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What URL prefilling does

You can pass field values as query parameters in your form URL. When the form loads, those values are automatically filled into the corresponding fields. Respondents can still change the values unless the fields are set to read-only. This is useful for:
  • Personalizing forms sent to known contacts (pre-fill their name and email)
  • Tracking which campaign or source a respondent came from
  • Pre-selecting a product, plan, or option based on where the respondent came from
  • Passing internal IDs from your system into the form

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URL format

Add query parameters to your form URL using the prefill_ prefix followed by the field name: 
https://app.filla.io/forms/{formId}?prefill_Name=Jane+Smith&prefill_Email=jane@example.com
Filla reads the prefill_* parameters from the URL, strips the prefill_ prefix, and resolves field names to Airtable field IDs on the server. The matched fields are pre-populated when the form loads.

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Pre-fill tab in the Share view

The Pre-fill tab in the Share view (accessible from the Share tab in the form editor) provides a ready-to-use Airtable formula for generating per-record edit links: 
"<formUrl>/" & RECORD_ID()
This formula creates a unique URL for each record in your Airtable table. Paste it into a formula field in Airtable to generate edit links for every record. Click the Copy formula button to copy the formula to your clipboard.

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Supported field types for prefilling

Field typeNotes
Single line textValue used as-is
Multiline textValue used as-is
EmailValue used as-is
URLValue used as-is
Number / Currency / PercentPass a numeric value
Single selectPass the exact option name (case-sensitive)
DatePass in YYYY-MM-DD format
CheckboxPass true or false
Linked recordPass the Airtable record ID (starts with rec)

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Example

Pre-fill a contact form with a name and email from a CRM link: 
https://app.filla.io/forms/frmXyz?prefill_Name=Jane+Smith&prefill_Email=jane@example.com
The respondent opens the form and sees their name and email already filled in.

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Prefilling vs read-only

By default, respondents can override pre-filled values. If you want to lock a value (for example, an internal tracking ID that the respondent should not change):
  1. Set the field’s Default value to the URL parameter using a variable reference
  2. Enable Read-only on the field
Or pass the value via URL parameter and set the field to read-only. The URL value will populate the read-only field.

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Conflict with default values

If both a URL parameter and a field’s Default value setting are provided for the same field, the URL parameter takes precedence.

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Common questions

Yes. Query parameters are visible in the browser address bar. Do not pass sensitive data (passwords, private tokens) via URL parameters.
If the value doesn’t match an existing option, the field stays empty. The value must exactly match an existing option name.
Yes. Append the query parameters to the form URL when building your embed code’s src attribute.
Use standard URL encoding. Spaces can be written as + or %20. Other special characters should be percent-encoded (@ = %40, # = %23, etc.).