All Features — Fillin Forge Features

Smart Conditional Logic for Dynamic Forms

Conditional logic turns a static form into a dynamic one that adapts to the user’s answers. Show a follow-up question only when it’s relevant. Hide fields that don’t apply. Make fields required only in specific scenarios. Fillin Forge’s conditional logic works on every input field type and in every form mode.

How conditional logic works in Fillin Forge

Every field in Fillin Forge has a Conditional Logic section in its settings panel. Turn it on and you can define one or more conditions that control when the field is shown or hidden.

The anatomy of a condition

A condition has three parts:

A source field — the field whose value triggers the condition
An operator — how to compare the source field’s value
A target value — what to compare against

Example: “Show this field if Inquiry Type equals Technical Support.”

Operators

Equalsexact match
Does not equalanything but the target value
Containssubstring match (text fields)
Does not containinverse of contains
Is emptyno value provided
Is not emptyany value provided
Greater thannumeric comparison
Less thannumeric comparison

Combining conditions (AND / OR)

You can add multiple conditions per field and combine them with AND or OR logic:

AND — the field shows only if ALL conditions are true
OR — the field shows if ANY condition is true

Example: “Show this field if Country equals United States AND State equals California.”

Conditional required

Conditional logic doesn’t just control visibility. A field can be set as required only when it’s visible. If a condition hides a field, it’s automatically not required — no “please fill in this required field” error for something the user can’t see. Hidden fields are also not saved with the submission.

Real-world examples

Quote form with service-specific questions

“What service are you interested in?” (dropdown: Web Design, SEO, Content, Consulting)

– If Web Design → show “Do you have an existing website?” (radio)

– If SEO → show “What’s your current monthly traffic?” (number)

– If Content → show “How many articles per month?” (number)

– If Consulting → show “What’s your business stage?” (dropdown)

“Estimated budget?” (radio, shown for all)

Healthcare intake with medical follow-ups

“Do you have any existing medical conditions?” (radio: Yes / No)

– If Yes → show “Please list them” (textarea, required)

“Are you taking any medications?” (radio: Yes / No)

– If Yes → show “Please list them” (textarea, required)

“Have you had surgery in the past 12 months?” (radio: Yes / No)

– If Yes → show “Describe the surgery” (textarea, required)

Event registration with ticket-based fields

“Ticket type?” (radio: General, VIP, Student)

– If VIP → show “Do you want airport pickup?” (checkbox)

– If Student → show “Student ID upload” (file, required)

Job application with experience-based branching

“Years of experience?” (dropdown: 0–2, 3–5, 6–10, 10+)

– If 6–10 or 10+ → show “Link to portfolio or past work” (URL, required)

– If 0–2 → show “Tell us why you’re interested in this role” (textarea, required)

Subscription with payment type

“How would you like to pay?” (radio: Credit Card, Invoice)

– If Credit Card → show Stripe payment field

– If Invoice → show “Company Name” (text) and “VAT Number” (text)

Works with the input fields and in every mode

Conditional logic works on the input fields of Fillin Forge: text, email, dropdown, checkbox, file upload, Stripe payment, calculation, map address and more. The only fields it cannot target are the layout fields: Heading, HTML Block, Divider and Page Break. It also works in every form display mode: standard, multi-step, and conversational.

In conversational mode, questions adapt based on previous answers, creating a branching conversation instead of a static questionnaire.

Setting up conditional logic

In the Fillin Forge builder:

Click the field you want to conditionally show or hide
Scroll to Conditional Logic in the right panel
Toggle “Enable conditional logic for this field” on
Choose Show this field or Hide this field
Add your conditions (source field, operator, value)
Combine with AND/OR if you have multiple
Save the form

The live preview in the builder respects conditional logic, so you can test it right in the editor without publishing.

Performance

Conditional logic runs in the visitor’s browser, so field visibility updates as the user types or selects, with no extra server requests. When the form is submitted, the server checks the rules again and ignores hidden fields, so a hidden field cannot block a submission.

Ready to build a dynamic form?

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Conditional logic is included in every paid plan and the free version.