Forms support 13 field types. Here's what each one is for, and exactly what big checks before accepting a submission.

You pick the type in a page's editor, on the Type control beside the question's label. Each question in that panel is numbered in the order it's asked, and that number is how the rest of the builder refers to it — the branching rules and the per-field visibility conditions both name a question by its number and label.

The type is not only about validation: it decides what you can branch on. Single choice, Dropdown and the Agreement scale give a fixed list of answers to match against, Number and Rating compare with at least / at most, Date matches an exact day, the text types (Phone and Website included) can be tested for contains, and Multiple choice can't be branched on at all. Conditional logic has the full comparison table.

Text and numbers

• Short text — a single-line answer, up to 5000 characters.
• Long text — a multi-line answer, also up to 5000 characters.
• Number — must be a finite number (no Infinity, no NaN).

Email

Validated against a standard email format. big checks the shape of the address, not whether it's deliverable.

Instagram handle

Validated for format only — lowercase letters, numbers, periods, and underscores, 1–30 characters ([a-z0-9._]{1,30}). big does not verify that the handle belongs to a real, existing Instagram account — there's no public API for that lookup. Treat a submitted handle as "shaped like a handle," not "confirmed to exist."

Phone

A one-line box for a phone number. big accepts the number with or without spaces, dots, dashes and brackets, and with an optional leading + (or 00, which big stores as +). What's left must be 7 to 15 digits, and big stores it in that compact form, so +1 (555) 010-9999 is saved as +15550109999. big checks the shape only; it doesn't call or text the number, or check that it's in service.

A phone field can be the form's identity field, with one difference from email. See below.

Website

A one-line box for a web address. It must be an http:// or https:// address; a bare domain like example.com is accepted and stored as https://example.com/. Any other kind of address (mailto:, ftp:, and so on) is refused. big doesn't visit the address or check that the site exists.

Date

A date picker. The answer is stored as a calendar day in YYYY-MM-DD form, with no time and no time zone. An impossible date such as 2026-02-30 is refused rather than rolled over to the next month. If a date arrives with a time attached (from an import or the API), big keeps the date part only.

Choice fields

• Single choice — pick one option.
• Multiple choice — pick one or more options.
• Dropdown — pick one option from a dropdown list; big also validates that the submitted value is one of the configured options.

All three share the same option limits: 1–50 options, each up to 200 characters.

Other answers

Single choice and Multiple choice can also take an Other answer: tick Allow an Other answer on the question. Visitors then see an Other choice with a text box, and whatever they type, up to 500 characters, is saved as their answer. On Multiple choice it's saved next to the options they ticked. Dropdown has no Other answer.

An Other answer that spells one of the options, ignoring capitals and spaces, is saved as that option. Any other Other answer matches no option, so a fork such as equals Strength doesn't fire on it, and doesn't equal Strength does.

Rating

An integer rating scale. Both ends are configurable per field: the minimum can be from 0 to 9 (default 1) and the maximum up to 10, with the minimum always lower than the maximum. A 0 to 10 scale is how you ask a "how likely are you to recommend us" (NPS) question. You can also flip the scale so the highest value renders first.

A rating can also carry up to three optional scale labels, shown under the numbers: Low end, Middle and High end (for example Not likely, Neutral, Very likely), each up to 200 characters. Leave them blank and the scale shows numbers only. When you flip the scale, the low and high labels stay with their numbers, so they swap sides with them.

Agreement scale

A fixed 5-point agree/disagree scale (for example, Strongly disagree → Strongly agree). Unlike Rating, the points are fixed at five and stored by their label. You can flip the rendered order (strongly-agree first) without changing what's stored. (This type is called likert in the API and the CLI's schema output; the dashboard names it Agreement scale.)

Identity field

You can flag exactly one field on a form as the identity field — a short text, email, Instagram handle or phone field is eligible. Whatever a respondent enters there is copied to that submission's identity value, which is what big uses to recognize or de-duplicate who responded.

The identity value is the only form answer big matches against anything else (it's also what connects a response back to the short link that brought the person in). No other field is looked up or cross-referenced.

A phone identity is stored, not matched

A phone number in the identity field is saved as the response's identity. But big creates no client and no contact from it, and doesn't link the response to an existing client: Create clients from responses matches by email only. The new-response notification doesn't name a phone respondent either. If you want responses to become clients, make an Email field the identity instead.