": "DATE", "label": "Date of Birth", "required": true, "dateFormat": "dd/MM/yyyy" }

National and business IDs

NIN (national ID) and BUSINESS_ID validate the format for the countries you list in countryCodes:

{ "type": "NIN",         "label": "National ID",   "required": true, "countryCodes": ["DK", "NO", "SE"] },
{ "type": "BUSINESS_ID", "label": "Business Number","required": true, "countryCodes": ["DK", "NO", "SE", "BE"] }

Phone

PHONE validates format and lets the respondent pick a country code:

{ "type": "PHONE", "label": "Phone Number", "required": true, "countryCodes": ["DK", "NO", "SE", "DE", "GB"] }

Choices

CHOICE presents options in one of three layouts:

`layout`	Renders as	Typical use
`SELECT`	Dropdown	Many options, single selection
`RADIO`	Radio buttons	Few options, single selection
`CHECKBOX`	Checkboxes	Multiple selections

Each option has a label (shown) and a value (submitted). Set selected: true on an option to pre-select it.

{
  "type": "CHOICE",
  "label": "Employment Type",
  "required": true,
  "layout": "RADIO",
  "options": [
    { "label": "Full-time", "value": "fulltime" },
    { "label": "Part-time", "value": "parttime" },
    { "label": "Contract",  "value": "contract" }
  ]
}

Files

FILE lets the respondent upload one or more files. Bound the count with min / max:

{ "type": "FILE", "label": "Supporting Documents", "required": true, "validations": { "min": 1, "max": 3 } }

HTML content

HTML fields display formatted instructions. Only the following tags are allowed:

<p>
<em>
<strong>
<ul>
<ol>
<li>
<br>
<a[href]>

{
  "type": "HTML",
  "content": "<p><strong>Welcome!</strong></p><ul><li>Ensure all information is accurate</li><li>You'll receive a copy via email</li></ul>"
}

HTML content can embed merge fields to reflect earlier answers back to the respondent.

Static prefill

The prefilled property sets a default value in the form itself, so every respondent starts from that value. This is different from a prefilled request, which sets values per link.

{
  "type": "CHOICE",
  "label": "Country",
  "layout": "SELECT",
  "options": [
    { "label": "Denmark", "value": "DK" },
    { "label": "Sweden",  "value": "SE" }
  ],
  "prefilled": { "value": ["DK"], "editable": true }
}

Property	Type	Description
`value`	any	The default value. Its shape must match the field type (the same shapes as a prefilled request; see Field value formats).
`editable`	boolean	Whether the respondent can change it. Defaults to `false` (locked).

Only writable field types support prefilled; the value cannot be blank and must be valid for the field.